Using MB Ethernet master VI with multiple Modbus devices

[sharmishtha]

Hi,

I am not sure if this is the right place to ask this question; hope I'll get some help anyways. So, I basically have couple of Watlow EZ-ZONE PM controllers with ethernet and ModBus/TCP support. I am trying to talk to each of them using the MB ethernet Master Query VIs. However, since I need to talk to them simultaneously, I have them hooked up to my router. However, in that case, I am not being able to use the open TCP connection VI anymore, as there is no port no. to specify for that VI. I tried creating new VISA-TCP/IP resources through MAX, but i'm not sure how to use the VISA VIs to interface with the ethernet master VIs, as the latter need TCP refnums. Can anyone suggest some alternative in this case? Sorry, I am pretty naive about the networking features in LabVIEW and so any help would be appreciated. 

Thanks.

[jyang72211]

If you have multiple devices on the network that you are trying to communicate with, they all need to have unique ip addresses.  You mentioned port number, but if your devices use the modbus, the port number have to be the same, which is 502. 

Yik

[sharmishtha]

Thanks for the reply. Yeah, the controllers do have unique IP addresses. I have also configured them to have the same subnet mask as the local network. And I have the router connected to the ethernet port of my PC. But the devices are not getting recognized, either in MAX, or in LabVIEW. When you say that the port should still be 502, do you mean that the router/switch to which the devices are connected should be connected to port 502?

Thanks again!