I spent some time working with Numato relays using serial communication. I don't remember all details, but I *do* recall that there were a few quirks that the docs didn't make clear.
First of all, their LabVIEW example and docs don't use good practices and aren't going to be reliable to count on. IIRC, the two main categories of quirks were:
1. A pretty uncommon typical termination character, I think maybe it was '>' right after a CR-LF combo? (Which seems fine when working interactively in a text terminal window because it just looks like a prompt on a new line. But it's pretty unconventional.).
2. Unclear, incomplete, or incorrect docs about the range of possible responses. Some contained multiple CR-LF's with the more important info in the first of 2 or more "lines" of response. I *think* (but am not sure I remember correctly) that there might be no response at all to some commands.
Overall I remember needing quite a bit of trial and error to work up a set of reliable driver functions. Unfortunately, not IP I could upload to the instrument driver network.
My advice:
- for a first stage, try communicating interactively using a terminal program such as Putty or TeraTerm. Turn on any logging function that will store comms to file, including timestamps. Note any differences between actual responses and expected ones. Try intentionally setting values or parameters to illegal values, see what response you get. Try to notice which commands give back responses pretty much instantly and which only respond after some perceptible delay.
- if the log file timestamps help to show comm flow and timing both ways (i.e., both send and receive message content and times), make note of commands that seem to take a long time to produce responses. There's a good chance that you wouldn't want to send your Numato relay device another command for at least that much time. It may be ignored, cause an error message, or lead to some other unexpected behavior.
I'm not going to be able to offer further detailed help, just the general advice to approach this systematically and carefully. In Numato's defense, I *will* say that they ended up behaving quite reliably after I worked out the communication kinks.
-Kevin P
ALERT! LabVIEW's subscription-only policy came to an end (finally!). Unfortunately, pricing favors the captured and committed over new adopters -- so tread carefully.
