
Section 7. Measurement Instructions
Parameter
& Data Type
Enter
Mult, Offset
Constant,
Variable,
Array, or
Expression
A multiplier and offset by which to scale the raw results of the measurement. See
the measurement description for the units of the raw result; a multiplier of one and an
offset of 0 are necessary to output in the raw units. For example, the TCDiff
instruction measures a thermocouple and outputs temperature in degrees C. A
multiplier of 1.8 and an offset of 32 will convert the temperature to degrees F.
The PulseCount instruction is used to measure counts or frequency on one of
the pulse channels.
The PulseCount instruction can not be used in a Slow Sequence
scan.
NOTE
CR23X
Pi
20k
CR800
FIGURE 7.7-2. Conditioning Large Voltage Pulses
The maximum input voltage on a pulse channel is ±20 V. Refer to Figure
7.7-2 if reducing input voltage is required.
• Pulse Channels
Maximum Input Voltage: ±20 V
High Frequency Input
• Pulse Channels
Minimum Pulse Width: 1.2 microsecond
Maximum Frequency: 400 kHz
(50% Duty Cycle)
Lower Threshold: 1.5 V*
Upper Threshold: 3.5 V*
When a pulse channel is configured for high-frequency pulse, there is an
internal 100 kohm pull-up resistor to 5 V on the pulse channel. This pull-up
resistor accommodates open-collector output devices for high-frequency input.
*Larger input transitions are required at high frequencies because of the input
RC filter with 1.2 microsecond time constant. Signals up to 400 kHz will be
7-20
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