Error at Output 4

What does Diag 2 Flash 4 mean?

An error has occurred specifically at digital output 4. This can be caused by faulty test pulses (due to external supply or cross-circuit), high capacitive coupling from parallel cables, an actuator current outside the 20 mA to 500 mA range, or a short-circuit/voltage drop at the output. If left unresolved, output 4 may not function safely or correctly, potentially affecting the connected safety function.

• Cross-circuit fault on digital output terminal 4 (DO4) due to external voltage supply or short to another signal line.
• Excessive capacitive coupling between output cable for DO4 and adjacent high-frequency or power cables, causing phantom signals.
• Overcurrent condition on DO4 due to a short-circuited actuator or an overloaded load connected to the output.
• Internal short-circuit or component failure within the digital output module's DO4 channel.
• Faulty or inadequate test pulse monitoring on DO4, possibly due to incorrect load impedance or external interference.

Click steps to track your progress.

1. 1

   1. Disconnect the load from digital output terminal 4 (DO4). Measure voltage between DO4 and common (0V) with a multimeter to verify no spurious voltage present.

2. 2

   2. With power off, use an insulation tester (megger) to test the insulation resistance of the DO4 cable against ground and adjacent cables; resistance should exceed 1MΩ.

3. 3

   3. Disconnect DO4 cable from the load. Connect a known good resistive load (e.g., 24VDC lamp) of appropriate rating to DO4. Command DO4 on/off and verify proper operation and voltage levels (e.g., 24VDC) at the load.

4. 4

   4. Verify parameter settings for DO4 test pulse configuration (e.g., P3-18 for duration, P3-19 for frequency) are appropriate for the connected load type.

5. 5

   5. Replace the digital output module if internal diagnostic tests indicate persistent failure on DO4 even with no load and good wiring.