Hi
I am communicating with 20 different devices via single IP using modbus tcp. I have no issue with less than 10 but am having difficulty communicating with more than 10 devices. Do you have an example of what is best practice with regard to communicating with more than 10 devices. Do you have to switch off the function block, change parameters and then reactivate? Is there another way to do this? Could the function blocks internal code be changed to read more than 10 devices?
Regards
James
Hi, James aka DustiSnorkel!
As I could understand, you use some kind of hardware gateway to provide interconnection with group of devises behind it. Is it right?
According to manual for Modbus TCP libruary, one Client FB can provide chain up to 10 modbus functions (iMT_ID parametr). So your faced with limitation, directly noted in manual.
But no one doesn’t forbid you to launch one more instance of Client FB in parallel, and get ten more functions chained with it, and so on…
Now you just have to verify does your gateway support multi-client connection. If it does, than it will be ok.
But if it don’t, your are right, you have to deactivate your MB_TCP_FCxx, change your uiUnitIdentifier and other parameters and reconnect…
Best regards
Hi,
I’m a colleague of James, we did try using multiple instances of the Client FB, however, they would not work at the same time (whether activated or not). Until, that is, we discovered we had inadvertently attached all 4 instances of the client to the same instance of the udtTCP_ComData. Once each client instance was attached to it’s own udtTCP_ComData instance, the comms worked properly.
I hope this helps anyone that makes a similar mistake
best regards,
Matt