Triconex PLC - Input Point Stuck (D.I) issue


Thread Starter


How to clear the Point Input stuck message at Digital Input 3503E? From the Triconex manual, it is stated that the Digital Input needs to be serviced at least every 6 months to avoid the message.

Why is the error message happening to the digital input points? Only a few points are giving this error message and cannot be cleared.

I've been troubleshooting this by checking the shorted inst earth and termination to the particular points. No abnormalities were found. It seems ridiculous for the Triconex system to have this error message. Is this really a genuine faulty stuck message for the DigitalInput point?

Abhijit Goswami, Haldia

"Stuck On" test is one of the self diagnostics carried out in 24VAC/DC, TMR, 32 Channel, digital input module, 3503E. This test is individually performed in triplicated routes of all 32 channels of a module to detect "Stuck On" conditions where circuitry can not tell whether a point has gone to the Off state. This is a critical test requirement of a fail safe system with de-energise to trip design.
Generally an internal switch to input circuitry is closed at predetermined interval to allow a zero input (Off) to be read by the Opto-Isolators. During the test the last data is kept stored in I/O communication processor as reference for logic processing.
If the fault reappears even after reset, the fault is not due to transients and the module need replacement.

Using the same module has potential chance of input not sensing status change from "On" to "Off".

You may refer vendor manual/contact local office for further assistance.

Jot down the points which are in alarm and then measure across the input terminals of the external termination panel to verify a good signal. Also try swapping out the module with a known good spare. If the newly installed module also detects a problem, then you can be sure its a field issue