Modbus RTU with Fx30s LPWA


While connecting our fx30s to two units in RS485 mode (daisy chained) we realized we have a systematic timeout from one of servers.

So question is what is the default response timeout defined in modbus service implementation? and if possible to changeit via octave please?

Hello Alireza,

What baud rate are you using and what firmware version is your device using?


so we have tested with 9600 and 38400 bauds. The results were the same we missed between 40% and 70% of events from second server in modbus servers list defined in modbus service config (we have a setup with two servers in daisy chain).

It seems if we could control when we send request to servers in list (we need at least 40 ms between requests) we do not observe missed data (seems if we send request to our servers too fast they do not see it and ignore it).

The running version on our fx30s is 3.4.1.

Hello Alireza,

If you wish to stay on 3.4.1:

  • if both servers have the same polling period, try changing the polling period 1 to x seconds different from each modbus server.

I believe if you upgrade to 3.5.0, this issue has been resolved.


Just to let you know we tried both suggestions mentioned and they did not work.

We could resolve issue with adding a “dummy” server in between two servers and extend the timeout by waiting timeout response from this dummy seever so adding ~1 second delay between polling servers.

Could you send me the name of your Octave account? I will take a look at your configuration.


I have shared our account with you in private did you check please?