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
A one button start and a one button stop written as separate rungs both end in OTE Motor, and the second one wins every scan, which is why the panel lamp flickers at scan rate and the contactor never pulls in. Two things fix it: an ONS or OSR so the press lasts one scan, … Read more
Store a ControlLogix project to a 1784-SD2 card, pick the Load Image setting you need, and what an upload or a card restore will not give back at 3am.
Find every instruction that writes a tag in Studio 5000, tell a write from a read, and work out why an output with two writers flickers on a 1756-OB16D.
A CTU on the end-of-line eye of a takeaway running 0.500 m/s read 12,480 at the end of a shift in which the palletiser stacked 12,116 cartons, and it had been drifting the same way, 2.6% to 3.4% high, for three weeks. Counting cartons was one contact and a counter, and there was nothing wrong … Read more
Bit 0 of the PowerFlex 525 logic command word is Normal Stop, and it has to be sitting at 0 before bit 1 will ever start the drive. That footnote under the table in Appendix D of 520COM-UM001 is behind most of the drives that show a green connection in the I/O tree and still … Read more
Create a new Studio 5000 Logix Designer project the right way: pick the controller, match the firmware revision, add I/O, write the first rung, download and go online.
The first program almost everybody writes is a motor start and stop with a seal-in. It works on the bench. Wired into a real panel, the same logic can leave a motor running with the stop button pressed and a broken wire nobody can see. That gap between working and correct is what these exercises … Read more
XIC and XIO instructions are one of the most used basic instructions in plc ladder programming. It is in the category of bit instruction and bit instructions can be used in input and output tags. If you have a digital input, we can define and use these inputs in the PLC using the XIC instruction … Read more