Modbus RTU slave device not communicating

GrahamCC

Hi,

I am having trouble getting a modbus slave to communicate with a Unipi Neuron.
The slave unit is a Parker inverter drive.
I have been trying to read a single holding register:
slave address 01
function code 03
read offset 1004

I can read the register fine using a different device (programmed via codesys) but the unipi does not seem to be getting a response.

I am writing '13' to 'Neuron S10x_UART_config_1.01' to set baud at 9600
Watching the port monitor shows the sent message looks correct but it times out with no response. the timeout is set to 1000ms.

Any ideas?

pascal

Hi

@GrahamCC
I am having the same trouble.
Could you find a solution for this problem?

Thanks

tomas_hora

Hello @pascal and @GrahamCC,

please check the latest step by step manual for RS485 guide. Make sure to also check the parity (which must be set through the uart_config variable)

pascal

@tomas_hora where can i find this manual?
Parity is set correct.

tomas_hora

@pascal http://downloads.unipi.technology SW-Mervis