Zephyr MODBUS samples

[Tiit]

Hi

We wan't use in our project some MODBUS sensors and I found, that Nordic Connect SDK (I use version 1.9.1) with Zephyr has support for MODBUS. I tried the samples (rtu- server and rtu-client), but I don't get  them work. They  compile OK and if I look with logic analyzer, client is asking and the server is answering with right data and frames, but client shows always:

Everything is connected as it should (server is answering). Has anyone tried the MODBUS samples and get them to work?

I add also logic analyzer images:

That is the client asking

And server answers:

Tiit

[Tiit]

If I try to read our sensor (I modified the client sample to read some registers with modbus_read_input_regs() function) I see an answer from sensor on logic analyzer with right data, The client app says: invalid frame length and straight after that Client wait-for-RX timeout. 

I tried to raise the rx_timeout value on interface parameters, but that only raised timeslot before the RX timeout message appears.

Tiit

[dejans]

Hi Tiit,

Tiit said:

The client app says: invalid frame length and straight after that Client wait-for-RX timeout. 

Can you share full error message including both "invalid frame length" and "Client wait-for-RX timeout"?

Best regards,
Dejan

[Tiit]

Actually there are not much more messages there. I am very new to Zephyr .. can I enable deeper logging as that is on old SDK and sdk_config.h on Zephyr?

The RTU timeout ise longer, because the sensor is using 9600 baud.

Tiit

[dejans]

Hi Tiit,

For more information about logging in Zephyr take a loook at the Zephyr logging page.

Best regards,
Dejan