Question on S7 200 module connection

Please look the diagram in the link.

This is the output expansion module connections for S7-200 series.

I have two doubts. For the 24 VDC output module, unlike relay output module, why do you need to connect the return of the supply to the CPU, as the function of the PLC is to merely to switch between output terminal and the common?

Another doubt is, for the 120/230 AC output module, what does the broken line connection indicate? Why there are two identical terminals 0L?


Hope anyone oblige.

Hi,

I think the 24VDC output is a transistor type output; one for (+) supply, one for (-) supply, and the others for the load.

I'm not sure of the 120/230 AC output. Does the diagram came from the S7-200 manual or module manual from SIEMENS or just some photos on the net?

Thanks for the reply.

So you mean here the supply is for the transistor rather than the load.

Yes, the AC output is from the S7-200 manual.

I hope you are familiar how a transistor works as a switch. A typical transistor switch requires 3 wires. It is the same principle applied in the 24VDC transistor output module.

Thanks, the answer strikes.