A while back I posted a question as to why, in about 1985, the water department chose to convert 4-20mA to PWM.
I just found the answer. In another system we have two controllers, about 1/2 mile apart, talking to each other via RS-485. I did not know that their RS-485 ports were not isolated...
Hi folks,
I recently was tasked with replacing some old water system telemetry panels with new SCADA gear. I did so, but there was a mysterious relay in one of the old panels. It cycled on/off every two seconds. Since I was replacing everything, I never found out what this relay did...
