15.18 Checking Sensor Pins; Remote Core Processor With Remote Transmitter Installation - Emerson Micro Motion 3711 Configuration And Use Manual

Maintenance and Troubleshooting
To return to normal operation:
1. Reconnect the 4-wire cable between the core processor and the Model 3711.
2. Replace the core processor lid.
Note: When reassembling the meter components, be sure to grease all O-rings.
Figure 15-2 Core processor resistance test

15.18 Checking sensor pins

Problems with sensor pins can cause several alarms, including sensor failure and a variety of
out-of-range conditions. Testing the sensor pins involves testing the pin pairs and testing for shorts to
case.
15.18.1

Remote core processor with remote transmitter installation

If you have a remote core processor with remote transmitter installation (see Figure A-2):
1. Power down the Model 3711.
2. Remove the end-cap from the core processor housing (see Figure A-3).
3. Unplug the terminal blocks from the terminal board.
4. Using a digital multimeter (DMM), check the pickoff pins listed in Table 15-8 by placing the
DMM leads on the unplugged terminal blocks for each pin pair. Record the values.
Table 15-8 Pins and test terminal pairs
Pin
Drive pin
Left pickoff pin (LPO)
Right pickoff pin (RPO)
Resistance temperature detector (RTD)
Lead length compensator (LLC) (all sensors except CMF400 I.S. and T-Series)
Composite RTD (T-Series sensors only)
Fixed resistor (CMF400 I.S. sensors only)
184
40 kΩ –50 kΩ
20 kΩ – 25 kΩ
20 kΩ – 25 kΩ
Test pin pair
Colors
Brown to red
Green to white
Blue to gray
Yellow to violet
Yellow to orange
®
Micro Motion Model 3711 Gas Flow Computers
Numbers
3 — 4
5 — 6
7 — 8
1 — 2
1 — 9