Front Panel Operation
2-91
Semi-synchronous operation
In the Semi-synchronous Trigger Link mode, all triggering
(input and output) is controlled by a single line. When the
normally high (+5V) trigger line is pulled low (0V), a trigger
occurs on the negative-going edge. When the trigger line is
released, a trigger occurs on the positive-going edge (see
Figure 2-71). The advantage of this single line trigger is that
as long as one of the instruments in the system holds the line
low, the trigger is suppressed. In other words, the trigger
does not occur until all instruments in the system are ready.
For example, assume that a Model 6517A is connected to
two Model 7001 or 7002 Switch Systems for semi-synchro-
nous operation, as shown in Figure 2-72. All three instru-
ments are programmed to use trigger line #1. The two Model
Figure 2-71
Semi-synchronous Trigger Link specifications
Trigger on
negative-going
edge
Trigger on
positive-going
edge
+5V
0V
Pulled low by
source instrument
Released by
acceptor instruments
7001s/7002s have relay settling times of 10msec and
50msec, respectively. The Model 6517A is designated as the
trigger control source and the two Model 7001/7002 units as
trigger control acceptors.
Assume that the Model 6517A initially performs a measure-
ment. After the reading is done, the Model 6517A drives the
trigger line low. The negative-going edge triggers both Mod-
el 7001s/7002s to close a channel. While the Model 7001s/
7002s are in the process of closing a channel, they hold the
trigger line low. Ten milliseconds after switch closure, the
first Model 7001/7002 releases the trigger line. However, the
second Model 7001/7002 continues to hold the line low since
it is not finished. Fifty milliseconds after switch closure, the
second Model 7001/7002 releases the trigger line. The posi-
tive-going edge triggers the Model 6517A to make a mea-
surement and subsequently pull the trigger line back down to
close the next channels. This process continues until all
channels are scanned and measured.
Semi-synchronous Trigger Link example
This example uses the same test system (Figure 2-64) that
was used for the Asynchronous Trigger Link example #1.
However, triggering is done using the Semi-synchronous
mode. Trigger Link connections are shown in Figure 2-73.
The two instruments are configured as follows:
Line #1
7001 or 7002 Switch System
Trigger Link
Cables (2)
(8501)
Model
6517A
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
IEEE-
488
CHANNEL
READY
EXTERNAL
TRIGGER
O
U
T
I
N
C
A
R
D
90-250V
50-400Hz
40VA
MAX
LINE
RATING
2
TRIGGER LINK
DIGITAL I/O
C
A
R
D
1
MADE IN USA
7001 or 7002 Switch System
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
IEEE-
488
CHANNEL
READY
EXTERNAL
TRIGGER
O
U
T
I
N
C
A
R
D
90-250V
50-400Hz
40VA
MAX
LINE
RATING
2
TRIGGER LINK
DIGITAL I/O
C
A
R
D
1
MADE IN USA
Line #1
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
WARNING:
NO INTERNAL OPERATOR SERVICABLE PARTS,SERVICE BY QUALIFIED PERSONNEL ONLY.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
CAUTION:
FOR CONTINUED PROTECTION AGAINST FIRE HAZARD,REPLACE FUSE WITH SAME TYPE AND RATING.
INPUT
250V PEAK
!
LINE RATING
50-60HZ
50VA MAX
AC ONLY
LINE FUSE
SLOWBLOW
1/2A 90-125V
1/4A 180-250V
IEEE-488
(CHANGE IEEE ADDRESS
WITH FRONT PANEL MENU)
DIGITAL
I/O
TRIG LINK
115V
Trigger Link
Connector
Trigger
Link
IN
OUT
Trigger
Link
IN
OUT
Figure 2-72
Typical semi-synchronous mode connections
