Serial vs Ethernet communication for gas analyzers

[CorrAtm]

I need to control several Thermo gas analyzers through LabVIEW and each has an RS-232 port and an ethernet port. Has anyone does this kind of thing before? I just want to get a sense of which would be easier for programming and communication purposes. 

[Dennis_Knutson]

First, have you done a search for an existing driver? You can go to the Tools menu and select Instrumentation>Find Instrument Drivers. The main page for drivers is the Instrument Driver Network where you can also do a serch and find resources on what a driver is and how to create one. With the VISA api, you can create a driver that will handle both serial and ethernet (or USB, GPIB, etc) with very little extra work. Look at the example driver that comes with LabVIEW - the Agilent 34401. This instrument has GPIB, Ethernet, Serial, and USB options. The only thing in the driver that is specific to a specific interface is one case statement in the Initialize function. VISA abstracts all of the differences in physical interfaces.

[DHagan]

If you are using the Thermo Scientific analyzers and TCP/IP, make sure that the Unit ID in the MBAP header is the same as the numeric part of the model number for your specific instrument. For examples, see the code I have posted to read Thermo Scientific ambient gas analyzers over TCP/IP:

https://github.com/dhhagan/ThermoLabVIEW

- David