Filter
Top Products
72
Reference Manual
00809-0100-4860, Rev BC
Section 5: Troubleshooting
January 2013
Troubleshooting
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 Appendix C: Electronics verification. To verify the
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. Figure 5-2 is a block diagram of the signal as it flows from the sensor to
the microprocessor in the electronics.
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 5-5 show ideal (clean) waveforms and waveforms that may cause the
output to be inaccurate. Please consult the factory if the waveform you detect is not similar in
principle to these waveforms.
Figure 5-2. Signal Flow
Figure 5-3. Clean Signals
Sensor
Charge
Amplifier
Amplifier/
Low Pass
Filter
External
Test
Frequency
Input
TP1
Digital Filter
Microprocessor
A-to-D
Converter
Internal
Frequency
Generator
Trigger
Level
Vortex Signal (TP1)
Shedding
Frequency
Output
0
3.0 V
0