Sensaphone SCADA 3000 Users manual - Manual (Page 259)

24-5
Chapter 24: Pulse Count Module
to digital logic signals, follow the polarity markings shown at the terminal strip. Note that if
the sensor is located far from the Pulse Count Module or if you are running cable in an electri-
cally noisy environment, you should seriously consider using shielded cable. This will shield
the signal from electrical interference, thereby preventing false readings and/or damage to the
module.
Figure 8: Module Input wiring
Adjusting the Trimpot (Filtering)
Each channel of the pulse count module has an adjustable low-pass filter. This filter is used
to prevent errors generated by the bounce from slow-moving switches. The filter cut-off fre-
quency is adjusted by turning the trimpot (as shown in Figure 9) to the appropriate position.
The trimpot range is scaled from 0 to 10. Adjust the trimpot based on the maximum pulse fre-
quency expected in your application. The table below will help you select the correct position.
Maximum
Pulse Frequency Trimpot Position
200 Hz 0
350 Hz 2 1 ⁄
2
700 Hz 5
1200 Hz 7 1 ⁄
2
10,000Hz 10
Figure 9: Trimpots, with Pot 1 set at 0, Pot 2 at 2.5, Pot 3 at 5, and Pot 4 at 10
APPLICATION: HOW THe PULSe COUNT mODULe WORKS
The two main uses for the Pulse Count Module are:
a) to measure and record flow rates. The liquid flow rate sensor operates like a pad-
dlewheel, and each rotation causes an electrical pulse.
b) to measure RPM. Industrial generator or motor activity is usually measured in
RPMs.
The SCADA 3000 Pulse Count Module splits incoming data into four channels of accumulated
pulse, and four virtual channels measuring the rate of pulses, thus generating a total of eight.
Thus you can receive two different measurements from a single input.