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*OPC reports when operation is com
-
plete, via the Status Subsystem described
on page 6-14.
Rough Trigger
Subsystem
Description
The trigger subsystem is the functional
part of the CNT-8X that controls the start
and stop of measurements. This is the
function that the controller interacts with
when it controls the measurement se-
quence.
A simplified model of the CNT-8X’s trig-
ger subsystem is a state-machine with
four different states. These states are as
follows:
IDLE State
–
The counter waits for new commands. It is
not measuring
WAIT_FOR_BUS_ARM State
–
The counter is ready to receive a bus arm
-
ing signal, GET or XTRG.
WAIT_ FOR_MEASUREMENT_TO_
START State
–
The counter waits for the input signal trig
-
gering to start the measurement or block of
measurements. If the counter uses arming,
it is waiting for the specified arming event.
MEASUREMENT State
–
The counter measures. It monitors the
hardware and controls the measurement
time. If block measurement mode is used,
(ARM:COUN or TRIG:COUN8³2) the
counter stays in this state until all measure
-
ments inside the block has been made.
Different actions cause the trigger sub
-
system to change between the different
states. The transitions are shown in . The
status is reflected in status byte
:STATus:OPERation:CONDition.
How to Measure Fast
Rough Trigger Subsystem Description 7-3
State:
ID L E
O peration Condition
re g is te r s ta tu s :
256
State:
W A IT F O R B U S A R M
O peration Condition register
status: 320
State:
W A IT F O R E X T A R M a n d /o r
IN P U T T R IG
O peration Condition register
status:
288
State:
MEASURE
O peration Condition
re g is te r s ta tu s :
16
INIT
INIT:CONT ON
or
INIT:CONT OFF
O r all m easurem ent
s
com pleted
Bustrig received or
O FF (im m ediate)
All ARM and TRIG
loops com pleted
(A rm in g rece ive d o r
a rm o ff (im m e d ia te ))
and input trig
Single m easurem ent
re a dy
Figure 7-1 Trigger subsystem states.