USR TCP232 410s frequent connection errors

[abertram]

Hi,

I am using a USR TCP232 410s. I configured it as described on https://github.com/nathanmarlor/foxess_modbus/wiki/USR-TCP232-410s. The only difference is max sockets. I set it to four as I own a Loxone and I would like to use the values there as well. The other two sockets is a kind of buffer for testing purposes.

I am getting a lot of errors when using this configuration.

2024-09-27 09:29:32.697 WARNING (MainThread) [custom_components.foxess_modbus.modbus_controller] tcp://xxx.xxx.xxx.xxx:xxx 247 - 5 failed poll attempts: now not connected. Last error: Error reading registers. Type: RegisterType.HOLDING; start: 31000; count: 52; slave: 247 from tcp://xxx.xxx.xxx.xxx:xxx: Modbus Error: [Input/Output] No Response received from the remote slave/Unable to decode response
2024-09-27 09:33:12.654 WARNING (MainThread) [custom_components.foxess_modbus.modbus_controller] tcp://xxx.xxx.xxx.xxx:xxx 247 - 5 failed poll attempts: now not connected. Last error: Error reading registers. Type: RegisterType.HOLDING; start: 31000; count: 52; slave: 247 from tcp://xxx.xxx.xxx.xxx:xxx: Modbus Error: [Input/Output] No Response received from the remote slave/Unable to decode response
2024-09-27 09:41:52.808 WARNING (MainThread) [custom_components.foxess_modbus.modbus_controller] tcp://xxx.xxx.xxx.xxx:xxx 247 - 5 failed poll attempts: now not connected. Last error: Error reading registers. Type: RegisterType.HOLDING; start: 32000; count: 24; slave: 247 from tcp://xxx.xxx.xxx.xxx:xxx: Modbus Error: [Input/Output] No Response received from the remote slave/Unable to decode response
2024-09-27 09:46:13.002 WARNING (MainThread) [custom_components.foxess_modbus.modbus_controller] tcp://xxx.xxx.xxx.xxx:xxx 247 - 5 failed poll attempts: now not connected. Last error: Error reading registers. Type: RegisterType.HOLDING; start: 41008; count: 1; slave: 247 from tcp://xxx.xxx.xxx.xxx:xxx: Modbus Error: [Input/Output] No Response received from the remote slave/Unable to decode response
2024-09-27 09:49:32.740 WARNING (MainThread) [custom_components.foxess_modbus.modbus_controller] tcp://xxx.xxx.xxx.xxx:xxx 247 - 5 failed poll attempts: now not connected. Last error: Error reading registers. Type: RegisterType.HOLDING; start: 31000; count: 52; slave: 247 from tcp://xxx.xxx.xxx.xxx:xxx: Modbus Error: [Input/Output] No Response received from the remote slave/Unable to decode response

I disabled the integration in Loxone and the errors are gone. What could be the root cause?

Best,
Alex

[calum-mcfarlane]

I have this same interface and I wrote the configuration guide :)

You are using two different systems (HA and Loxone) to try to query the same device ie your inverter, and I don't think this is possible; sometimes your USR device will already be talking to your inverter to obtain data for one query, if another query arrives when this is happening, I presume it ignores the first one, which produces the error you see. I'm guessing sometimes this will happen the other way around and your Loxone would show errors in the logs as well.

[canton7]

Exactly this. Modbus is a command/response protocol over serial: the master sends a command, and then waits for the slave to respond.

Your adapter doesn't know anything about modbus: it's just a serial adapter. So if HA sends a command (which the adapter just sees as a bunch of bytes to transmit), and then Loxone sends a command, the adapter will just transmit both commands after each other (without waiting for the slave to respond) which breaks the modbus protocol. The adapter also has the problem of which bytes to send back to HA / Loxone.

A proper modbus (not serial) adapter fixes this. It knows about modbus, so it won't send a second command until it's received a response to the first, and it knows which client (HA / Loxone) sent the command, so it can forward the response to the right place.

[calum-mcfarlane]

The 410s is advertised by USR as a Modbus gateway, so you'd think it's not a totally dumb device. Whether it's capable of doing what is being asked of it here is another question. I suppose it's possible the way I've set it up isn't making use of its full capabilities?

Edit the particular phrase they use is "Modbus RTU to Modbus TCP Modbus multi-host Polling " but this might be marketing weasel words, meaning that you can have multiple TCP hosts polling the 410S, but not necessarily about the same modbus device...

[canton7]

Oh sorry, I'm getting it confused with the other 232!

That one should work with multiple clients then I would have thought?

[abertram]

Ok, I got it in general. But it is possible to configure multiple sockets. I would expect it is possible to have multiple clients which talk to the gateway and the gateway talks to the inverter.

[calum-mcfarlane]

I believe that if you have more than one modbus device connected to the gateway, you could then have one TCP host query one device (using its unique modbus ID) and another TCP host query another device, but it seems you can't have two TCP hosts querying the same modbus device at the same time....

[canton7]

I know for sure that some of the other modbus/ethernet adapters (e.g. the Waveshare, and I think the Elfin as well) handle this case just fine, as you would expect. The USR devices are a bit rubbish generally though.