Configuration and Use Manual
MMI-20019053
Troubleshooting
October 2022
Table 12-2: Enhanced core processor LED states
LED state
Solid green
Flashing yellow
Solid yellow
Solid red
Flashing red (80% on, 20% off)
Flashing red (50% on, 50% off)
Flashing red (50% on, 50% off, skips every 4th)
OFF
Description
Normal operation
Zero in progress
Low-severity alert
High-severity alert
Tubes not full
Electronics failed
Sensor failed
Core processor receiving less than 5 volts
Core processor internal failure
Recommended action
No action required.
No action required.
Check alert status.
Check alert status.
• If alert A105 (slug flow) is active, refer to the recommended actions for that alert.
• If alert A033 (tubes not full) is active, verify process. Check for air in the flow tubes, tubes not filled, foreign material in tubes, or coating in tubes.
The meter requires factory service.
The meter requires factory service.
• Verify power supply wiring to core processor.
• If transmitter status LED 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.
• If transmitter status LED is not lit, transmitter is not receiving power. Check power supply. If power supply is operational, internal transmitter, display, or LED failure is possible – the meter may require factory service.
The meter requires factory service.
12.4 Perform a 700 core processor resistance test
Note
You can perform a resistance test only on a 700 core processor.
Procedure
1. Power down the transmitter.
2. If you have a 4-wire remote installation or a remote core processor with remote transmitter installation, remove the core processor lid.
3. If you have an integral installation: a) Loosen the four cap screws that fasten the transmitter to the base.
Configuration and Use Manual 169
Troubleshooting
October 2022
Configuration and Use Manual
MMI-20019053
A. Transmitter
B. Transition ring
C. 4 x cap screws (4 mm)
D. Base
E. Core processor b) Rotate the transmitter counter-clockwise so that the cap screws are in the unlocked position.
c) Gently lift the transmitter straight up, disengaging it from the cap screws.
4. If you have a 9-wire remote installation: a) Remove the end-cap.
170 Micro Motion 2700 Transmitters with Configurable Input/Outputs
Configuration and Use Manual
MMI-20019053
Figure 12-3: 9-wire remote installation components
Troubleshooting
October 2022
A. Transmitter
B. Core processor
C. 4 x cap screws (4 mm)
D. End-cap b) Inside the core processor housing, loosen the three screws that hold the core processor mounting plate in place.
Do not remove the screws.
c) Rotate the mounting plate so that the screws are in the unlocked position.
d) Holding the tab on the mounting plate, slowly lower the mounting plate so that the top of the core processor is visible.
5. At the core processor, disconnect the 4-wire cable between the core processor and the transmitter.
6. Measure the resistance between core processor terminal pairs 3–4, 2–3, and 2–4.
Terminal pair
3–4
2–3
2–4
Function
RS-485/A and RS-485/B
VDC– and RS-485/A
VDC– and RS-485/B
Expected resistance
40 kΩ to 50 kΩ
20 kΩ to 25 kΩ
20 kΩ 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. The meter may need factory service.
Postrequisites
To return to normal operation:
• For a 4-wire remote installation or a remote core processor with remote transmitter installation:
Configuration and Use Manual 171
