Test pulse error

What does 12 mean?

An error was detected during the generation or detection of test pulses on an I/O channel. Test pulses are critical for diagnostics and ensuring the integrity of safety circuits, especially in detecting wiring faults. This fault indicates a potential wiring problem or sensor issue, compromising safety functionality.

• An external voltage source (e.g., stray 24VDC from another cable) is interfering with the I/O module's internal test pulse detection circuitry.
• High resistance or an open circuit in the input wiring (e.g., loose connection at terminal X1.1), preventing the test pulse from being correctly received by the module.
• The connected safety sensor (e.g., light curtain, E-stop button) has an incompatible internal impedance or filtering that distorts or absorbs the test pulse.
• A short circuit in the wiring or at the sensor output, which prevents the test pulse from creating the expected voltage drop/rise.
• Internal hardware malfunction within the I/O module responsible for generating or evaluating the test pulses.

Click steps to track your progress.

1. 1

   Disconnect the sensor from the affected I/O channel (e.g., terminal X1.1) and use a multimeter to verify no external voltage is present on the input terminal.

2. 2

   Perform a continuity and resistance check on the wiring from the safety sensor to the I/O module terminals to detect any open circuits or abnormal resistance values.

3. 3

   Verify the connected safety sensor is compatible with the I/O module's test pulse functionality and specified current limits (e.g., check sensor data sheet against module specifications).

4. 4

   Temporarily connect a known good, compatible resistive load or safety contact to the input channel in place of the sensor to see if the fault clears.

5. 5

   Review the I/O module's configuration parameters (e.g., Parameter S1-01 for test pulse frequency or duration) in the engineering software to ensure they are appropriate for the connected sensor.