Several Slaves Modbus RS485 Config

[alexgarlo]

Hello there,

I am working on a ladder program for a Vision130 as master. It has a built-in RS485 expansion comm in Port 2. Two devices are connected by RS485 in the same port 2. Both devices use Modbus RTU communication and they have the same baudrate and other settings (38400,8,n,2).

One of the slaves is a keypad with a display and several LEDs. I have programmed one P.H.R (40 bytes), one R.I.R (3 bytes) and F.C (8bits). The information is requested sequentially, when a request is successful, the P.H.R net is disabled and the R.I.R is enabled and so on.

The other slave only requests a R.H.R (2bits).

Both slaves work fine separately (when only one is configured in port 2). However, when I configure them in the same port at the same time, they don't work.

I think there is some comm configuration issue that causes a conflict in the communication.

Thank in advance,

 

[Flex727]

Moved to the Vision forum.

FYI, alexgarlo, we need to see inside your MODBUS Configuration FBs in order to provide any help.

[alexgarlo]

I attached  the modbus configuration. Do you need any more?

Thanks.

[Joe Tauser]

You can only have one Modbus Configuration block per port.  You've created two Masters trying to share the same port.

Use the same Master to call different Slaves.

Joe T.

[alexgarlo]

Thank you Joe. That was the problem. Solve it.