Emerson Process Management 1500 manual Core processor resistance test

Troubleshooting

Table 11-12Enhanced core processor LED behavior, meter conditions, and remedies

LED behavior	Condition	Possible remedy
Solid green	Normal operation	No action required.
Flashing yellow	Zero in progress	If calibration is in progress, no action required. If no calibration is in
		progress, contact Micro Motion. See Section 1.8.
Solid yellow	Low severity alarm	Check alarm status.
Solid red	High severity alarm	Check alarm status.
Flashing red (80% on,	Tubes not full	If alarm A105 (slug flow) is active, see Section 11.17.
20% off)
		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.
Flashing red (50% on,	Electronics failed	Contact Micro Motion. See Section 1.8.
50% off)
Flashing red (50% on,	Sensor failed	Contact Micro Motion. See Section 1.8.
50% off, skips every
4th)
OFF	Core processor	• Verify power supply wiring to core processor. Refer to Appendix B for
	receiving less than 5	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 11.14.1, and refer to
		Appendix B for diagrams. Otherwise, contact Micro Motion (see
		Section 1.8).
		• If transmitter status LED is not lit, transmitter is not receiving power.
		Check power supply. See Section 11.14.1, and refer to Appendix B
		for diagrams. If power supply is operational, internal transmitter,
		display, or LED failure is possible. Contact Micro Motion. See
		Section 1.8.
	Core processor	Contact Micro Motion. See Section 1.8.
	internal failure

11.24.2Core processor resistance test

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 (see Figure B-3or Figure B-4).

4.Measure the resistance between core processor terminals 3 and 4 (RS-485/A and RS-485/B). See Figure 11-1.Resistance should be 40 kΩ to 50 kΩ.

5.Measure the resistance between core processor terminals 2 and 3 (VDC– and RS-485/A). Resistance should be 20 kΩ to 25 kΩ.

6.Measure the resistance between core processor terminals 2 and 4 (VDC– and RS-485/B). Resistance should be 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. Contact Micro Motion (see Section 1.8).

Compensation

Measurement Performance

Troubleshooting

Defaults

Configuration and Use Manual 109