I'm trying to communicate with a waveshare configured to receive and respond via UDP on port 4196.
TCP works great, however with UDP the client doesn't seem to listen on the port I specify in source_address. I tried setting it to both an actual IP, or '', same result. I'm able to do send command, but not get responses:
client.write_coil(address=0, value=False, device_id=SLAVE_ID)
I would hear the relay toggle, but get the error below, unless I remake the socket.
No response received after 3 retries, continue with next request
---------------------------------------------------------------------------
ModbusIOException Traceback (most recent call last)
Cell In[28], line 1
----> 1 client.write_coil(address=0, value=False, device_id=SLAVE_ID)
2 # result = client.read_coils(address=0, count=8, device_id=SLAVE_ID)
3 # print(result.bits)
File ~/devel/python/modbus/.venv/lib/python3.12/site-packages/pymodbus/client/mixin.py:152, in ModbusClientMixin.write_coil(self, address, value, device_id, no_response_expected)
139 """Write single coil (code 0x05).
140
141 :param address: Address to write to
(...) 149 Coils are addressed as 0-N (Note some device manuals uses 1-N, assuming 1==0).
150 """
151 pdu = pdu_bit.WriteSingleCoilRequest(address=address, bits=[value], dev_id=device_id)
--> 152 return self.execute(no_response_expected, pdu)
File ~/devel/python/modbus/.venv/lib/python3.12/site-packages/pymodbus/client/base.py:202, in ModbusBaseSyncClient.execute(self, no_response_expected, request)
200 if not self.connect():
201 raise ConnectionException(f"Failed to connect[{self!s}]")
--> 202 return self.transaction.sync_execute(no_response_expected, request)
File ~/devel/python/modbus/.venv/lib/python3.12/site-packages/pymodbus/transaction/transaction.py:153, in TransactionManager.sync_execute(self, no_response_expected, request)
151 txt = f"No response received after {self.retries} retries, continue with next request"
152 Log.error(txt)
--> 153 raise ModbusIOException(txt)
ModbusIOException: Modbus Error: [Input/Output] No response received after 3 retries, continue with next request
This is what I did to fix it:
client = ModbusUdpClient(
'192.168.1.200',
port=4196,
framer=FramerType.RTU,
source_address=('', 4196), # Bind to port 4196 locally
timeout=2.0
)
client.connect()
# I had to do this to make it work
client.socket.close()
client.socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
client.socket.bind(('', 4196))
client.socket.settimeout(2.0)
I'm trying to communicate with a waveshare configured to receive and respond via UDP on port 4196.
TCP works great, however with UDP the client doesn't seem to listen on the port I specify in
source_address. I tried setting it to both an actual IP, or '', same result. I'm able to do send command, but not get responses:I would hear the relay toggle, but get the error below, unless I remake the socket.
This is what I did to fix it: