diff --git a/boards/sim/sim/sim/configs/nxmbrtu/defconfig b/boards/sim/sim/sim/configs/nxmbrtu/defconfig
new file mode 100644
index 00000000000..f6b894166b7
--- /dev/null
+++ b/boards/sim/sim/sim/configs/nxmbrtu/defconfig
@@ -0,0 +1,59 @@
+#
+# This file is autogenerated: PLEASE DO NOT EDIT IT.
+#
+# You can use "make menuconfig" to make any modifications to the installed .config file.
+# You can then do "make savedefconfig" to generate a new defconfig file that includes your
+# modifications.
+#
+# CONFIG_NSH_CMDOPT_HEXDUMP is not set
+CONFIG_ARCH="sim"
+CONFIG_ARCH_BOARD="sim"
+CONFIG_ARCH_BOARD_SIM=y
+CONFIG_ARCH_CHIP="sim"
+CONFIG_ARCH_SIM=y
+CONFIG_BOARDCTL_APP_SYMTAB=y
+CONFIG_BOARDCTL_POWEROFF=y
+CONFIG_BOARD_LOOPSPERMSEC=0
+CONFIG_BOOT_RUNFROMEXTSRAM=y
+CONFIG_BUILTIN=y
+CONFIG_DEBUG_ASSERTIONS=y
+CONFIG_DEBUG_FEATURES=y
+CONFIG_DEBUG_SYMBOLS=y
+CONFIG_DEV_LOOP=y
+CONFIG_EXAMPLES_NXMBSERVER=y
+CONFIG_FS_BINFS=y
+CONFIG_FS_PROCFS=y
+CONFIG_HAVE_CXXINITIALIZE=y
+CONFIG_IDLETHREAD_STACKSIZE=4096
+CONFIG_INIT_ENTRYPOINT="nsh_main"
+CONFIG_LIBC_ENVPATH=y
+CONFIG_LIBC_EXECFUNCS=y
+CONFIG_LIBC_MAX_EXITFUNS=1
+CONFIG_NSH_ARCHINIT=y
+CONFIG_NSH_BUILTIN_APPS=y
+CONFIG_NSH_FILE_APPS=y
+CONFIG_NSH_MAXARGUMENTS=32
+CONFIG_NSH_READLINE=y
+CONFIG_NXMODBUS=y
+CONFIG_NXMODBUS_ASCII=y
+CONFIG_NXMODBUS_CLIENT=y
+CONFIG_PATH_INITIAL="/bin"
+CONFIG_PIPES=y
+CONFIG_PSEUDOFS_ATTRIBUTES=y
+CONFIG_PSEUDOFS_FILE=y
+CONFIG_PSEUDOFS_SOFTLINKS=y
+CONFIG_READLINE_CMD_HISTORY=y
+CONFIG_READLINE_TABCOMPLETION=y
+CONFIG_SCHED_BACKTRACE=y
+CONFIG_SCHED_HAVE_PARENT=y
+CONFIG_SCHED_WAITPID=y
+CONFIG_SERIAL_TERMIOS=y
+CONFIG_SIM_UART0_NAME="/tmp/ttyNXB0"
+CONFIG_SIM_UART1_NAME="/tmp/ttyNXB1"
+CONFIG_SIM_UART_BUFFER_SIZE=1024
+CONFIG_SIM_UART_NUMBER=2
+CONFIG_SIM_WALLTIME_SIGNAL=y
+CONFIG_START_MONTH=6
+CONFIG_START_YEAR=2008
+CONFIG_SYSTEM_NSH=y
+CONFIG_SYSTEM_NXMBCLIENT=y