Core Processor Resistance Test - Emerson Micro Motion 3711 Configuration And Use Manual

Maintenance and Troubleshooting
3. Check the core processor LED against the conditions described in Table 15-7.
4. To return to normal operation, replace the lid.
Note: When reassembling the meter components, be sure to grease all O-rings.
Table 15-7 Core processor LED behavior, meter conditions, and remedies
LED behavior Condition
1 flash per second (ON Normal operation
25%, OFF 75%)
1 flash per second (ON Slug flow
75%, OFF 25%)
Solid ON Zero or calibration in
progress
Core processor
receiving between 11.5
and 5 volts
3 rapid flashes, Sensor not recognized
followed by pause
Improper configuration
Broken pin between
sensor and core
processor
4 flashes per second Fault condition
OFF Core processor
receiving less than 5
volts
Core processor
internal failure
15.17.2

Core processor resistance test

To perform the core processor resistance test:
1. Remove the core processor lid.
2. Disconnect the 4-wire cable between the core processor and the Model 3711.
3. Measure the resistance between core processor terminals 3 and 4 (RS-485A and RS-485B).
See Figure 15-2. Resistance should be 40 kΩ to 50 kΩ.
4. Measure the resistance between core processor terminals 2 and 3 (VDC– and RS-485A).
Resistance should be 20 kΩ to 25 kΩ.
5. Measure the resistance between core processor terminals 2 and 4 (VDC– and RS-485B).
Resistance should be 20 kΩ to 25 kΩ.
6. If any resistance measurements are lower than specified, the core processor may not be able to
communicate with the Model 3711. Contact Micro Motion (see Section 1.8).
Configuration and Use Manual
Possible remedy
No action required.
See Section 15.12.
If calibration is in progress, no action required. If no calibration is in
progress, contact Micro Motion. See Section 1.8.
.
Verify power supply wiring See Section 15.15.1.
Check wiring between Model 3711 and sensor. See Section 15.15.2
Check sensor characterization parameters. See Section 5.5.1.
Contact Micro Motion. See Section 1.8.
Check alarm status.
.
• Verify power supply wiring
• If Model 3711 display is active, device is receiving power. Check
voltage across terminals 1 (VDC+) and 2 (VDC–) in core processor.
Normal reading is approximately 14 VDC. If reading is normal,
internal core processor failure is possible. Contact Micro Motion. If
reading is 0, internal device failure is possible. Contact Micro Motion.
If reading is less than 1 VDC, verify power supply wiring to core
processor. Wires may be switched. See Section 15.15.1.
• If Model 3711 display is not lit, device is not receiving power. Check
power supply. See Section 15.15.1. If power supply is operational,
internal device failure is possible. Contact Micro Motion. See
Section 1.8.
Contact Micro Motion. See Section 1.8.
See Section 15.15.1.
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