What you'll learn
A PLC does nothing until it has power. In a control panel that power comes from a **24 VDC power supply** mounted on the DIN rail, and it travels in a **loop**: out of the supply on the **+24 V** terminal, through the PLC, and back to the supply on **0 V**.
- Feed the +24 V strip from the power supply, and feed the 0 V strip from it too.
- Power the PLC from the two strips.
- Bond the supply's protective earth (**PE**) to the ground bar, so a fault has a safe
Lab time: ~6 minutes.
Lesson briefing
Power the PLC
A PLC does nothing until it has power. In a control panel that power comes from a 24 VDC power supply mounted on the DIN rail, and it travels in a loop: out of the supply on the +24 V terminal, through the PLC, and back to the supply on 0 V.
Two terminal strips make that loop easy to share. One strip carries +24 V and the other carries 0 V. Every slot on a strip is the same rail, so any free slot works.
Goals:
- Feed the +24 V strip from the power supply, and feed the 0 V strip from it too.
- Power the PLC from the two strips.
- Bond the supply's protective earth (PE) to the ground bar, so a fault has a safe path to ground.
You only wire the DC side. The supply's AC input is fed from the cabinet mains upstream.
Tip: use red wire for +24 V, blue for 0 V and green-yellow for protective earth. Tap one terminal, then tap the terminal it should connect to. Press Check when you think the PLC is powered.
Hints
Think of the power as a loop. Current has to leave the supply, pass through the PLC, and come back to the supply.
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This lesson uses 6 placed components on the lab canvas. Components are vendor-neutral (no proprietary trademarks); the wiring rules apply to any equivalent industrial part.
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