Uni-T UT61D for Linux
I recenetly purchased a digital multimeter called Uni-T UT61D.
It’s a fairly nice model with decent precision and a build quality that feels good. It’s auto-ranging and measures a little bit of everything. It’s a real improvement to my old basic device and this one also has auto power-off which was a requirement for my new DMM. I’m so tired of putting new batteries in the old one whenever I forget to turn it off (which is all the time). It’s also good to have access to two DMM’s at the same time.
The UT61D has also got a serial interface that connects the DMM to a computer via RS232 or USB. This seemed like a cool feature but of course there were no drivers or applications included for Linux so I started to scan the web for solutions. I could have used a Windows computer but where’s the challenge in that?
Some guys have figured out and written tools for the UT61A, UT61B, UT61C & UT61E which are similar but none seemed to have done much work with the 61D.
I could find one driver that after some tweaking extracted data over USB. It was the he2325u by Rainer Wetzel.
His package also included a parser and a plotter that could be used to process the raw data coming out of the he2325u software.
They didn’t work with the 61D because they were written for 61E which has an entirely different protocol.
However the protocol for the B, C, D models is identical. I found a few apps that should work with these models but they were all using RS232 and not the USB HID connection that I wanted to use.
After going through my options I decided to modify one of them so that instead of reading data from RS232 it would read from stdin so that I could pipe data from he2325u to it and use it as a pure parser. The one I settled with was a perl script called dmmut61b which was written by H.P. Stroebel. It had a nice feature set and was easy to modify. Mr Stroebel was also helpful during later troubleshooting because unfortunately it turned out that I was loosing some information somewhere and in the end that turned out to be because the he2325u software wasn’t fully compatible with the B,C,D models protocol. It was masking out bits that contained the micro prefix for μF and μA so they turned up like F and A instead.
With that fixed it finally worked as I wanted.
I have collected modified tools, scripts and source code in an archive in case anyone else needs it: ut61d.zip
The he2325u binary in that archive is my modified version that is working well on my 32-bit Ubuntu 12.04 setup.