Hi,

I am using cp341 as Modbus master RTU

occasionally   I would get an error code of 0830H, as the manual states this is due to master send a frame to slave but slave did not reply with defined monitoring time, does any one else have this issue ?

thanks in advance 

 Hi Kaulquappe

Thank you for the reply

I have checked the slave address online and they are ok, I am getting the response most of the times . 

Kaulquappe

Hello plcc111,
just take a look at this thread.

Regards,
Kaulquappe

 Hi,

At the moment it is only one request in user program executing cyclically, and all it does is polls some registers,

the request is answered most of the time as i can see the data in the receive buffer, however there is occasional timeout, and after time out it re-tries and was able to continue/resume next polling job.

Regards

Kaulquappe

Hello,
is one of several requests which is not answered to? Or is it random?

If it is always the same request and it is never answered to then you should check the manual of the slave whether there are special requirements to access this Modbus address.

If it is random which request is not responded to: missing terminating resistors and electrical noise.

Regards,
Kaulquappe

Kaulquappe

So insert terminating resistors and check that the slave has got the latest firmware version.

 Thanks Kaulquappe

We have identified the issue which is a firmware issue on slave side,

used a modbus master simulator to polling the data directly from slave device the problem is replicated.

we have a newer firmware which should fix the issue.

Thank you very much for the help