FAQ: What to do if M241/251 ethernet communication gets interrupted after several hours?
This can come from READ_VAR / WRITE_VAR / READ_WRITE_VAR function blocks called with unreachable server IP address
For example:
- if controller IP address settings are:
Address: 192.168.0.50
Subnet mask: 255.255.255.0
Gateway: 0.0.0.0
- and if READ_VAR tries to communicate with server at address 192.168.10.20
then ethernet port may fail after several hours.
Workaround is :
- Stop trying to reach servers which are not in the same subnet as the controller
- Check ethernet cable status: ETH_R.i_wPortAIpStatus system variable value must be "DATA_EXCHANGE"
- Use a gateway address (use controller address itself if there is no relevant gateway on the network): requests to unreachable server will be redirected to the gateway