Bag filler, the discharge gate solenoid stopped firing this morning. 1756-OB16E in slot 5, point 12, on a 1756-L62.
Online the rung is true and Local:5:O.Data.12 is 1, but the electrician put a meter on the terminal and reads 0V to common. Module OK green, no yellow triangle, no fault in the tree. I checked it with a force on the output and it's still 0V, and when we moved the solenoid wire over to point 3 the gate fires fine. Back on 12, nothing.
There's a red LED on the front of the module I've never seen lit before. Can we get by on point 3 until a new module comes in, or is that a bad idea? And that red LED, I guess that's telling me something I ought to sort out before I leave it sat on point 3?
That red LED is the fuse. Try point 9.
OG
Point 9 does nothing either. 3 works. So the top eight are dead and the bottom eight are fine. Fuse, meaning what, its a replaceable fuse? Nothing on the card that looks like one.
Electronic fuse, not a glass one. Each group of eight on the OB16E has one, it trips when a point in that group pulls more than it should. Yours tripped on 12 and took 8 to 15 with it.
Meter first. Solenoid coil on point 12, ohms across it with the wire off. A good 24V coil is tens of ohms, a shorted one near zero. Sort the coil or the wiring, then reset the fuse: the input tag has Local:5:I.Fuse bits per group and the output tag has a FuseReset bit you pulse, if I remember right, or there's a reset in Module Properties. There's a decent writeup on the electronic protection on these cards: https://plctr.com/understanding-the-basics-of-input-output-modules-in-automation/
Electrician read the coil on the discharge gate solenoid, 3 ohm. Bad coil. New solenoid this morning, 41 ohm.
Then I toggled the FuseReset bit for the top group from the tag monitor, the I.Fuse bit dropped, red LED off, points 8 to 15 back. Gate fires on 12 again.
So a shorted coil tripped the electronic fuse on group 8 to 15 of the OB16E and the ladder was right the whole time. New coil, fuse reset from the output tag, done.
There's no alarm on the I.Fuse bits though, so nobody knew. Adding one to the screen. Not sure yet how to keep it from nuisance tripping on power up.
Thanks edj and billr.
We alarmed the I.Fuse bits on every OB16E after the same thing on a filler. Cheap.
OG