Cmmo-st-c5-1-diop Error: Codes [hot]

Note: Since “cmmo-st-c5-1-diop” does not match a standard commercial HVAC, chiller, or VFD model from major brands (Carrier, Trane, Daikin, Mitsubishi, York), this post treats it as a generic or niche controller (possibly a chiller module, PLC, or OEM board). I have written the post to be useful for technicians encountering an unknown or legacy error code system.

Based on technical documentation, these are the most common faults encountered: Error 01: Under-voltage (Logic) Logic supply at [X9] is below the required 24V DC ±15%. Check power supply wiring and load. Error 02: Over-voltage cmmo-st-c5-1-diop error codes

Frequently Asked Questions (FAQ)

Q1: How do I reset an error on the CMMO-ST-C5-1-DIOP manually?

A: Apply a rising edge (0V → 24V) to DIN 3 (Digital Input 3). Alternatively, power cycle the 24V logic supply (not the 48V) for 10 seconds. If the cause is gone, the error will clear. Step-by-Step Troubleshooting Flow

Ensure your safety relay is properly feeding the [X3] connector; without this, the drive will remain in a "safe" state and won't execute movements. Connect with FCT: If you're stuck, use the Festo Configuration Tool via Ethernet to read the full diagnostic memory Power cycle the CMMO-ST-C5-1-DIOP – Wait 2 minutes

Solution:

5. Using the DIOP (Digital I/O) Module

Since your model includes -DIOP, errors may relate to the logic control inputs/outputs.

Breaking Down "cmmo-st-c5-1-diop"

• Step-by-Step Troubleshooting Flow

  1. Power cycle the CMMO-ST-C5-1-DIOP – Wait 2 minutes. Many “ghost” codes clear on restart.
  2. Check all external safeties – This controller often disables outputs if any digital input (flow, freeze, high temp) is open.
  3. Inspect the I/O ribbon cable – If your unit has a separate display, reseat that flat cable. Corrosion causes phantom E-xx codes.
  4. Measure the 5V reference – Locate pins marked Vref and GND. Should be 4.85–5.15V DC. Low voltage = bad sensor or shorted wiring.
  5. Bypass test – Temporarily jumper the suspect DI (digital input) with a wire. If the error clears, replace the field device (not the board).

  Warning Codes: Displayed as - x x y -, where the dashes replace the "E" to distinguish them from critical errors. Common CMMO-ST Error Categories