PLC Faults caused by 1746-HSTP1

Hi all,

I need some help fixing an ongoing issue I’m having that involves the 1746-HSTP1 stepper module.

The equipment randomly shuts down due to a the PLC faulting and I’m not sure why. The 5/03 PLC shows that there is a major error halt and the error description states: “Specialty I/O module in slot 5 has generated a generic fault. The card fault bit is set (1) in the module’s status byte.” I haven’t been able to catch this in action and not sure what’s causing it.

The operators just run the machine, pushing buttons on the HMI and it happens. Silly question: Could the faults be caused by the operators hitting the buttons too fast? Could it be loose wires, lack of feedback from the motor? I have attached a snippet of the errors tab in the PLC. Maybe it can shed some light on my issue.

Thanks.

This thread talks a little bit about that specific error.

http://www.plctalk.net/qanda/showthread.php?t=64502

Part of it says to move the module to the other slot, if the error follows the module, replace it.

In general, no matter what goes wrong with the application of a specialty module it won't fault the backplane connection.

Like if a BASIC module goes into an infinite loop... that makes the BASIC runtime useless but won't crash the backplane connection.

Or if a servo module loses its feedback connection. That will make the position loop fail and the servo control function fault, but it won't crash the backplane connection.

But specialty modules have more to do across the backplane than simple I/O modules, so there's more chances for something in their backplane microcontroller or their pins to screw up.

In general if the module has been working well for years and it starts to fault, then the problem is electrical spikes, a failing backplane, or (most likely) a failing module.

Thanks for the feedback. The equipment has been running for years but i don't know exactly when the problem started happening. It usually happens when the operator runs the equipment manually. When the equipment is in auto, the PLC seldom faults. Its a nuisance and something that I want to correct.

If I do swap out the module, it looks like a direct swap and I don't need to make any configuration changes.