E-3
Electronics Verification
Electronics Verification
Using an External
Frequency Generator
If an external frequency source is desirable, then test points at the top
of the electronics are available (see Figure E-2).
Tools Needed
• HART-based communicator; Model 275 or AMS
• Standard sinewave generator
1. Remove the electronics compartment cover.
2. Remove the two screws and the LCD indicator if applicable.
3. Connect a HART-based Model 275 Communicator or AMS to
the loop.
4. Access the flow simulation menu on the communicator and select
“Flow Sim External”. This item is used with an External
Frequency Generator. This will effectively disconnect the Model
8800C sensor input from the charge amplifier input of the
electronics (see Figure 4-2). The simulated flow and/or the
shedding frequency values will now be accessible via the Model
275 or AMS.
5. Connect the sinewave generator to the “TEST FREQ IN” and
“GND” points as shown in Figure E-2.
6. Set the sinewave generator amplitude to 2Vpp±10%.
7. Select the desired sinewave generator frequency.
8. Verify the generator frequency against the frequency displayed on
the Model 275 or AMS.
9. Exit the Flow Simulation Mode.
10. Reconnect the LCD indicator option (if applicable) to the
electronics board by replacing and tightening the two screws.
11. Replace and tighten the electronics compartment cover.
NOTE
To manually disconnect the sensor for precautionary measures, see
Replacing the Electronics Housing on page 4-13 for details.
Figure E-2. Test Frequency Output and Chassis Ground Points
HART Comm. 1, 2, 4, 3, 2
HART Comm. 1, 2, 4, 4
8800-0000A04C
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