[modbus] Split modbus_server from modbus_controller (#15509)

Co-authored-by: J. Nick Koston <nick+github@koston.org>

CODEOWNERS

@@ -347,6 +347,7 @@ esphome/components/modbus_controller/select/* @martgras @stegm
 esphome/components/modbus_controller/sensor/* @martgras
 esphome/components/modbus_controller/switch/* @martgras
 esphome/components/modbus_controller/text_sensor/* @martgras
+esphome/components/modbus_server/* @exciton
 esphome/components/mopeka_ble/* @Fabian-Schmidt @spbrogan
 esphome/components/mopeka_pro_check/* @spbrogan
 esphome/components/mopeka_std_check/* @Fabian-Schmidt

esphome/components/modbus_controller/__init__.py

@@ -3,11 +3,8 @@ import binascii
 from esphome import automation
 import esphome.codegen as cg
 from esphome.components import modbus
-from esphome.components.const import CONF_ENABLED
 from esphome.components.modbus.helpers import (
-    CPP_TYPE_REGISTER_MAP,
     MODBUS_REGISTER_TYPE,
-    SENSOR_VALUE_TYPE,
     TYPE_REGISTER_MAP,
     ModbusRegisterType,
 )
@@ -29,11 +26,10 @@ from .const import (
     CONF_ON_OFFLINE,
     CONF_ON_ONLINE,
     CONF_REGISTER_COUNT,
-    CONF_REGISTER_LAST_ADDRESS,
     CONF_REGISTER_TYPE,
-    CONF_REGISTER_VALUE,
     CONF_RESPONSE_SIZE,
     CONF_SERVER_COURTESY_RESPONSE,
+    CONF_SERVER_REGISTERS,
     CONF_SKIP_UPDATES,
     CONF_VALUE_TYPE,
 )
@@ -42,9 +38,6 @@ CODEOWNERS = ["@martgras"]
 
 AUTO_LOAD = ["modbus"]
 
-CONF_READ_LAMBDA = "read_lambda"
-CONF_WRITE_LAMBDA = "write_lambda"
-CONF_SERVER_REGISTERS = "server_registers"
 MULTI_CONF = True
 
 modbus_controller_ns = cg.esphome_ns.namespace("modbus_controller")
@@ -53,30 +46,9 @@ ModbusController = modbus_controller_ns.class_(
 )
 
 SensorItem = modbus_controller_ns.struct("SensorItem")
-ServerCourtesyResponse = modbus_controller_ns.struct("ServerCourtesyResponse")
-ServerRegister = modbus_controller_ns.struct("ServerRegister")
 
 _LOGGER = logging.getLogger(__name__)
 
-SERVER_COURTESY_RESPONSE_SCHEMA = cv.Schema(
-    {
-        cv.Optional(CONF_ENABLED, default=False): cv.boolean,
-        cv.Optional(CONF_REGISTER_LAST_ADDRESS, default=0xFFFF): cv.hex_uint16_t,
-        cv.Optional(CONF_REGISTER_VALUE, default=0): cv.hex_uint16_t,
-    }
-)
-
-ModbusServerRegisterSchema = cv.Schema(
-    {
-        cv.GenerateID(): cv.declare_id(ServerRegister),
-        cv.Required(CONF_ADDRESS): cv.positive_int,
-        cv.Optional(CONF_VALUE_TYPE, default="U_WORD"): cv.enum(SENSOR_VALUE_TYPE),
-        cv.Required(CONF_READ_LAMBDA): cv.returning_lambda,
-        cv.Optional(CONF_WRITE_LAMBDA): cv.returning_lambda,
-    }
-)
-
-
 CONFIG_SCHEMA = cv.All(
     cv.Schema(
         {
@@ -85,12 +57,16 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(
                 CONF_COMMAND_THROTTLE, default="0ms"
             ): cv.positive_time_period_milliseconds,
-            cv.Optional(CONF_SERVER_COURTESY_RESPONSE): SERVER_COURTESY_RESPONSE_SCHEMA,
+            cv.Optional(CONF_SERVER_COURTESY_RESPONSE): cv.invalid(
+                "This option has been removed. Use modbus_server component instead: https://esphome.io/components/modbus_server/"
+            ),
             cv.Optional(CONF_MAX_CMD_RETRIES, default=4): cv.positive_int,
             cv.Optional(CONF_OFFLINE_SKIP_UPDATES, default=0): cv.positive_int,
             cv.Optional(
                 CONF_SERVER_REGISTERS,
-            ): cv.ensure_list(ModbusServerRegisterSchema),
+            ): cv.invalid(
+                "This option has been removed. Use modbus_server component instead: https://esphome.io/components/modbus_server/"
+            ),
             cv.Optional(CONF_ON_COMMAND_SENT): automation.validate_automation({}),
             cv.Optional(CONF_ON_ONLINE): automation.validate_automation({}),
             cv.Optional(CONF_ON_OFFLINE): automation.validate_automation({}),
@@ -142,11 +118,9 @@ def validate_modbus_register(config):
 
 
 def _final_validate(config):
-    if CONF_SERVER_COURTESY_RESPONSE in config or CONF_SERVER_REGISTERS in config:
+    return modbus.final_validate_modbus_device("modbus_controller", role="client")(
-        return modbus.final_validate_modbus_device("modbus_controller", role="server")(
+        config
-            config
+    )
-        )
-    return config
 
 
 FINAL_VALIDATE_SCHEMA = _final_validate
@@ -228,53 +202,8 @@ async def to_code(config):
     var = cg.new_Pvariable(config[CONF_ID])
     cg.add(var.set_allow_duplicate_commands(config[CONF_ALLOW_DUPLICATE_COMMANDS]))
     cg.add(var.set_command_throttle(config[CONF_COMMAND_THROTTLE]))
-    if server_courtesy_response := config.get(CONF_SERVER_COURTESY_RESPONSE):
-        cg.add(
-            var.set_server_courtesy_response(
-                cg.StructInitializer(
-                    ServerCourtesyResponse,
-                    ("enabled", server_courtesy_response[CONF_ENABLED]),
-                    (
-                        "register_last_address",
-                        server_courtesy_response[CONF_REGISTER_LAST_ADDRESS],
-                    ),
-                    ("register_value", server_courtesy_response[CONF_REGISTER_VALUE]),
-                )
-            )
-        )
     cg.add(var.set_max_cmd_retries(config[CONF_MAX_CMD_RETRIES]))
     cg.add(var.set_offline_skip_updates(config[CONF_OFFLINE_SKIP_UPDATES]))
-    if CONF_SERVER_REGISTERS in config:
-        for server_register in config[CONF_SERVER_REGISTERS]:
-            server_register_var = cg.new_Pvariable(
-                server_register[CONF_ID],
-                server_register[CONF_ADDRESS],
-                server_register[CONF_VALUE_TYPE],
-                TYPE_REGISTER_MAP[server_register[CONF_VALUE_TYPE]],
-            )
-            cpp_type = CPP_TYPE_REGISTER_MAP[server_register[CONF_VALUE_TYPE]]
-            cg.add(
-                server_register_var.set_read_lambda(
-                    cg.TemplateArguments(cpp_type),
-                    await cg.process_lambda(
-                        server_register[CONF_READ_LAMBDA],
-                        [(cg.uint16, "address")],
-                        return_type=cpp_type,
-                    ),
-                )
-            )
-            if CONF_WRITE_LAMBDA in server_register:
-                cg.add(
-                    server_register_var.set_write_lambda(
-                        cg.TemplateArguments(cpp_type),
-                        await cg.process_lambda(
-                            server_register[CONF_WRITE_LAMBDA],
-                            parameters=[(cg.uint16, "address"), (cpp_type, "x")],
-                            return_type=cg.bool_,
-                        ),
-                    )
-                )
-            cg.add(var.add_server_register(server_register_var))
     await register_modbus_device(var, config)
     await automation.build_callback_automations(var, config, _CALLBACK_AUTOMATIONS)
 

esphome/components/modbus_controller/const.py

@@ -18,6 +18,7 @@ CONF_REGISTER_TYPE = "register_type"
 CONF_REGISTER_VALUE = "register_value"
 CONF_RESPONSE_SIZE = "response_size"
 CONF_SERVER_COURTESY_RESPONSE = "server_courtesy_response"
+CONF_SERVER_REGISTERS = "server_registers"
 CONF_SKIP_UPDATES = "skip_updates"
 CONF_USE_WRITE_MULTIPLE = "use_write_multiple"
 CONF_VALUE_TYPE = "value_type"

esphome/components/modbus_controller/modbus_controller.cpp

@@ -112,167 +112,6 @@ void ModbusController::on_modbus_error(uint8_t function_code, uint8_t exception_
   }
 }
 
-void ModbusController::on_modbus_read_registers(uint8_t function_code, uint16_t start_address,
-                                                uint16_t number_of_registers) {
-  ESP_LOGD(TAG,
-           "Received read holding/input registers for device 0x%X. FC: 0x%X. Start address: 0x%X. Number of registers: "
-           "0x%X.",
-           this->address_, function_code, start_address, number_of_registers);
-
-  if (number_of_registers == 0 || number_of_registers > modbus::MAX_NUM_OF_REGISTERS_TO_READ) {
-    ESP_LOGW(TAG, "Invalid number of registers %d. Sending exception response.", number_of_registers);
-    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_ADDRESS);
-    return;
-  }
-
-  std::vector<uint16_t> sixteen_bit_response;
-  for (uint16_t current_address = start_address; current_address < start_address + number_of_registers;) {
-    bool found = false;
-    for (auto *server_register : this->server_registers_) {
-      if (server_register->address == current_address) {
-        if (!server_register->read_lambda) {
-          break;
-        }
-        int64_t value = server_register->read_lambda();
-        ESP_LOGD(TAG, "Matched register. Address: 0x%02X. Value type: %zu. Register count: %u. Value: %s.",
-                 server_register->address, static_cast<size_t>(server_register->value_type),
-                 server_register->register_count, server_register->format_value(value).c_str());
-
-        std::vector<uint16_t> payload;
-        payload.reserve(server_register->register_count * 2);
-        modbus::helpers::number_to_payload(payload, value, server_register->value_type);
-        sixteen_bit_response.insert(sixteen_bit_response.end(), payload.cbegin(), payload.cend());
-        current_address += server_register->register_count;
-        found = true;
-        break;
-      }
-    }
-
-    if (!found) {
-      if (this->server_courtesy_response_.enabled &&
-          (current_address <= this->server_courtesy_response_.register_last_address)) {
-        ESP_LOGD(TAG,
-                 "Could not match any register to address 0x%02X, but default allowed. "
-                 "Returning default value: %d.",
-                 current_address, this->server_courtesy_response_.register_value);
-        sixteen_bit_response.push_back(this->server_courtesy_response_.register_value);
-        current_address += 1;  // Just increment by 1, as the default response is a single register
-      } else {
-        ESP_LOGW(TAG,
-                 "Could not match any register to address 0x%02X and default not allowed. Sending exception response.",
-                 current_address);
-        this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_ADDRESS);
-        return;
-      }
-    }
-  }
-
-  std::vector<uint8_t> response;
-  for (auto v : sixteen_bit_response) {
-    auto decoded_value = decode_value(v);
-    response.push_back(decoded_value[0]);
-    response.push_back(decoded_value[1]);
-  }
-
-  this->send(function_code, start_address, number_of_registers, response.size(), response.data());
-}
-
-void ModbusController::on_modbus_write_registers(uint8_t function_code, const std::vector<uint8_t> &data) {
-  uint16_t number_of_registers;
-  uint16_t payload_offset;
-
-  if (function_code == ModbusFunctionCode::WRITE_MULTIPLE_REGISTERS) {
-    if (data.size() < 5) {
-      ESP_LOGW(TAG, "Write multiple registers data too short (%zu bytes)", data.size());
-      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
-      return;
-    }
-    number_of_registers = uint16_t(data[3]) | (uint16_t(data[2]) << 8);
-    if (number_of_registers == 0 || number_of_registers > modbus::MAX_NUM_OF_REGISTERS_TO_WRITE) {
-      ESP_LOGW(TAG, "Invalid number of registers %d. Sending exception response.", number_of_registers);
-      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
-      return;
-    }
-    uint16_t payload_size = data[4];
-    if (payload_size != number_of_registers * 2) {
-      ESP_LOGW(TAG, "Payload size of %d bytes is not 2 times the number of registers (%d). Sending exception response.",
-               payload_size, number_of_registers);
-      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
-      return;
-    }
-    if (data.size() < 5 + payload_size) {
-      ESP_LOGW(TAG, "Write multiple registers payload truncated (%zu bytes, expected %u)", data.size(),
-               5 + payload_size);
-      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
-      return;
-    }
-    payload_offset = 5;
-  } else if (function_code == ModbusFunctionCode::WRITE_SINGLE_REGISTER) {
-    if (data.size() < 4) {
-      ESP_LOGW(TAG, "Write single register data too short (%zu bytes)", data.size());
-      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
-      return;
-    }
-    number_of_registers = 1;
-    payload_offset = 2;
-  } else {
-    ESP_LOGW(TAG, "Invalid function code 0x%X. Sending exception response.", function_code);
-    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_FUNCTION);
-    return;
-  }
-
-  uint16_t start_address = uint16_t(data[1]) | (uint16_t(data[0]) << 8);
-  ESP_LOGD(TAG,
-           "Received write holding registers for device 0x%X. FC: 0x%X. Start address: 0x%X. Number of registers: "
-           "0x%X.",
-           this->address_, function_code, start_address, number_of_registers);
-
-  auto for_each_register = [this, start_address, number_of_registers, payload_offset](
-                               const std::function<bool(ServerRegister *, uint16_t offset)> &callback) -> bool {
-    uint16_t offset = payload_offset;
-    for (uint16_t current_address = start_address; current_address < start_address + number_of_registers;) {
-      bool ok = false;
-      for (auto *server_register : this->server_registers_) {
-        if (server_register->address == current_address) {
-          ok = callback(server_register, offset);
-          current_address += server_register->register_count;
-          offset += server_register->register_count * sizeof(uint16_t);
-          break;
-        }
-      }
-
-      if (!ok) {
-        return false;
-      }
-    }
-    return true;
-  };
-
-  // check all registers are writable before writing to any of them:
-  if (!for_each_register([](ServerRegister *server_register, uint16_t offset) -> bool {
-        return server_register->write_lambda != nullptr;
-      })) {
-    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_FUNCTION);
-    return;
-  }
-
-  // Actually write to the registers:
-  if (!for_each_register([&data](ServerRegister *server_register, uint16_t offset) {
-        int64_t number = modbus::helpers::payload_to_number(data, server_register->value_type, offset, 0xFFFFFFFF);
-        return server_register->write_lambda(number);
-      })) {
-    this->send_error(function_code, ModbusExceptionCode::SERVICE_DEVICE_FAILURE);
-    return;
-  }
-
-  std::vector<uint8_t> response;
-  response.reserve(6);
-  response.push_back(this->address_);
-  response.push_back(function_code);
-  response.insert(response.end(), data.begin(), data.begin() + 4);
-  this->send_raw(response);
-}
-
 SensorSet ModbusController::find_sensors_(ModbusRegisterType register_type, uint16_t start_address) const {
   auto reg_it = std::find_if(
       std::begin(this->register_ranges_), std::end(this->register_ranges_),
@@ -472,14 +311,8 @@ void ModbusController::dump_config() {
                 "ModbusController:\n"
                 "  Address: 0x%02X\n"
                 "  Max Command Retries: %d\n"
-                "  Offline Skip Updates: %d\n"
+                "  Offline Skip Updates: %d\n",
-                "  Server Courtesy Response:\n"
+                this->address_, this->max_cmd_retries_, this->offline_skip_updates_);
-                "    Enabled: %s\n"
-                "    Register Last Address: 0x%02X\n"
-                "    Register Value: %d",
-                this->address_, this->max_cmd_retries_, this->offline_skip_updates_,
-                this->server_courtesy_response_.enabled ? "true" : "false",
-                this->server_courtesy_response_.register_last_address, this->server_courtesy_response_.register_value);
 
 #if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
   ESP_LOGCONFIG(TAG, "sensormap");
@@ -493,11 +326,6 @@ void ModbusController::dump_config() {
     ESP_LOGCONFIG(TAG, "  Range type=%u start=0x%X count=%d skip_updates=%d", static_cast<uint8_t>(it.register_type),
                   it.start_address, it.register_count, it.skip_updates);
   }
-  ESP_LOGCONFIG(TAG, "server registers");
-  for (auto &r : this->server_registers_) {
-    ESP_LOGCONFIG(TAG, "  Address=0x%02X value_type=%u register_count=%u", r->address,
-                  static_cast<uint8_t>(r->value_type), r->register_count);
-  }
 #endif
 }
 

esphome/components/modbus_controller/modbus_controller.h

@@ -120,82 +120,6 @@ class SensorItem {
   bool force_new_range{false};
 };
 
-struct ServerCourtesyResponse {
-  bool enabled{false};
-  uint16_t register_last_address{0xFFFF};
-  uint16_t register_value{0};
-};
-
-class ServerRegister {
-  using ReadLambda = std::function<int64_t()>;
-  using WriteLambda = std::function<bool(int64_t value)>;
-
- public:
-  ServerRegister(uint16_t address, SensorValueType value_type, uint8_t register_count) {
-    this->address = address;
-    this->value_type = value_type;
-    this->register_count = register_count;
-  }
-
-  template<typename T> void set_read_lambda(const std::function<T(uint16_t address)> &&user_read_lambda) {
-    this->read_lambda = [this, user_read_lambda]() -> int64_t {
-      T user_value = user_read_lambda(this->address);
-      if constexpr (std::is_same_v<T, float>) {
-        return bit_cast<uint32_t>(user_value);
-      } else {
-        return static_cast<int64_t>(user_value);
-      }
-    };
-  }
-
-  template<typename T>
-  void set_write_lambda(const std::function<bool(uint16_t address, const T v)> &&user_write_lambda) {
-    this->write_lambda = [this, user_write_lambda](int64_t number) {
-      if constexpr (std::is_same_v<T, float>) {
-        float float_value = bit_cast<float>(static_cast<uint32_t>(number));
-        return user_write_lambda(this->address, float_value);
-      }
-      return user_write_lambda(this->address, static_cast<T>(number));
-    };
-  }
-
-  // Formats a raw value into a string representation based on the value type for debugging
-  std::string format_value(int64_t value) const {
-    // max 44: float with %.1f can be up to 42 chars (3.4e38 → 39 integer digits + sign + decimal + 1 digit)
-    // plus null terminator = 43, rounded to 44 for 4-byte alignment
-    char buf[44];
-    switch (this->value_type) {
-      case SensorValueType::U_WORD:
-      case SensorValueType::U_DWORD:
-      case SensorValueType::U_DWORD_R:
-      case SensorValueType::U_QWORD:
-      case SensorValueType::U_QWORD_R:
-        buf_append_printf(buf, sizeof(buf), 0, "%" PRIu64, static_cast<uint64_t>(value));
-        return buf;
-      case SensorValueType::S_WORD:
-      case SensorValueType::S_DWORD:
-      case SensorValueType::S_DWORD_R:
-      case SensorValueType::S_QWORD:
-      case SensorValueType::S_QWORD_R:
-        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
-        return buf;
-      case SensorValueType::FP32_R:
-      case SensorValueType::FP32:
-        buf_append_printf(buf, sizeof(buf), 0, "%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
-        return buf;
-      default:
-        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
-        return buf;
-    }
-  }
-
-  uint16_t address{0};
-  SensorValueType value_type{SensorValueType::RAW};
-  uint8_t register_count{0};
-  ReadLambda read_lambda;
-  WriteLambda write_lambda;
-};
-
 // ModbusController::create_register_ranges_ tries to optimize register range
 // for this the sensors must be ordered by register_type, start_address and bitmask
 class SensorItemsComparator {
@@ -367,16 +291,10 @@ class ModbusController : public PollingComponent, public modbus::ModbusDevice {
   void queue_command(const ModbusCommandItem &command);
   /// Registers a sensor with the controller. Called by esphomes code generator
   void add_sensor_item(SensorItem *item) { sensorset_.insert(item); }
-  /// Registers a server register with the controller. Called by esphomes code generator
-  void add_server_register(ServerRegister *server_register) { server_registers_.push_back(server_register); }
   /// called when a modbus response was parsed without errors
   void on_modbus_data(const std::vector<uint8_t> &data) override;
   /// called when a modbus error response was received
   void on_modbus_error(uint8_t function_code, uint8_t exception_code) override;
-  /// called when a modbus request (function code 0x03 or 0x04) was parsed without errors
-  void on_modbus_read_registers(uint8_t function_code, uint16_t start_address, uint16_t number_of_registers) final;
-  /// called when a modbus request (function code 0x06 or 0x10) was parsed without errors
-  void on_modbus_write_registers(uint8_t function_code, const std::vector<uint8_t> &data) final;
   /// default delegate called by process_modbus_data when a response has retrieved from the incoming queue
   void on_register_data(ModbusRegisterType register_type, uint16_t start_address, const std::vector<uint8_t> &data);
   /// default delegate called by process_modbus_data when a response for a write response has retrieved from the
@@ -413,12 +331,6 @@ class ModbusController : public PollingComponent, public modbus::ModbusDevice {
   void set_max_cmd_retries(uint8_t max_cmd_retries) { this->max_cmd_retries_ = max_cmd_retries; }
   /// get how many times a command will be (re)sent if no response is received
   uint8_t get_max_cmd_retries() { return this->max_cmd_retries_; }
-  /// Called by esphome generated code to set the server courtesy response object
-  void set_server_courtesy_response(const ServerCourtesyResponse &server_courtesy_response) {
-    this->server_courtesy_response_ = server_courtesy_response;
-  }
-  /// Get the server courtesy response object
-  ServerCourtesyResponse get_server_courtesy_response() const { return this->server_courtesy_response_; }
 
  protected:
   /// parse sensormap_ and create range of sequential addresses
@@ -435,8 +347,6 @@ class ModbusController : public PollingComponent, public modbus::ModbusDevice {
   void dump_sensors_();
   /// Collection of all sensors for this component
   SensorSet sensorset_;
-  /// Collection of all server registers for this component
-  std::vector<ServerRegister *> server_registers_{};
   /// Continuous range of modbus registers
   std::vector<RegisterRange> register_ranges_{};
   /// Hold the pending requests to be sent
@@ -461,9 +371,6 @@ class ModbusController : public PollingComponent, public modbus::ModbusDevice {
   CallbackManager<void(int, int)> online_callback_{};
   /// Server offline callback
   CallbackManager<void(int, int)> offline_callback_{};
-  /// Server courtesy response
-  ServerCourtesyResponse server_courtesy_response_{
-      .enabled = false, .register_last_address = 0xFFFF, .register_value = 0};
 };
 
 /** Convert vector<uint8_t> response payload to float.

esphome/components/modbus_server/__init__.py

@@ -0,0 +1,124 @@
+import esphome.codegen as cg
+from esphome.components import modbus
+from esphome.components.const import CONF_ENABLED
+from esphome.components.modbus.helpers import (
+    CPP_TYPE_REGISTER_MAP,
+    SENSOR_VALUE_TYPE,
+    TYPE_REGISTER_MAP,
+)
+import esphome.config_validation as cv
+from esphome.const import CONF_ADDRESS, CONF_ID
+
+from .const import (
+    CONF_COURTESY_RESPONSE,
+    CONF_READ_LAMBDA,
+    CONF_REGISTER_LAST_ADDRESS,
+    CONF_REGISTER_VALUE,
+    CONF_REGISTERS,
+    CONF_VALUE_TYPE,
+    CONF_WRITE_LAMBDA,
+)
+
+CODEOWNERS = ["@exciton"]
+
+AUTO_LOAD = ["modbus"]
+
+MULTI_CONF = True
+
+modbus_server_ns = cg.esphome_ns.namespace("modbus_server")
+ModbusServer = modbus_server_ns.class_(
+    "ModbusServer", cg.Component, modbus.ModbusDevice
+)
+
+ServerCourtesyResponse = modbus_server_ns.struct("ServerCourtesyResponse")
+ServerRegister = modbus_server_ns.struct("ServerRegister")
+
+SERVER_COURTESY_RESPONSE_SCHEMA = cv.Schema(
+    {
+        cv.Optional(CONF_ENABLED, default=False): cv.boolean,
+        cv.Optional(CONF_REGISTER_LAST_ADDRESS, default=0xFFFF): cv.hex_uint16_t,
+        cv.Optional(CONF_REGISTER_VALUE, default=0): cv.hex_uint16_t,
+    }
+)
+
+ModbusServerRegisterSchema = cv.Schema(
+    {
+        cv.GenerateID(): cv.declare_id(ServerRegister),
+        cv.Required(CONF_ADDRESS): cv.positive_int,
+        cv.Optional(CONF_VALUE_TYPE, default="U_WORD"): cv.enum(SENSOR_VALUE_TYPE),
+        cv.Required(CONF_READ_LAMBDA): cv.returning_lambda,
+        cv.Optional(CONF_WRITE_LAMBDA): cv.returning_lambda,
+    }
+)
+
+
+CONFIG_SCHEMA = cv.All(
+    cv.Schema(
+        {
+            cv.GenerateID(): cv.declare_id(ModbusServer),
+            cv.Optional(CONF_COURTESY_RESPONSE): SERVER_COURTESY_RESPONSE_SCHEMA,
+            cv.Optional(
+                CONF_REGISTERS,
+            ): cv.ensure_list(ModbusServerRegisterSchema),
+        }
+    ).extend(modbus.modbus_device_schema(0x01)),
+)
+
+
+def _final_validate(config):
+    return modbus.final_validate_modbus_device("modbus_server", role="server")(config)
+
+
+FINAL_VALIDATE_SCHEMA = _final_validate
+
+
+async def to_code(config):
+    var = cg.new_Pvariable(config[CONF_ID])
+    if server_courtesy_response := config.get(CONF_COURTESY_RESPONSE):
+        cg.add(
+            var.set_server_courtesy_response(
+                cg.StructInitializer(
+                    ServerCourtesyResponse,
+                    ("enabled", server_courtesy_response[CONF_ENABLED]),
+                    (
+                        "register_last_address",
+                        server_courtesy_response[CONF_REGISTER_LAST_ADDRESS],
+                    ),
+                    ("register_value", server_courtesy_response[CONF_REGISTER_VALUE]),
+                )
+            )
+        )
+    if CONF_REGISTERS in config:
+        for server_register in config[CONF_REGISTERS]:
+            server_register_var = cg.new_Pvariable(
+                server_register[CONF_ID],
+                server_register[CONF_ADDRESS],
+                server_register[CONF_VALUE_TYPE],
+                TYPE_REGISTER_MAP[server_register[CONF_VALUE_TYPE]],
+            )
+            cpp_type = CPP_TYPE_REGISTER_MAP[server_register[CONF_VALUE_TYPE]]
+            cg.add(
+                server_register_var.set_read_lambda(
+                    cg.TemplateArguments(cpp_type),
+                    await cg.process_lambda(
+                        server_register[CONF_READ_LAMBDA],
+                        [(cg.uint16, "address")],
+                        return_type=cpp_type,
+                    ),
+                )
+            )
+            if CONF_WRITE_LAMBDA in server_register:
+                cg.add(
+                    server_register_var.set_write_lambda(
+                        cg.TemplateArguments(cpp_type),
+                        await cg.process_lambda(
+                            server_register[CONF_WRITE_LAMBDA],
+                            parameters=[(cg.uint16, "address"), (cpp_type, "x")],
+                            return_type=cg.bool_,
+                        ),
+                    )
+                )
+            cg.add(var.add_server_register(server_register_var))
+    cg.add(var.set_address(config[CONF_ADDRESS]))
+    await cg.register_component(var, config)
+    return await modbus.register_modbus_device(var, config)

esphome/components/modbus_server/const.py

@@ -0,0 +1,7 @@
+CONF_REGISTER_LAST_ADDRESS = "register_last_address"
+CONF_REGISTER_VALUE = "register_value"
+CONF_VALUE_TYPE = "value_type"
+CONF_COURTESY_RESPONSE = "courtesy_response"
+CONF_READ_LAMBDA = "read_lambda"
+CONF_WRITE_LAMBDA = "write_lambda"
+CONF_REGISTERS = "registers"

esphome/components/modbus_server/modbus_server.cpp

@@ -0,0 +1,192 @@
+#include "modbus_server.h"
+#include "esphome/core/application.h"
+#include "esphome/core/log.h"
+
+namespace esphome::modbus_server {
+using modbus::ModbusFunctionCode;
+using modbus::ModbusExceptionCode;
+
+static const char *const TAG = "modbus_server";
+
+void ModbusServer::on_modbus_read_registers(uint8_t function_code, uint16_t start_address,
+                                            uint16_t number_of_registers) {
+  ESP_LOGD(TAG,
+           "Received read holding/input registers for device 0x%X. FC: 0x%X. Start address: 0x%X. Number of registers: "
+           "0x%X.",
+           this->address_, function_code, start_address, number_of_registers);
+
+  if (number_of_registers == 0 || number_of_registers > modbus::MAX_NUM_OF_REGISTERS_TO_READ) {
+    ESP_LOGW(TAG, "Invalid number of registers %d. Sending exception response.", number_of_registers);
+    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_ADDRESS);
+    return;
+  }
+
+  std::vector<uint16_t> sixteen_bit_response;
+  for (uint16_t current_address = start_address; current_address < start_address + number_of_registers;) {
+    bool found = false;
+    for (auto *server_register : this->server_registers_) {
+      if (server_register->address == current_address) {
+        if (!server_register->read_lambda) {
+          break;
+        }
+        int64_t value = server_register->read_lambda();
+        ESP_LOGD(TAG, "Matched register. Address: 0x%02X. Value type: %zu. Register count: %u. Value: %s.",
+                 server_register->address, static_cast<size_t>(server_register->value_type),
+                 server_register->register_count, server_register->format_value(value).c_str());
+
+        std::vector<uint16_t> payload;
+        payload.reserve(server_register->register_count * 2);
+        modbus::helpers::number_to_payload(payload, value, server_register->value_type);
+        sixteen_bit_response.insert(sixteen_bit_response.end(), payload.cbegin(), payload.cend());
+        current_address += server_register->register_count;
+        found = true;
+        break;
+      }
+    }
+
+    if (!found) {
+      if (this->server_courtesy_response_.enabled &&
+          (current_address <= this->server_courtesy_response_.register_last_address)) {
+        ESP_LOGD(TAG,
+                 "Could not match any register to address 0x%02X, but default allowed. "
+                 "Returning default value: %d.",
+                 current_address, this->server_courtesy_response_.register_value);
+        sixteen_bit_response.push_back(this->server_courtesy_response_.register_value);
+        current_address += 1;  // Just increment by 1, as the default response is a single register
+      } else {
+        ESP_LOGW(TAG,
+                 "Could not match any register to address 0x%02X and default not allowed. Sending exception response.",
+                 current_address);
+        this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_ADDRESS);
+        return;
+      }
+    }
+  }
+
+  std::vector<uint8_t> response;
+  for (auto v : sixteen_bit_response) {
+    auto decoded_value = decode_value(v);
+    response.push_back(decoded_value[0]);
+    response.push_back(decoded_value[1]);
+  }
+
+  this->send(function_code, start_address, number_of_registers, response.size(), response.data());
+}
+
+void ModbusServer::on_modbus_write_registers(uint8_t function_code, const std::vector<uint8_t> &data) {
+  uint16_t number_of_registers;
+  uint16_t payload_offset;
+
+  if (function_code == ModbusFunctionCode::WRITE_MULTIPLE_REGISTERS) {
+    if (data.size() < 5) {
+      ESP_LOGW(TAG, "Write multiple registers data too short (%zu bytes)", data.size());
+      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
+      return;
+    }
+    number_of_registers = uint16_t(data[3]) | (uint16_t(data[2]) << 8);
+    if (number_of_registers == 0 || number_of_registers > modbus::MAX_NUM_OF_REGISTERS_TO_WRITE) {
+      ESP_LOGW(TAG, "Invalid number of registers %d. Sending exception response.", number_of_registers);
+      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
+      return;
+    }
+    uint16_t payload_size = data[4];
+    if (payload_size != number_of_registers * 2) {
+      ESP_LOGW(TAG, "Payload size of %d bytes is not 2 times the number of registers (%d). Sending exception response.",
+               payload_size, number_of_registers);
+      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
+      return;
+    }
+    if (data.size() < 5 + payload_size) {
+      ESP_LOGW(TAG, "Write multiple registers payload truncated (%zu bytes, expected %u)", data.size(),
+               5 + payload_size);
+      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
+      return;
+    }
+    payload_offset = 5;
+  } else if (function_code == ModbusFunctionCode::WRITE_SINGLE_REGISTER) {
+    if (data.size() < 4) {
+      ESP_LOGW(TAG, "Write single register data too short (%zu bytes)", data.size());
+      this->send_error(function_code, ModbusExceptionCode::ILLEGAL_DATA_VALUE);
+      return;
+    }
+    number_of_registers = 1;
+    payload_offset = 2;
+  } else {
+    ESP_LOGW(TAG, "Invalid function code 0x%X. Sending exception response.", function_code);
+    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_FUNCTION);
+    return;
+  }
+
+  uint16_t start_address = uint16_t(data[1]) | (uint16_t(data[0]) << 8);
+  ESP_LOGD(TAG,
+           "Received write holding registers for device 0x%X. FC: 0x%X. Start address: 0x%X. Number of registers: "
+           "0x%X.",
+           this->address_, function_code, start_address, number_of_registers);
+
+  auto for_each_register = [this, start_address, number_of_registers, payload_offset](
+                               const std::function<bool(ServerRegister *, uint16_t offset)> &callback) -> bool {
+    uint16_t offset = payload_offset;
+    for (uint16_t current_address = start_address; current_address < start_address + number_of_registers;) {
+      bool ok = false;
+      for (auto *server_register : this->server_registers_) {
+        if (server_register->address == current_address) {
+          ok = callback(server_register, offset);
+          current_address += server_register->register_count;
+          offset += server_register->register_count * sizeof(uint16_t);
+          break;
+        }
+      }
+
+      if (!ok) {
+        return false;
+      }
+    }
+    return true;
+  };
+
+  // check all registers are writable before writing to any of them:
+  if (!for_each_register([](ServerRegister *server_register, uint16_t offset) -> bool {
+        return server_register->write_lambda != nullptr;
+      })) {
+    this->send_error(function_code, ModbusExceptionCode::ILLEGAL_FUNCTION);
+    return;
+  }
+
+  // Actually write to the registers:
+  if (!for_each_register([&data](ServerRegister *server_register, uint16_t offset) {
+        int64_t number = modbus::helpers::payload_to_number(data, server_register->value_type, offset, 0xFFFFFFFF);
+        return server_register->write_lambda(number);
+      })) {
+    this->send_error(function_code, ModbusExceptionCode::SERVICE_DEVICE_FAILURE);
+    return;
+  }
+
+  std::vector<uint8_t> response;
+  response.reserve(6);
+  response.push_back(this->address_);
+  response.push_back(function_code);
+  response.insert(response.end(), data.begin(), data.begin() + 4);
+  this->send_raw(response);
+}
+
+void ModbusServer::dump_config() {
+  ESP_LOGCONFIG(TAG,
+                "ModbusServer:\n"
+                "  Address: 0x%02X\n"
+                "  Server Courtesy Response:\n"
+                "    Enabled: %s\n"
+                "    Register Last Address: 0x%02X\n"
+                "    Register Value: %" PRIu16,
+                this->address_, this->server_courtesy_response_.enabled ? "true" : "false",
+                this->server_courtesy_response_.register_last_address, this->server_courtesy_response_.register_value);
+
+#if ESPHOME_LOG_LEVEL >= ESPHOME_LOG_LEVEL_VERBOSE
+  ESP_LOGCONFIG(TAG, "server registers");
+  for (auto &r : this->server_registers_) {
+    ESP_LOGCONFIG(TAG, "  Address=0x%02X value_type=%u register_count=%u", r->address,
+                  static_cast<uint8_t>(r->value_type), r->register_count);
+  }
+#endif
+}
+
+}  // namespace esphome::modbus_server

esphome/components/modbus_server/modbus_server.h

@@ -0,0 +1,119 @@
+#pragma once
+
+#include "esphome/core/component.h"
+
+#include "esphome/components/modbus/modbus.h"
+#include "esphome/components/modbus/modbus_helpers.h"
+#include "esphome/core/automation.h"
+
+#include <utility>
+#include <vector>
+
+namespace esphome::modbus_server {
+
+using modbus::helpers::SensorValueType;
+
+struct ServerCourtesyResponse {
+  bool enabled{false};
+  uint16_t register_last_address{0xFFFF};
+  uint16_t register_value{0};
+};
+
+class ServerRegister {
+  using ReadLambda = std::function<int64_t()>;
+  using WriteLambda = std::function<bool(int64_t value)>;
+
+ public:
+  ServerRegister(uint16_t address, SensorValueType value_type, uint8_t register_count) {
+    this->address = address;
+    this->value_type = value_type;
+    this->register_count = register_count;
+  }
+
+  template<typename T> void set_read_lambda(const std::function<T(uint16_t address)> &&user_read_lambda) {
+    this->read_lambda = [this, user_read_lambda]() -> int64_t {
+      T user_value = user_read_lambda(this->address);
+      if constexpr (std::is_same_v<T, float>) {
+        return bit_cast<uint32_t>(user_value);
+      } else {
+        return static_cast<int64_t>(user_value);
+      }
+    };
+  }
+
+  template<typename T>
+  void set_write_lambda(const std::function<bool(uint16_t address, const T v)> &&user_write_lambda) {
+    this->write_lambda = [this, user_write_lambda](int64_t number) {
+      if constexpr (std::is_same_v<T, float>) {
+        float float_value = bit_cast<float>(static_cast<uint32_t>(number));
+        return user_write_lambda(this->address, float_value);
+      }
+      return user_write_lambda(this->address, static_cast<T>(number));
+    };
+  }
+
+  // Formats a raw value into a string representation based on the value type for debugging
+  std::string format_value(int64_t value) const {
+    // max 44: float with %.1f can be up to 42 chars (3.4e38 → 39 integer digits + sign + decimal + 1 digit)
+    // plus null terminator = 43, rounded to 44 for 4-byte alignment
+    char buf[44];
+    switch (this->value_type) {
+      case SensorValueType::U_WORD:
+      case SensorValueType::U_DWORD:
+      case SensorValueType::U_DWORD_R:
+      case SensorValueType::U_QWORD:
+      case SensorValueType::U_QWORD_R:
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRIu64, static_cast<uint64_t>(value));
+        return buf;
+      case SensorValueType::S_WORD:
+      case SensorValueType::S_DWORD:
+      case SensorValueType::S_DWORD_R:
+      case SensorValueType::S_QWORD:
+      case SensorValueType::S_QWORD_R:
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
+      case SensorValueType::FP32_R:
+      case SensorValueType::FP32:
+        buf_append_printf(buf, sizeof(buf), 0, "%.1f", bit_cast<float>(static_cast<uint32_t>(value)));
+        return buf;
+      default:
+        buf_append_printf(buf, sizeof(buf), 0, "%" PRId64, value);
+        return buf;
+    }
+  }
+
+  uint16_t address{0};
+  SensorValueType value_type{SensorValueType::RAW};
+  uint8_t register_count{0};
+  ReadLambda read_lambda;
+  WriteLambda write_lambda;
+};
+
+class ModbusServer : public Component, public modbus::ModbusDevice {
+ public:
+  void dump_config() override;
+
+  /// Not used for ModbusServer.
+  void on_modbus_data(const std::vector<uint8_t> &data) override{};
+  /// Registers a server register with the controller. Called by esphomes code generator
+  void add_server_register(ServerRegister *server_register) { server_registers_.push_back(server_register); }
+  /// called when a modbus request (function code 0x03 or 0x04) was parsed without errors
+  void on_modbus_read_registers(uint8_t function_code, uint16_t start_address, uint16_t number_of_registers) final;
+  /// called when a modbus request (function code 0x06 or 0x10) was parsed without errors
+  void on_modbus_write_registers(uint8_t function_code, const std::vector<uint8_t> &data) final;
+  /// Called by esphome generated code to set the server courtesy response object
+  void set_server_courtesy_response(const ServerCourtesyResponse &server_courtesy_response) {
+    this->server_courtesy_response_ = server_courtesy_response;
+  }
+  /// Get the server courtesy response object
+  ServerCourtesyResponse get_server_courtesy_response() const { return this->server_courtesy_response_; }
+
+ protected:
+  /// Collection of all server registers for this component
+  std::vector<ServerRegister *> server_registers_{};
+  /// Server courtesy response
+  ServerCourtesyResponse server_courtesy_response_{
+      .enabled = false, .register_last_address = 0xFFFF, .register_value = 0};
+};
+
+}  // namespace esphome::modbus_server

tests/components/modbus_controller/common.yaml

@@ -1,53 +1,11 @@
-modbus:
-  - id: mod_bus2
-    uart_id: uart_bus
-    role: server
-
 modbus_controller:
   - id: modbus_controller1
     address: 0x2
     modbus_id: modbus_bus
-    allow_duplicate_commands: false
     on_online:
       then:
         logger.log: "Module Online"
-  - id: modbus_controller2
+
-    address: 0x2
-    modbus_id: mod_bus2
-    server_registers:
-      - address: 0x0000
-        value_type: S_DWORD_R
-        read_lambda: |-
-          return 42.3;
-    max_cmd_retries: 0
-  - id: modbus_controller3
-    address: 0x3
-    modbus_id: mod_bus2
-    server_registers:
-      - address: 0x0009
-        value_type: S_DWORD
-        read_lambda: |-
-          return 31;
-        write_lambda: |-
-          printf("address=%d, value=%d", x);
-          return true;
-    max_cmd_retries: 0
-  - id: modbus_controller4
-    modbus_id: mod_bus2
-    address: 0x4
-    server_courtesy_response:
-      enabled: true
-      register_last_address: 100
-      register_value: 0
-    server_registers:
-      - address: 0x0001
-        value_type: U_WORD
-        read_lambda: |-
-          return 0x8;
-      - address: 0x0005
-        value_type: U_WORD
-        read_lambda: |-
-          return (random_uint32() % 100);
 binary_sensor:
   - platform: modbus_controller
     modbus_controller_id: modbus_controller1

tests/components/modbus_server/common.yaml

@@ -0,0 +1,41 @@
+modbus:
+  - id: mod_bus2
+    uart_id: uart_bus
+    role: server
+
+modbus_server:
+  - id: modbus_server2
+    address: 0x2
+    modbus_id: mod_bus2
+    registers:
+      - address: 0x0
+        value_type: S_DWORD_R
+        read_lambda: |-
+          return 42.3;
+  - id: modbus_server3
+    address: 0x3
+    modbus_id: mod_bus2
+    registers:
+      - address: 0x9
+        value_type: S_DWORD
+        read_lambda: |-
+          return 31;
+        write_lambda: |-
+          printf("address=%d, value=%d", x);
+          return true;
+  - id: modbus_server4
+    modbus_id: mod_bus2
+    address: 0x4
+    courtesy_response:
+      enabled: true
+      register_last_address: 100
+      register_value: 0
+    registers:
+      - address: 0x1
+        value_type: U_WORD
+        read_lambda: |-
+          return 0x8;
+      - address: 0x5
+        value_type: U_WORD
+        read_lambda: |-
+          return (random_uint32() % 100);

tests/components/modbus_server/test.esp32-idf.yaml

@@ -0,0 +1,4 @@
+packages:
+  modbus: !include ../../test_build_components/common/modbus/esp32-idf.yaml
+
+<<: !include common.yaml

tests/components/modbus_server/test.esp8266-ard.yaml

@@ -0,0 +1,4 @@
+packages:
+  modbus: !include ../../test_build_components/common/modbus/esp8266-ard.yaml
+
+<<: !include common.yaml

tests/components/modbus_server/test.rp2040-ard.yaml

@@ -0,0 +1,4 @@
+packages:
+  modbus: !include ../../test_build_components/common/modbus/rp2040-ard.yaml
+
+<<: !include common.yaml

tests/integration/fixtures/uart_mock_modbus_server.yaml

@@ -86,9 +86,9 @@ modbus:
   uart_id: virtual_uart_dev
   role: server
 
-modbus_controller:
+modbus_server:
   - address: 1
-    server_registers:
+    registers:
       - address: 0x03
         value_type: U_WORD
         read_lambda: |-

tests/integration/fixtures/uart_mock_modbus_server_controller.yaml

@@ -33,7 +33,7 @@ uart_mock:
               data: !lambda return data;
   - id: virtual_uart_controller
     baud_rate: 9600
-    auto_start: true  # See comment on virtual_uart_server above
+    auto_start: true # See comment on virtual_uart_server above
     debug:
     on_tx:
       - then:
@@ -56,10 +56,11 @@ modbus_controller:
     update_interval: 1s
     id: modbus_controller_1
 
+modbus_server:
   - address: 1
     modbus_id: virtual_modbus_server
     id: modbus_server_1
-    server_registers:
+    registers:
       - address: 0x01
         value_type: U_WORD
         read_lambda: return 99;

tests/integration/fixtures/uart_mock_modbus_server_controller_multiple.yaml

@@ -36,7 +36,7 @@ uart_mock:
               data: !lambda return data;
   - id: virtual_uart_server_2
     baud_rate: 9600
-    auto_start: true  # See comment on virtual_uart_server above
+    auto_start: true # See comment on virtual_uart_server above
     debug:
     on_tx:
       - then:
@@ -48,7 +48,7 @@ uart_mock:
               data: !lambda return data;
   - id: virtual_uart_controller
     baud_rate: 9600
-    auto_start: true  # See comment on virtual_uart_server above
+    auto_start: true # See comment on virtual_uart_server above
     debug:
     on_tx:
       - then:
@@ -81,15 +81,16 @@ modbus_controller:
     update_interval: 1s
     id: modbus_controller_2
 
+modbus_server:
   - address: 1
     modbus_id: virtual_modbus_server
-    server_registers:
+    registers:
       - address: 0x01
         value_type: U_WORD
         read_lambda: return 919;
   - address: 2
     modbus_id: virtual_modbus_server_2
-    server_registers:
+    registers:
       - address: 0x01
         value_type: U_WORD
         read_lambda: return 929;

tests/integration/fixtures/uart_mock_modbus_server_controller_write.yaml

@@ -33,7 +33,7 @@ uart_mock:
               data: !lambda return data;
   - id: virtual_uart_controller
     baud_rate: 9600
-    auto_start: true  # See comment on virtual_uart_server above
+    auto_start: true # See comment on virtual_uart_server above
     debug:
     on_tx:
       - then:
@@ -94,10 +94,11 @@ modbus_controller:
     update_interval: 2s
     id: modbus_controller_1
 
+modbus_server:
   - address: 1
     modbus_id: virtual_modbus_server
     id: modbus_server_1
-    server_registers:
+    registers:
       - address: 0x01
         value_type: U_WORD
         read_lambda: return id(stored_u_word);