hi, i am building a circuit and i was wondering if i could run this by you guys.
see if this is right?
thanks

 

Your SIP is simply adding MORE current requirement to the input.

The ULN2803 has 2.3k Ohm resistors in series with each input.
If your input is 5v, that will result in roughly (5v-1.2v)/2.3k = 3.8v/2.3k = 1.652mA current.

Is that too much? If so, you need to look at a different technology.

 

so this is what i want to do?

thanks

 

Yes.
Is your PLC capable of sourcing 1.5mA at 5v?

 

yes it is, its one of the cubloc controllers.

 

You should be fine then.