Connecting output devices to S7-1200

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zane Herrell-Runner

7 months ago

Hello I just started using My Siemens S7-1200 starter Kit

I am running firmware 4.3 and the product is 6ES7 212-1BE40-OXB0

I successfully connected to my PC and TIA Portal and setup A latching program with the input simulator.

I downloaded the logic and everything seems to work great. DI.0 and D0.0 light come on and switch off correctly with DI.1

So I decided to wire up a 24V AC/DC 20ma LED Light. 2 prong

1 prong to 1L on output and the other to D0.0

But the light is not powering on. I have looked at the wiring diagrams and assumed this was correct being relay outputs. Do I need to provide power from the 24vdc? That doesn't make sense since the power supply is internal.

Any help is greatly appreciated.

Scott S Mod

7 months ago

Max has given the correct answer to your question. You will need to connect 24VDC+ to Pin 3L+ of terminal block X12 and 24COM to Pin 3M of X12, per the wiring diagrams. This is power for the digital output relays.

Then, connect DO 1 (Pin DQ a.0 on terminal block X12) to one side of the lamp and he other side to 24COM. This assumes you are using the first DO channel.

Have fun with learning how to wire the I/O and read the wiring diagrams. This is where you can actually see your program logic in action!

Max

7 months ago

Good evening, zane Herrell-Runner,
As I may understand, you are trying to wire your LED to DO of the CPU and to control it, consequently, as discrete output. So, answering your question, yes, to make it work correctly, we need to connect "+" of PS 24 VDC/VAC(probably VDC, cause you are already using PS 24 VDC to power your CPU) to 1L. Then one wire from DO you are going to use to LED and then another wire of LED to "-" of PS 24 VDC/VAC.
Generally, it is because of the fact, that some groups of contacts in Siemens modules are galvanically isolated and to use them correctly we need to make independent circuits. From my personal point of view, it is very useful feature, but we should remember, that modules are pretty different and to make everything work correctly, we should pay attention to the major scheme.