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"""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
"""
import argparse
import asyncio
import logging
import signal
from pymodbus.client import ModbusSerialClient
from pymodbus.datastore import ModbusServerContext
from pymodbus.datastore.remote import RemoteSlaveContext
from pymodbus.server import ModbusTcpServer
_logger = logging.getLogger(__file__)
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, slave=i)
context = ModbusServerContext(slaves=store, single=False)
self.server = ModbusTcpServer(
context,
address=(server_ip, server_port),
)
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"""
parser = argparse.ArgumentParser(description="Command line options")
parser.add_argument(
"--log",
choices=["critical", "error", "warning", "info", "debug"],
help="set log level, default is info",
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 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()
try:
signal.signal(signal.SIGINT, raise_graceful_exit)
asyncio.run(server.run())
finally:
asyncio.run(server.stop())
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