Siemens S7-400 PLC - how to wire

I have this old Siemens S7-400 PLC with a CP-443 comm module, and an AI, AO, DI and DO modules. I have access to TIA software
I am just starting to learn PLCs.I have 120V going into the main PS-407 module. How do I get 24V DC to the I/O cards? I do have a separate 24V PS. Do I need to wire the V+ and V- to each module? Where? What terminals?

Can anyone walk me through the steps of wiring up a simple PB switch to the DI input module, and an LED to the DO output module.

I think I can handle the software portion (TIA) portion, just need help with the hardware.


This is where product Manuals for i/o become very useful..
" Do I need to wire the V+ and V- to each module? "
Some you do- some you don't. Analogue i/o have even more variations and possile configurations.
Hi davidxyz,

the main information source for any Siemens-PLC related question is

There you'll find the manuals for the hardware. The modules are indentified by their part number (=purchase order number). It is the number with the two hyphens printed under the top mounting screw of the module, like the "443-1EX30-0XE0" on the CP443-1 Ethernet CP.

Most of the manuals can be downloaded without user account. If you want to download program examples, you might to register with Siemens and create an account. They have an excellent support, and the program examples are quite useful.
So far, I programmed the "classical" S7-300/400 plcs only with "classical" Step 7 (Simatic Manager). If I intended to do that with TIA Portal, I would search for a program example.

Attached please find a download link to a S7-400 module documentation:

Generally, the hardware I/O modules power supply is separate from the CPU power supply and the backplane bus. If something happens to the hardware I/O modules (like 230V on the binary input instead 24V) your CPU is not damaged.

Stay healthy