932512A / 0114
ORTEC
®
EASY-NIM
™
928 Suite
33
4.2.
COUNTER/TIMER/RATE METER (ALL MODULES EXCEPT 928-MCB)
Maximum Counting Rate
200 MHz.
Number of Counters
4 (928 and 928-COUNT-4) or 2 (928-COUNT-2).
Number of Timers
2 (928 and 928-COUNT-4) or 1 (928-COUNT-2)
Count Capacity
32 bits.
Pulse Pair Resolution
7 ns.
4.2.1.
Inputs and Outputs
Counter Input 1, 2, 3, 4
Fast analog signal input accepts analog or digital pulses up to ±5 V in amplitude on a front-
panel BNC connector. Pulses are counted as they cross the discriminator threshold. Computer selection of triggering
on either positive or negative slope. Threshold is computer adjustable from –1.6 V to +3 V in steps of 1.5 mV
(minimum pulse 30 mV). Computer selection of either 50 Ω or 1000 Ω input impedance, dc-coupled. Minimum input
pulse width is 3.5 ns at the discriminator threshold. Maximum counting rate is 200 MHz.
Input 1, 2, 3, 4, 5, 6
Front-panel BNC inputs accept any TTL input signal.
Output 1, 2
Rear-panel BNC outputs act as general purpose TTL outputs. Low is indicated by <0.4 V. High is indicated
by >+2.4 V. The outputs can drive 50 Ω. The outputs can be configured under software control to one of the following
functions:
●
Timer Interval Output
High when the counting interval is active.
●
Logic Level
Set high or low from software.
●
Counter Overflow n
“Pulse” option: 1 μs wide pulse with rising edge synchronized to the rollover of a selected counter
(n = 1, 2, 3 or 4).
“Level” option: On overflow, output remains high until manually reset.
●
Timer Overflow n
“Pulse” option: 100 ns wide pulse with rising edge synchronized to the rollover of a selected timer
(n = 1 or 2).
“Level” option: On overflow, output remains high until manually reset.
●
CRM Alarm n
Set high when count rate alarm is triggered (n = 1, 2, 3 or 4).
●
Software Control
Hardware command
SET_OUTPUT n,x
where n is the output and x is 0 or 1.
4.2.2.
Counter/Timer Software Control
Each of the counters has the following inputs and outputs.
●
Counter Input
Can be used simply as a pulse counter, or can be configured to count one of the following:
Any one of the counter input signals listed for the corresponding front-panel input.
The overflow output of any other counter or timer.
