GuardLogix, S7-1500F and the PL/SIL basics: safety inputs, muting, reset logic and how a safety task differs from the standard one.
JMP, LBL and MCR on a ControlLogix: Skipping Rungs, and Why MCR Is Not a Stop Rung 14 of a filling machine carries OTL Glue_Pot_On and it sits between two MCR instructions. Open the guard, the zone goes false, every OTE inside it clears to 0 — and the glue pot stays hot, because a … Read more
Safety Feedback on a Kinetix 5700: What SFX and the Safe Speed Functions Need From the Encoder A VPL-B0631T-W gives 512 cycles per motor revolution and a VPC-Bxxxx-Q gives 4096. Put the wrong one of those two numbers into the Motion Safety instance and the drive catches you: the DSL diagnostics compare the configured resolution … Read more
The 1756-OBV8S Safety Output Card: What a Pulse Test Does to a Contactor Point 3 of a 1756-OBV8S flashes red while its output is off, and the contactor it drives is behaving perfectly. That is no-load detection, and it is telling you the truth: something between OUT3-P and the coil has come apart. The detection … Read more
The 1756-IB16S Safety Input Card: Dual Channel, Test Pulses and What OSSD Means Channels 0 and 8 look like the obvious pair for a dual-channel gate switch on a 1756-IB16S. They are directly opposite each other on the terminal block and the wiring is tidy. They are also the one pair the module will not … Read more
Hardwired or Networked Safe Torque Off on a Kinetix 5700: What Each One Needs The drive is in the GuardLogix I/O tree, the safety connection shows as running, SO.SafeTorqueOff is high, and the axis still refuses to enable. Read the STO fault type over an explicit message and it comes back 104: hardwired input in … Read more
Safe Torque Off on a Kinetix 5700: Wiring the STO Connector, and What It Does Not Do One contact of the gate switch opens a few hundred milliseconds before the other, and a second later a 2198-D032-ERS4 posts GuardStopInputFault. The axis will not come back with a normal fault reset. Both safety inputs have to … Read more
A 20-750-S seated in port 4 of a PowerFlex 755, SP and SE landed on separate contacts of a 440R-D22R2, twenty-four volts measured on both pairs, and the drive faults the moment the contactor closes. The SAFETY enable jumper is still on the main control board, where it ships from the factory, and the manual … Read more
Four guard doors on a packing cell, a Trojan T15 tongue switch on each, 440K-T11390, all four pairs of contacts daisy-chained into one 440R-D22R2 relay, and the calculation for that stop function will not go past PL c. Every switch in the chain has its two direct-opening N.C. contacts, the wiring matches the drawing, and … Read more
Inputs I0 and I1 on a 1791ES-IB8XOBV4 went solid red one afternoon with the guard closed, and the DCS instruction in the GuardLogix 5580 behind them has held Input Status false ever since. The guard switch on the infeed has two NC contacts in one four-core cable, the cable was crushed where it enters the … Read more
K1 is a 110 V AC contactor on a saw, its coil is switched by a solid-state relay, the SSR is driven from output pair 0 of a 1791ES-IB8XOBV4, and every 600 ms the contactor makes a small tick you can hear from the door of the panel. The scope on O0+ shows why: the … Read more
The guard on the case packer closed at 14:07 and the infeed conveyor started on its own, with the blue reset button 4 m away and nobody within reach of it. The DCS instruction on that gate was configured Restart Type Manual, exactly as the drawing said, and the machine still restarted, because the button … Read more
K1 and K2 are 100S-C09 safety contactors in series on a 4 kW conveyor motor, the CROUT that drives them holds Fault Code 16#5003 – both feedbacks ON with the outputs off – through every press of the reset button, and the suggestion at 06:10 was to raise the Feedback Reaction Time from 100 ms … Read more