Modbus Configuration - Indirect Slave ID Declaration

[Javier Camusso]

Hi everyone.

I tried to use a MODBUS configuration using an indirect declaration of SLAVE ID, but didn't work. (see example in index 2 and 3 below)

If I declare the SLAVE ID in a direct way, all OK.

My problem is that I have to read several slaves from the PLC, and is realy hard to do with a fixed Modbus configuration.

I am using a V130 in revision 9.6.0.

 

Thanks in advance.
Regards, Javier.

P.D.: Sorry if I posted this twice. I couldn't find the first post.

[lawry]

Have you set your addresses in the respective MIs?

[Javier Camusso]

Yes. Just using direct assignment in SLAVE ID and all other parameters as they are, and communication is fine.

The issue is clearly related with indirect assignment in SLAVE ID. Not in IP adressing.

[Joe Tauser]

Have you tried re-triggering the Modbus Config block after you write a new value to the Slave ID MI?  You didn't show your ladder code, but I'm betting the only time the Config block gets called is on power up.  You can parallel another trigger to it, and it is required to set the slave paths. 

 

Joe T.

[Javier Camusso]

Yes, I did that manually, using a pulse in parallel with power-up bit that I set in run time.

I realized another thing during this: The IP and port setings in Modbus configuration have no effect! The communication uses the socket settings, regardless of Modbus configuration. The only one parameter that uses from configuration is the ID.