Enhanced core processor LED states (continued)Table 10-9:
LED state Description Recommended action
OFF Core processor receiving less
than 5 volts
• Verify power supply wiring to core processor.
• If transmitter status LED is lit, transmitter is re-
ceiving 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 switch-
ed.
• If transmitter status LED is not lit, transmitter
is not receiving power. Check power supply. If
power supply is operational, internal transmit-
ter, display, or LED failure is possible – the me-
ter may require factory service.
Core processor internal failure The meter requires factory service.
10.29 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. Remove the core processor lid.
3. At the core processor, disconnect the 4-wire cable between the core processor and
the transmitter.
4. Measure the resistance between core processor terminal pairs 3–4, 2–3, and 2–4.
Terminal pair
Function Expected resistance
3–4 RS-485/A and RS-485/B 40 kΩ to 50 kΩ
2–3 VDC– and RS-485/A 20 kΩ to 25 kΩ
2–4 VDC– and RS-485/B 20 kΩ to 25 kΩ
5. 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:
1. Reconnect the 4-wire cable between the core processor and the transmitter.
Troubleshooting
Configuration and Use Manual 153
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