Backplane Current

I have not come across this earlier...i dont know why, but... why do the PLC manufacturers give 2 ratings for the Backplane current load for their processor or I/O modules - one @5 V and another @ 24 V.??? I frankly havent come across others but AB surely do that!!!!

Many PLC's and other electrical items use 2,3,4 or more voltage levels. PLC's ussaly use the +5 V for logic and transistor type outputs. the +12 or 24V power supply is for relay outputs and sometimes when you need a bigger voltage swing,Analog outputs and for Analog input reference sources.

So sometimes yopu may load down one supply and have lots of power free on the other. It depends on your card type population