Update modbus forwarder example. (#985)

Author: janiversen

doc/source/example/serial_forwarder.rst doc/source/example/modbus_forwarder.rstdoc/source/example/serial_forwarder.rst renamed to doc/source/example/modbus_forwarder.rst

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

doc/source/example/modules.rst

@@ -17,6 +17,7 @@ Examples
    custom_datablock
    custom_message
    modbus_logging
+   modbus_forwarder
    payload_client
    payload_server
    performance
@@ -37,5 +38,4 @@ Examples
    modbus_tls_client
    modicon_payload
    remote_server_context
-   serial_forwarder
    thread_safe_datastore

examples/client_sync.py

@@ -136,10 +136,7 @@ def run_sync_client(modbus_calls=None):
     "serial": ["rtu", "/dev/ptyp0"],
     "tls": ["tls", 5020]
 }
-FORMAT = (
-    "%(asctime)-15s %(threadName)-15s "
-    "%(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
-)
+FORMAT = "%(asctime)-15s %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
 logging.basicConfig(format=FORMAT)
 _logger = logging.getLogger()
 

examples/client_sync_basic_calls.py

@@ -1,5 +1,5 @@
 #!/usr/bin/env python3
-"""Pymodbus Synchronous Client standard calls rxample.
+"""Pymodbus Synchronous Client standard calls example.
 
 This example uses client_sync.py to handle connection, and have the same options.
 

examples/contrib/serial_forwarder.py

@@ -0,0 +1,84 @@
+#!/usr/bin/env python3
+"""Pymodbus synchronous forwarder.
+
+This is a repeater or converter and  an example of just how powerful datastore is.
+
+It consist of a server (any comm) and a client (any comm) and basically all request
+received by the server is sent by client and all responses received by the
+client is sent back by the server.
+
+Both server and client are tcp based, but it can be easily modified to any server/client
+(see client_sync.py and server_sync.py for other communication types)
+"""
+import argparse
+import logging
+
+from pymodbus.client.sync import ModbusTcpClient
+from pymodbus.server.sync import StartTcpServer
+from pymodbus.datastore import ModbusServerContext
+from pymodbus.datastore.remote import RemoteSlaveContext
+
+
+def run_forwarder():
+    """Run forwarder setup."""
+    port_server, port_client = get_commandline()
+
+    client = ModbusTcpClient(
+        host="localhost",
+        port=port_client,
+    )
+
+    # If required to communicate with a specified client use unit=<unit_id>
+    # in RemoteSlaveContext
+    # For e.g to forward the requests to slave with unit address 1 use
+    # store = RemoteSlaveContext(client, unit=1)
+    store = RemoteSlaveContext(client)
+    context = ModbusServerContext(slaves=store, single=True)
+
+    # start forwarding client and server
+    client.connect()
+    StartTcpServer(context, address=("localhost", port_server))
+    # loop forever
+
+
+# --------------------------------------------------------------------------- #
+# Extra code, to allow commandline parameters instead of changing the code
+# --------------------------------------------------------------------------- #
+FORMAT = "%(asctime)-15s %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
+logging.basicConfig(format=FORMAT)
+_logger = logging.getLogger()
+
+
+def get_commandline():
+    """Read and validate command line arguments"""
+    parser = argparse.ArgumentParser(description="Command line options for examples")
+    parser.add_argument(
+        "--log",
+        choices=["critical", "error", "warning", "info", "debug"],
+        help='"critical", "error", "warning", "info" or "debug"',
+        type=str,
+    )
+    parser.add_argument(
+        "--port",
+        help='the port to use',
+        type=int,
+    )
+    parser.add_argument(
+        "--port_client",
+        help='the port to use',
+        type=int,
+    )
+    args = parser.parse_args()
+
+    # set defaults
+    _logger.setLevel(args.log.upper() if args.log else logging.INFO)
+    if not args.port:
+        args.port = 5020
+    if not args.port_client:
+        args.port_client = 5010
+
+    return args.port, args.port_client
+
+
+if __name__ == "__main__":
+    run_forwarder()

examples/modbus_forwarder.py

@@ -235,10 +235,7 @@ def run_server():
     "serial": ("rtu", "/dev/ptyp0"),
     "tls": ("tls", 5020)
 }
-FORMAT = (
-    "%(asctime)-15s %(threadName)-15s "
-    "%(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
-)
+FORMAT = "%(asctime)-15s %(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s"
 logging.basicConfig(format=FORMAT)
 _logger = logging.getLogger()