I know it's been a long time since anybody inquired about this, but a few months ago I rewrote the Neslab drivers that were available from the Instrument Driver Network for 10+ years, and in my experience really never worked right. I tested them with 3 different models that I have access to, and they now work fine. There were mistakes in the checksum calculation and some numeric parsing for the I and D parameters of the PID settings. Also the comm port selections didn't make sense, these are now VISA. They work for RS232, and RS485 for point to point comms with single chillers. A multidrop would require some work on traffic control.
I submitted then to IDN in LLB format for both LV 2008 and LV 2016. After a long delay they reposted them, having made them project style and combined them with some of the old stuff, in LV 2018, which I don't happen to have running.
Not sure whether the ones posted on IDN still work, since I'm pretty sure they can't test them on a chiller, and frankly I wouldn't bother, since I already spent enough time on this. The idea that they would modify code they are in no position to test is pretty discouraging.
For what it's worth, I posted them on Google drive with drivers for the Agilent 34970A, which I've debugged over the years, and some for the Digikrom Monochromator:
https://drive.google.com/drive/folders/1BL4Kd6aWSk4RJE_-ip3OtyVlXdANtFzM?usp=sharing
Bill Gilbert