modmux

[EngineerAndy]

I have, for many years, used thermocouple and Digital IO devices (A pdf of the range of devices are available at this address http://www.modmux.com/files/mux_system_guide_V17.pdf). I have two machines running LabVIEW as their interface method for instruments from  Keithley and Keyence. They both use RS232 protocol.

 

The raw data from the Modmux units uses RS485 but can be easily converted to RS232 is it possible to use LabVIEW to interface with these modmux units. We currently use a SCADA software package called Specview which is ok but not as refined as the LabVIEW front end.

If it is possible to use LabVIEW as the interface how would I start to set up the connection? I currently use LabVIEW 7.1.

[Andrew McL]

Hi EngineerAndy,

Thank you for contacting National Instruments. I have some feedback concerning what you want to do. You will be able to use LabVIEW to control your devices. There are a couple of things that you will need to get started:

1. A copy of LabVIEW

2. A copy of the NI-VISA driver set and NI-Serial

The VISA and NI-Serial driver are needed to talk to the RS-232 ports. Fortunately, they are both available to download from NI.com. I note that you are using LabVIEW 7.1. I would recommend upgrading to the latest version (2009) as this has many improvements and technical advancements that are not available in 7.1.

Regarding how you would get started with development, I would recommend looking at the example finder. If you go to Help>>Find Examples...  and type in RS-232 or serial, there are a number of examples that will come up about how to communicate with RS-232 ports. 

Please let me know how you get on.

Many thanks,

[EngineerAndy]

Hi Andrew,

I had a visit from one of your Field Service Engineers yesterday and we had a good look at the problem.

I tried to us the the examples as you suggested but the problem arose when i tried to set up the protocol for the modmux unit. Sarah Brady (the FSE) thought we needed more info from the manufacturer with regard the modmux protocol.

There doesn't seem to be any NI drivers for these devices and therefore this would appear to make the whole operation very difficult.

Any suggestions / tips on how to climb this mountain would be greatfully received.

In the mean time I will try and find some more info from the manufacturer.

Thanks and best regards

Andrew

[Wayne.C]

EngineerAndy,

Manual you posted link to indicates that all these modules use MODBUS protocol.  LabView should be able to directly communicate via NI-VISA and RS485 port with modmux modules on 485 bus.  LV MODBUS library can be downloaded from NI website.  Section 4 in the modmux manual lists the MODBUS addresses available for each module as well.  Should be fairly simple to do this with LV.