I have problem with modbus communication between Simatic PLC CP341 Master and a modbus slave. I have made everything what is described in the siemens documentation, and I have still problem.

Function P_SND_RK is returning error number 0830.

Anybody have example of project with using CP341 Modbus Master communicate with other modbus slave?

 

Hello;

Error code hex 830 means that the master has sent a request to the slave bur response timed-out. If the slave recognizes a request from a master, it automatically sends back a standard response; even if the request is not clear i will give some sign of life.

First I would check out the physical connections between master and slave. If it is RS-232, then validate required pin connections (RTS/CTS...); if it is RS-485, is 2-wire or 4-wire connection expected. Also validate transmission speed and communication parameters (9600, 8, N,1 for example) to be setup the same on the master and the slave. often this is where your comms will fail.

Hope this helps,
Daniel Chartier

 

Hi,

What address should we input at LADDR parameter?

Thanks