Tp1 - Emerson Rosemount 8600D Series Reference Manual

Section 5: Troubleshooting
January 2013
The electronics is capable of internally generating a flow signal that may be used to simulate a
sensor signal to perform electronics verification with a Handheld Communicator or AMS
interface. The simulated signal amplitude is based on the transmitter required minimum
process density. The signal being simulated can be one of several profiles – a simulated signal of
constant frequency or a simulated signal representative of a ramping flow rate. The electronics
verification procedure is described in detail in
electronics, you can input a frequency on the "TEST FREQ IN" and "GROUND" pins to simulate
flow via an external signal source such as a frequency generator. To analyze and/or troubleshoot
the electronics, an oscilloscope (set for AC coupling) and a Handheld Communicator or AMS
interface are required.
the microprocessor in the electronics.
Figure 5-2. Signal Flow
Sensor
External
Test
Frequency
Input
5.3.3

TP1

TP1 is the vortex shedding signal after it has gone through the charge amplifier and low pass filter
stages and into the input of the sigma delta A-to-D converter ASIC in the electronics. The signal
strength at this point will be in the mV to Volt range.
TP1 is easily measured with standard equipment.
Figures 5-3, 5-4, and
output to be inaccurate. Please consult the factory if the waveform you detect is not similar in
principle to these waveforms.
Figure 5-3. Clean Signals
0
3.0 V
0
72
Figure 5-2 is a block diagram of the signal as it flows from the sensor to
TP1
Charge
Amplifier/
Amplifier
Low Pass
Filter
5-5 show ideal (clean) waveforms and waveforms that may cause the
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Appendix C: Electronics
A-to-D
Converter
Internal
Digital Filter
Frequency
Generator
Vortex Signal (TP1)
Trigger
Level
Shedding
Frequency
Output
Reference Manual
00809-0100-4860, Rev BC
verification. To verify the
Microprocessor
Troubleshooting