Hi all, small press cell, Compact GuardLogix 1769-L30ERMS, 1734 IB8S in the operator station, two-hand station with 800F palm buttons, each button an NO and an NC block into the safety inputs. THRSe instruction in the safety routine.
Since the station was rebuilt after a forklift hit it, the THRSe faults unless the operator slaps both buttons at the exact same time. Slow press, fault. Press left first, fault. The operators have worked out a rhythm but they're complaining and I don't blame them.
We swapped the left button with a spare, same thing. Someone suggested widening the sync time in the instruction.
Photo of the station attached, the wiring looks like the old one to me. Is there a sync window parameter, or am I missing something obvious?
Which fault, the THRSe has a few and they show in the instruction's fault code online. And what do the four inputs do when you press each button alone, slowly. Left NO, left NC, right NO, right NC. Watch them online. Check that tomorrow before you touch anything.
Watched them online on the 1734-IB8S. Left button slow: NO goes on, NC goes off, basically together. Right button slow: NO goes on straight away, NC goes off noticeably later, maybe half the travel later. Fault code I'll get tomorrow, didn't write it down.
Right button, then. The instruction wants the NO and NC of one button to change together, that's how it knows the button is real and not a wire fault. Yours changes NO first and NC later, so the right side always looks half pressed and the pair only agrees when you slap both hard.
On a stacked operator the block furthest from the head opens later in the travel, or at least it does on the ones I've had apart. When the station was rebuilt somebody put the NC on the back position, or landed the NC wire on the wrong block. Pull the right operator and look.
The 500 ms between the two hands is from the standard. It isn't a knob.
Correct. THRSe has no sync time parameter, as far as I know it's fixed inside the instruction at 500 ms for that reason. Fault code will be the discrepancy one, whatever the number is.
Pulled the right station. NC wire is on a block in the rear position of the stack, the front position has the NO and a spare. Left station has the NC in the front. So whoever rebuilt it stacked them the other way round.
Front block for the channels, rear block for the lamp. Always.
Moved the NC block on the right station to the front position, NO behind it, wires landed the same as the left station. Online, both buttons now change NO and NC together on a slow press. THRSe hasn't faulted all shift, operators pressing normally.
Whoever put the station back together stacked the right operator the other way round. The NC sat on the rear block, opened late in the travel, and that channel always turned up behind its own NO. The instruction was right to fault it and the operators were never slow.
Still don't get why a slow press was worse than a fast one. Thanks ronh55 and mikko.
Slow press gives the rear block longer to be late. Fast press hides it.