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I/O wiring basics.

I/O wiring basics.

At our College we teach both the Rockwell PLC and the Siemens PLC.  We also teach both Ladder Logic and Function Block programming.  The first course they take in PLCs uses the Siemens S7 1200 PLC and Function Block Programming.  I do this because they are also just...
Ladder Logic Programming Basics

Ladder Logic Programming Basics

The Ladder Logic programs look like this: They are made up of “RUNGS” that form what looks like a ladder. Two bars down each side and Lines between them.  They even use what look like relay symbols.  The ladder is separated into two sides.  The conditional side, where...
The Examine ON and OFF Instructions.

The Examine ON and OFF Instructions.

Over the years I have found that the hardest instructions for anyone first starting with PLC’s to learn was the Ladder Instructions of Examine ON             and Examine OFF .  When PLC’s first came out, the idea was to make them as usable as possible by...
The PLC Scan Cycle

The PLC Scan Cycle

I have seen, that over the years, this is part of PLC’s that gets left out of a lot of courses.  Too bad.  Because over those same years I have seen Scan Cycle problems cause hair loss, throwing of tools, swearing, and even the replacement of perfectly good CPUs only...
Using Status Lights to Troubleshoot.

Using Status Lights to Troubleshoot.

Troubleshooting a PLC system down to the faulty component or software issue should take no longer than 20 minutes max.  Much less, if there is an HMI and some Messaging on it.  This is because the PLC it’s self gives you so many trouble shooting tools.  The easiest...