MicroLogix 1500

Discal

Member
Join Date
Aug 2010
Location
Florida
Posts
34
There is a good possibility that I have done something dumb, but I have decided to subject myself to the ridicule anyhow.
I am running a MicroLogix 1500LRP Series C processor, installed in a 24AWA base. There are also two external cards, one each 1769-IF4 and 1769-OF2. This unit is on a test stand; takes some abuse. Recently when I powered it up I received the following fault:
The controller cannot communicate with an expansion I/O module. Exact module cannot be determined.
I changed the module(s) and received the same error. Then I changed the base and received the same error. Lastly I changed the processor and received the same error. When I try to open a new project and tell the system to “Read IO Config” the response I receive is:
Could not read IO config for slot 1
It will not allow me to manually enter the external cards either. If however, I open a new file and tell it to go online; without adding the external cards, it will fail and then show me the cards. So I know that it is actually seeing them.
I am running 8.4 on a 64bit win7 Toughbook
P.S. If I remove the cards the base functions normally.
 
Do you have the analog cards setup for internal bus power or external. If you have it setup for external, you will problably receive this fault, especially if you are turning on the power supply at the same time as the processor. It is because of the fact that the processor looks for those cards immediately and the 24VDC has not stabilized by then. Try switching to internal bus on the cards and it should go waya.

David
 
I have had this trouble with some analogs in 2 diferent Micrologix 1500. We have had this error a few times on two different machines. A couple of times it was resolved by re-seating all the connections. Sometimes, the error also "took out" the PLC program. We installed a memory module and set the load on error bit to take care of that.

So, it is probably not anything you are missing. To be sure, it would be wise to tell us what versions of RSLogix500 and RSLinx you are using, along with revisions of the hardware, just in case their is some issue that is documented at ab.com
 
We are running RS 500 8.4 on a 64bit win7 laptop. we are also running RSLinx Lite 2.57.

I am begining to think I have a bad card that has knocked out both bases. Re-reading my original post I have a couple of items backwards. I originally replaced the base 1st, thinking it was bad then replaced the cards.

Would a faulty card have taken out two bases. at this point I think that might be most likely.
 

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