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Document type:
Title:
User's Manual (MUT)
N1145 Quad Scaler and Preset Counter/Timer
3. Principles of operation
3.1. Sections 1 to 4
The 8-digit up-counters can operate in three distinct modes, which are:
NORMAL
GATE
GATE + CLEAR
The modes are manually selectable, for each section, by the relevant switches (see §
2.3) on the front panel. The up-counters are reset to zero, either manually (individually for
each section) by acting on the RESET pushbuttons, or electrically (common to all
sections) by means of a NIM/TTL pulse on the RESET input.
Sections 1 and 3 have two NIM/TTL high impedance GATE bridged inputs which are
internally connected; a NIM/TTL input must be terminated with a 50 Ω impedance at the
other port.
Sections 2 and 4 have one 50 Ω GATE NIM/TTL input and one CARRY NIM output. The
CARRY output generates a NIM pulse when the counter has fully cycled (transition from
max counter value to zero). This can be used to extend the counters' range by cascading
sections, as shown later.
3.2. Section 5
The fifth counter is a 7 -digit counter that can operate as a PRESETTABLE DOWN-
COUNTER or as a TIMER. Either mode is selected by the manual SOURCE SELECT
switch (labelled COUNTER/TIMER).
In COUNTER mode
In TIMER mode
In either mode, the counter must be initally preset to the desired value by acting on the
Thumb wheel switches and then by loading the datum either manually with the LOAD
pushbutton or electrically with the LOAD NIM/TTL pulse
2
Any value can be loaded except Zero, which is not recognised by the module.
NPO:
00115/01:N1145.MUTx/00
Free running. The counter is incremented by the input pulses.
The counter is incremented by input pulses only if the GATE
input is true.
Same as GATE mode, but the leading edge of the GATE input
clears the counter.
the counter is decremented by the external (NIM or TTL) input
pulses.
the counter is decremented by an internal clock, regardless the
input pulses. The frequency is selectable by acting on the
TIMER switch and can be set to 1 KHz (1 ms) or to 1 MHz
(1 µs).
Filename:
N1145_REV0.doc
Revision date:
Re vision:
05/11/2003
0
2
. At the trailing edge of the first
Number of pages:
14
Page:
9
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