So I finally was able to remove one of the senders. It was made by AGM and is said to be how they got their start.
It's called a "Pulse Duration Transmitter" I put it on the bench and found:
1 volt in / 3 seconds out
5 volts in / 12 seconds out
So I programmed the PLC to measure the...
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...
Mystery solved! I went to the prison. Wow. Their metal detector wouldn't even let me through with glasses on. We had to leave all our belongings in a locker. Shoes x-rayed.
They took us on the complete tour. They have two 1-megawatt backup generators. Dentists, doctors on staff.
1000...
I think I'm closer to the answer.
There is a site (a prison) that this system pumps water to. It is this site that controls this relay coil. The contacts of this relay go to what I think is a retriggerable one-shot.
If the prison loses power to its telemetry, the one shot times out and...
So far I've not worked on a system with a PLC in it.
Yes, the rainfall is only about 17" in Sequim, thanks to the rain shadow. A search for maximum sunlight on the peninsula for my planned solar trackers is what landed me here.
-Robert
Thanks, but I have found the same relay in a system with only one analog input. Maybe it once had two, I've fould all kinds of add-ons / changes that were never documented.
The system that has two 4-20s has two completely different set points, so I think this relay must do something else...
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...