ML1200 Faults when switched to RUN without I/O

skyfox

Lifetime Supporting Member
Join Date
Nov 2006
Location
CA
Posts
276
Hello All,

I have a Micrologix 1200 on my test bench that is going in to a Major Fault due to I/O configuration not Matching. Odd thing is that I was able to Load this with just having 2 I/O cards in the configuration, but cards actually not present. PLC would Go in to run mode without Faulting. Now That I have added a 3rd card in to the configuration, Test bench PL (being only the CPU and No IO cards) goes in to a Fault.

Is there anyway to get the PLC to not Fault without actually having I/O attached?

Original Customer PLC
---------------------
ML1200 1672-L24BWA
SLOT1: 1762-IF4
SLOT2: 1762-IR4

Test Bench PLC
---------------------
ML1200 1672-L24BWA
SLOT1: None
SLOT2: None

Same program used on customer PLC Loads and runs on Test Bench PLC without a problem while having identical hardware configuration in the PLC program, but without actual
hardware connected at Slots 1 & 2.

Now when I add a 3rd card to the I/O configuration, Test Bench PLC goes in to a Fault as soon as I switch the program to run mode. (I have tried various types of Analog and Digital I/O cards in the I/O configuration and all of them fails when trying to run the program on the Bench PLC.

Why is it working with only 2 I/O cards in the configuration (but I/O not actually connected to the Test PLC), but fails when a third card is added to the I/O configuration?

Just to clarify, logic is sound i.e. Works correctly on Customer PLC with actual hardware attached at Slot #3.

Thank for any and all help and feedback.

ML1200 IO Fault.png
 
In the RSLogix 500 status registers, I don't have Logix 500 in front of me so I'm not sure where, there is a section where you inhibit (disable) those modules. Then you should be able to run the program without it faulting.
 
From a previous post...

Geospark said:
Tip of the day:
Normally, ladder logic cannot exist for I/O addresses that are not present in the defined chassis. So you cannot write the full program, verify, download and test until you have the full complement of hardware for the project.

If you want to define the chassis configuration with modules you don't yet have, you can still download the project to the base for testing without faulting on I/O configuration mismatch.

In "IO Configuration", drag over the module you want to the required slot, then double-click the module to get "Expansion General Configuration". Select "Ignore Configuration Error" at the bottom.

Once all "virtual" modules are set for this, you can fill the chassis if need be, complete the projects logic and download with no fault. You can even test I/O from the ladder logic for the "virtual" modules and the I/O Data Files will reflect the changes. You can also use the Force Files.

Don't forget to set them back when the hardware IS present"

Regards,
George

Ignore_Configuration_Error.png
 
Last edited:
Thanks to both of you.

Ignore Configuration check box did the trick. I thought I had already done it. Turned out that I hadn't done so.

All's well Now.

Thanks Again!

Cheers!
 
Geospark,

Which version of RSLogix 500 brings up the "Expansion General Configuration"?

I have ver 9.00 & when I double click on a card I get the "Advanced IO Configuration" that doesn't have the Ignore option to check. The Config & Edit G Data buttons are grayed out when offline & online.

1Capture.JPG
 
l just tried it with 500 V9 and there is the Ignore box. Have re checked and the ignore box is available in the I/O modules for the shoe box PLC. Not available for ML1000's or Rack PLC.
 
Last edited:
for the chassis-based SLC-5/xx models, you can try the IO tab under Processor Status ... the I/O Slot Enables bits are normally all set to a status of ONE ... putting a ZERO into a bit will tell the processor to ignore the status of a specific slot/module ...
 
I was going to put at the top of my quote...

(For expandable MicroLogix controllers only)

I hesitated and then didn't bother. I knew it would pose some questions!

Yes, it's a MicroLogix feature, accessible in RSLogix 500, only when using 1762 expansion modules. Although all the expandable RSLogix 500 based controllers do have a way of doing the same thing, in different ways, as Ron has kindly pointed out.

Just to complete this...

For the MicroLogix 1500, which uses 1769 expansion modules, the "Ignore configuration error" option is also available.

You can add...

4 1762 modules to the ML1100 base

6 1762 modules to the ML1200 base

7 1762 modules to the ML1400 base

16 1769 modules to the ML1500 - 8 to the base
Plus 8 more on a second chassis via expansion cable.

Note: You can only ignore the 8 1769 modules added to the ML1500 base.
Modules on a second chassis must be present if they are added or it will fault on I/O Configuration Mismatch.

Regards,
George
 
Last edited:
... putting a ZERO into a bit will tell the processor to ignore the status of a specific slot/module ...

I did this on a test rack (5/03) & noticed the next day that none of the outputs were changing; removed the enable which should have turned ALL the outputs off, but 1/2 still were on. Then I remembered about these bits, changed S:11 & S:12 back to -1 from 0 (decimal) & then all the outputs started cycling properly.

Learn something new every day, even after 30 years at this.
 

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