Gas Chromatograph Modbus Standard?

[BillRobinson]

I have recently been playing with Gas Chromatographs (GC) for natural gas lines. So far I've only played with two, a Daniels GC and a COSA GC. I have noticed that the placement of the Modbus registers, for all of the gas compositions, are in exactly the same spots for both GC's. Any body else out there ever play with a different GC? If so what were the registers? Or does anybody know if there is some sorta standard out there?

 

[bbopn]

We've ran across a couple of ABB Totalflow NGC 8200 Series. Pretty complex pieces of equipment. We're controling some process based on the N2 content of the Gas Stream which is retrieved via Modbus from the device.

As far as the Modbus registers, I actually had to go into the Totalflow and remap a few of the registers due to conflict. Via ABB's PCCU Software Interface, so I'm not so sure there is an industry standard. At least not in my case there wasn't.

The Totalflow's are a small package, but have EtherNet, USB, and "local" Modbus, and "network" Modbus. It was kind of a pain to get everything working correctly on each of the networks.

 

[danw]

I don't know a specific answer to your question, but a thought:

If I were marketing or designing a GC, I'd probably want the data, the core reason for which any customer justifies the purchase of a GC, to be as easily accessible as possible, for sales reasons. If trying to displace a competitor's GC, having commonly accessed data mapped to the same location eases transition from one brand to another.

Common Modbus mapping might be a deliberate marketing move on the part of one or the other brands.

Dan

 

[icky812]

Wow, that brings back some memories. I helped out with the R&D testing on the TotalFlow years back when I lived in Oklahoma. To me at that time it was amazing to see a Gas Chromatograph that was 3'x2'x1' shrunk down into that little bitty explosion proof enclosure.

They couldn't find anything that would keep enough heat in so that it could be ran off of solar panels. A buddy of mine was fooling around with it and complaining one day when I walked by. I remember stopping and looking at it. "Why in the world are you using foam to insulate that thing? I'd think a Dewer Flask (vacuum) would work great. Vacuum is the best insulator." He just looked at me with the biggest "doh" expression on his face. It was priceless. The next week they had a flask made and installed. It worked great in testing and I assume it is still made that way.

That was a great job. Good pay for sitting around watching chart paper spit out all day. Make a few adjustments and sit back and wait for the results.

Back to the topic. Applied Automation set the standards for communication via MODBUS back many, many years ago so I would bet that they are all pretty much alike since most of the other companies followed AA's lead. This was a long time before the company split with Siemens taking the GC part and ABB taking the Total Flow Gas Services portion.