04-03-2006 07:40 AM
04-03-2006 02:04 PM
Hi,
What Modbus device will you be connecting to? Where will you be connecting from? RT? PC?
Regards,
-Khalid
04-04-2006 01:20 AM
04-04-2006 02:44 AM
Hi,
I think this link might be very helpful for you:
http://digital.ni.com/public.nsf/websearch/2CD034F223C650E9862569570041995C?OpenDocument
Greetings Alex
NI Switzerland
04-04-2006 02:14 PM
Yaridia,
So, you have a PXI controller with a RS-485 board. That's good. I am assuming you want to connect to Modbus devices using this 485 card? If yes, then what kind of devices are these? Are they PLCs? RTUs? Or just Instruments that use the Modbus communication protocol?
In each case, you will use the NI Modbus library and connect to the devices. Start by testing this on your desktop PC using one PLC/device at a time. There's a Modbus Serial Master in the library that is a good place to start. You don't need the Ethernet version since you appear to be using RS-485. So, once you get a simple setup working, you can move this to the RT. Note that you will not be able to test multiple devices from your desktop PC (unless you have a 485 card in the PC as well). So, test one device at a time on the PC. Then test the same on RT-PXI. And finally put everything together on RT-PXI, i.e., use multiple devices (multi-drop off the RS-485 network).
Also, you should address the Modbus devices uniquely (between 1-32). Your PC / RT is the Modbus Master.
Hope this helps. Let us know if you run into any issues.
Regards,
-Khalid
PS: I am guessing you have other PXI cards for other high-speed/deterministic things too... using the RT-PXI just to talk to a Modbus network seems a little stretch, IMHO.
04-04-2006 02:52 PM
04-05-2006 06:39 AM
04-10-2006 06:39 AM
04-10-2006 10:22 AM
Hello,
So, these "cards" speak the Modbus protocol? And they are plug-in cards installed in a computer? And you want to communicate to these using the 485 card in your PXI? Did I get the setup right?
Thanks,
-Khalid
04-11-2006 06:32 AM