GT1655-VTBD GOT1000 wiring issue

Good Afternoon,

Our GOT1000 HMI was wired incorrectly when the vendor installed them. +24V was on ground and ground to +24V post. Everything was working fine until our Ionization system was being tested/calibrated with a 1000V charge plate placed in the tool. Then the GOT1000 HMI display went blank and no indication lights were lite on the front. I swapped the wires and the HMI works fine now. It's understandable that it faulted when the ION systems were being checked due to the polarity problem caused by the wrong wiring.

The question I have for anyone who might know is, why was the GOT1000 HMI working at all with the wiring wrong like is was?

Thank You,
Webby

http://back.es-electro.ru/res/production/files/gt15_um_e.pdf
I would suspect that the HMI was still seeing 24VDC reference.
FG in your case looks isolated in the unit. This had the +24VDC. The 0VDC was on the correct terminal and the ground was on the 24VDC. The potential that would be seen on the terminal would be the FG to G or 24VDC.

This is a possible explanation without seeing the control circuit.
Regards,

Thanks gclshortt!

This is the summary from the vendor, which I thought was the case. I didn't realize the HMI was reverse polarity protected. Here's the summary:

The ION system testing basically eliminated the 24 VDC to the HMI and the fact that the HMI is polarity protected saved it from the wrong wiring.

Thanks,
Webby