Missing Process Voltage (UP or UP3)

What does E4-16173 mean?

The required process voltage (UP or UP3) for the I/O bus module is not present. This critical power supply issue will prevent the I/O module and any connected field devices from operating correctly, resulting in a complete loss of I/O functionality.

• Blown fuse on the process voltage supply line (e.g., F1) feeding the I/O module's UP or UP3 terminals.
• Faulty external power supply unit (e.g., 24VDC PSU) failing to provide the required UP or UP3 voltage.
• Wiring break, loose connection, or incorrect termination in the power distribution to the I/O module (e.g., terminals UP, UP3, and COM).
• Overload condition on the process voltage rail caused by a short circuit in a connected field device or sensor.
• Internal short circuit within the I/O module causing excessive current draw and tripping upstream protection.

Click steps to track your progress.

1. 1

   1. Measure the voltage at the UP and UP3 input terminals of the I/O module (relative to COM) using a multimeter.

2. 2

   2. Inspect and test all fuses (e.g., F1, F2) on the power distribution block supplying the I/O module.

3. 3

   3. Disconnect all external field devices from the I/O module and re-measure the UP/UP3 voltage.

4. 4

   4. Verify the output voltage of the external power supply unit (e.g., 24VDC PSU) feeding the UP/UP3 rail.

5. 5

   5. Check for short circuits or open circuits in the wiring between the power supply and the I/O module's terminals.