Emerson Series 3000 MVD Manuel D’Utilisation

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To perform the core processor resistance test:

1. Power down the transmitter.

2. Remove the core processor lid. 

3. Disconnect the 4-wire cable between the core processor and the transmitter.

4. Measure the resistance between core processor terminals 3 and 4 (RS-485/A and RS-485/B). 

See Figure 22-6. Resistance should be 40 k

Ω to 50 kΩ.

5. Measure the resistance between core processor terminals 2 and 3 (VDC– and RS-485/A). 

Resistance should be 20 k

Ω to 25 kΩ.

6. Measure the resistance between core processor terminals 2 and 4 (VDC– and RS-485/B). 

Resistance should be 20 k

Ω to 25 kΩ.

7. If any resistance measurements are lower than specified, the core processor may not be able to 

communicate with a transmitter or a remote host. Contact Micro Motion customer service.

8. To return to normal operation:

a.

Reconnect the 4-wire cable between the core processor and the transmitter.

b.

Replace the core processor lid.

Flashing red (50% on, 
50% off, skips every 
4th)

Sensor failed

Contact Micro Motion.

OFF

Core processor 
receiving less than 5 
volts

• Verify power supply wiring to core processor

.

• If transmitter display is lit, transmitter is receiving power. Check 

voltage across terminals 1 (VDC+) and 2 (VDC–) in core processor. 
If reading is less than 1 VDC, verify power supply wiring to core 
processor. Wires may be switched. See Section 22.11. Otherwise, 
contact Micro Motion.

• If transmitter display is not lit, transmitter is not receiving power. 

Check power supply. See Section 22.11. If power supply is 
operational, internal transmitter, display, or LED failure is possible. 
Contact Micro Motion.

Core processor 
internal failure

Contact Micro Motion.

Enhanced core processor LED behavior, flowmeter conditions, and remedies continued