Campbell Scientific CR5000 Measurement and Control Module - Manual (Page 150)

Section 7. Measurement Instructions
7-24
CR23X
Pi
20k
FIGURE 7.8-1. Conditioning Large Voltage Pulses
The maximum input voltage on a pulse channel is ±20 V. Refer to Figure
7.8-1 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
counted if centered around +2.5 V with deviations
≥ ± 2.5 V for ≥ 1.2
microseconds.
Low Level AC (Pulse Channels Only)
Input Hysteresis: 15 mV
Maximum Input Voltage: 20 V peak-to-peak
Input Voltage and Frequency Range
(16 bit counter required above 2.56 kHz)
20 mV
1.0 Hz to 1 kHz
200 mV 0.5 Hz to 10 kHz
1000 mV 0.3 Hz to 16 kHz
CR5000