serial2TCP forwarding example

doc/source/example/modbus_forwarder.rst

@@ -1,4 +1,4 @@
 ==================================================
-Serial Forwarder Example
+Forwarder Example
 ==================================================
 .. literalinclude:: ../../../examples/modbus_forwarder.py

doc/source/example/modbus_serial_forwarder.rst

@@ -0,0 +1,4 @@
+==================================================
+Serial Forwarder Example
+==================================================
+.. literalinclude:: ../../../examples/serial_forwarder.py

doc/source/example/modules.rst

@@ -19,6 +19,7 @@ Examples
    dbstore_update_server
    modbus_logging
    modbus_forwarder
+   modbus_serial_forwarder
    payload_client
    payload_server
    performance

examples/serial_forwarder.py

@@ -0,0 +1,88 @@
+"""Pymodbus SerialRTU2TCP Forwarder
+
+usage :
+python3 serial_forwarder.py --log DEBUG --port "/dev/ttyUSB0" --baudrate 9600 --server_ip "192.168.1.27" --server_port 5020 --slaves 1 2 3
+
+sudo python3 serial_forwarder.py --port "/dev/ttyUSB0" --baudrate 9600 --server_ip "192.168.1.27" --server_port=502 --slaves 1 2 3
+"""
+# pylint: disable=unused-argument
+import argparse
+import logging
+import signal
+
+from pymodbus.server.async_io import ModbusTcpServer
+from pymodbus.client import ModbusSerialClient
+from pymodbus.datastore import ModbusServerContext
+from pymodbus.datastore.remote import RemoteSlaveContext
+
+FORMAT = "%(asctime)-15s %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
+logging.basicConfig(format=FORMAT)
+_logger = logging.getLogger()
+
+
+def raise_graceful_exit(*args):
+    """Enters shutdown mode"""
+    _logger.info("receiving shutdown signal now")
+    raise SystemExit
+
+
+class SerialForwarderTCPServer():
+    """SerialRTU2TCP Forwarder Server"""
+
+    def __init__(self):
+        """Initialize the server"""
+        self.server = None
+
+    async def run(self):
+        """Run the server"""
+        port, baudrate, server_port, server_ip, slaves = get_commandline()
+        client = ModbusSerialClient(method='rtu', port=port, baudrate=baudrate)
+        message = f'RTU bus on {port} - baudrate {baudrate}'
+        _logger.info(message)
+        store = {}
+        for i in slaves:
+            store[i] = RemoteSlaveContext(client, unit=i)
+        context = ModbusServerContext(slaves=store, single=False)
+        self.server = ModbusTcpServer(context, address=(server_ip, server_port), allow_reuse_address=True)
+        message = f'serving on {server_ip} port {server_port}'
+        _logger.info(message)
+        message = f'listening to slaves {context.slaves()}'
+        _logger.info(message)
+        await self.server.serve_forever()
+
+    async def stop(self):
+        """Stop the server"""
+        if self.server:
+            await self.server.shutdown()
+            _logger.info("TCP server is down")
+
+
+def get_commandline():
+    """Read and validate command line arguments"""
+    logchoices = ["critical", "error", "warning", "info", "debug"]
+
+    parser = argparse.ArgumentParser(description="Command line options for examples")
+    parser.add_argument("--log", help=",".join(logchoices), default="info", type=str)
+    parser.add_argument("--port", help="RTU serial port", default='/dev/ttyUSB0', type=str)
+    parser.add_argument("--baudrate", help="RTU baudrate", default=9600, type=int)
+    parser.add_argument("--server_port", help="server port", default=5020, type=int)
+    parser.add_argument("--server_ip", help="server IP", default="127.0.0.1", type=str)
+    parser.add_argument("--slaves", help="list of slaves to forward", type=int, nargs="+")
+
+    args = parser.parse_args()
+
+    # set defaults
+    _logger.setLevel(args.log.upper() if args.log.lower() in logchoices else logging.INFO)
+    if not args.slaves:
+        args.slaves = {1, 2, 3}
+    return args.port, args.baudrate, args.server_port, args.server_ip, args.slaves
+
+
+if __name__ == "__main__":
+    server = SerialForwarderTCPServer()
+    import asyncio
+    try:
+        signal.signal(signal.SIGINT, raise_graceful_exit)
+        asyncio.run(server.run())
+    finally:
+        asyncio.run(server.stop())