[?]: Siemens plcs Ac/DC/AC or AC/AC/AC

[Jbeard]

I'm new to the old world.
I work as an HVAC tech in a small school system that have around 30 new air handlers with run on Siemens plcs.
Most of them are s7-200's and the rest are s7-1200's.
I've noticed on the s7-200's the cpu numbers are different as are the AC/dc/ac on the data .
I know that each cpu number allows the PLC to have different inputs and outputs.
What about the part Ac/DC/AC or AC/AC/AC.
On some of the inputs on the PLC they say 24vdc.
Do some of the plc's have only dc inputs , others have only ac inputs and some have both ac/dc inputs?

[Info]

https://support.industry.siemens.com/cs ... /109744167
Catalog ST 70: Products for Totally Integrated Automation-SIMATIC

SIMATIC S7 S7-1200 Programmable controller
https://support.industry.siemens.com/cs ... /109772940