Core Processor Resistance Test - Emerson Micro Motion 2700 Configuration And Use Manual

Troubleshooting
Table 6-11 Enhanced core processor LED behavior, meter conditions, and remedies (continued)
LED behavior
Solid red
Flashing red (80% on,
20% off)
Flashing red (50% on,
50% off)
Flashing red (50% on,
50% off, skips every
4th)
OFF
6.13.3

Core processor resistance test

To perform the core processor resistance test:
1. Disconnect power to the transmitter and core processor.
2. Expose the core processor according to the instructions in Section 6.13.1.
3. Measure the resistance across the following terminal pairs:
• The resistance across terminals 3 and 4 (RS-485A and RS-485B) should be
40–50 kilo-ohms.
• The resistance across terminals 2 and 3 (VDC– and RS-485A) should be 20–25 kilo-ohms.
• The resistance across terminals 2 and 4 (VDC– and RS-485B) should be 20–25 kilo-ohms.
If any of the resistance measurements are lower than specified, the core processor may not be able to
communicate with a transmitter or remote host. Contact Micro Motion Customer Service.
Configuration and Use Manual
Condition Possible remedy
High severity alarm Check alarm status.
Tubes not full If alarm A105 (slug flow) is active, see Section 6.10.
If alarm 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.
Electronics failed Contact Micro Motion Customer Service.
Sensor failed Contact Micro Motion Customer Service.
Core processor • Verify power supply wiring to core processor
receiving less than 5 Appendix A for diagrams.
volts • 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.
See Section 6.9.1. Otherwise, contact Micro Motion
Customer Service.
• If transmitter status LED is not lit, transmitter is not
receiving power. Check power supply. See Section 6.9.1. If
power supply is operational, internal transmitter, display, or
LED failure is possible. Contact Micro Motion Customer
Service.
Core processor Contact Micro Motion Customer Service.
internal failure
.
Refer to
109