SLC5/04 Fault when adding additional I/O Cards

I have (2) 1746 racks with a SLC5/04 and (8) I/O cards in each. When I attempt to add additional cards I get a fault and cannot see the 2nd rack of cards. I get this fault weather I add the cards to the 1st or 2nd rack. Any Ideas out there?

What size Racks and Power Supplies are you using?
Are we talking about one SLC5/04 with an Expansion Rack, or two SLC5/04 Systems?
What I/O Modules are you adding, to which rack, and which slot?
Did you do an Offline "Read I/O Config after you installed the modules?
Have you done a calculation to see if the Power Supply has enough capacity for the added cards?

Stu......

Your PLC continually checks to see what I/O is connected to it, then looks at the program to see what the program says is connected, and if they disagree it causes a fault.
Now if you go to I/O configuration in RSLogix 500, you will see what the program says is connected .
There are various ways to add extra I/O, all you have to do is get both to agree before putting PLC into run mode.

If you are doing the RSLogix 500 software configuration correctly, then you could have an overloaded power supply or one or more damaged I/O modules.

I shouldn't overlook this: remember that the SLC does not allow you to add or remove modules with the chassis powered up. That will fault the controller for certain !

When you have an I/O related major fault, there will be a code in the "Errors" tab of the Processor Status showing the value and description of the fault stored in the fault register. This will show you which module the SLC controller considers to have generated the fault.

If you got the 5/04 without the expension and later add in an expansion rack, then the power supply unit has to be upgraded. Seems more of a power shortage than a case of faulty cards to me

He needed a second power supply not an upgrade. Every chassis requires it's own power supply. It sounds like he has the additional power supply but he could still be overloaded.

OG

he might need to upgrade both power supplies as he says this happens reguardless if he puts the new cards on the first or second rack - so it would seem to indicate both PS's are near their max capacity