1257 User Manual
Advanced SCPI Operations 7-12
EADS North America Defense
Test and Services, Inc.
©
2001
This produces a delay from the time the relay closes till the trigger
is felt. The trigger is programmed in seconds, with a resolution of 1
microsecond. This is the
resolution
and not the
accuracy
. That
means that you will receive 0.00000 (5 decimal places) when you
read it. Any delay over 10 milliseconds rounds the delay to the
nearest 10 milliseconds.
Figure 7-2, Using External Trigger In and External Trigger Out
Using Scan Lists
and External
Trigger Input
A scan list allows you to specify a list of switching commands to be
performed. Once you have defined this list, the 1257 will
automatically sequence through the scan list, executing one
command each time it detects a trigger pulse at the external trigger
input of the SYNC/TRIG connector.
Three types of commands may be entered into a scan list:
•
Close a specific relay
•
Recall a state stored in a non-volatile memory location
•
Break (stop scan list processing)
Scan Lists
The 1257 may be programmed to sequence through a list of
channels. This feature is known as a “Scan List”.
When a Scan List is used, the user defines a list of channels to
operate. Each time a trigger is received by the 1257, the presently
closed channel is opened, and the next channel on the list is
closed. This capability may be used in conjunction with a Digital
Multimeter (DMM) or other measurement device to allow a group
of measurements to be made without having to program the 1257
for each relay operation.
For example, without the Scan List feature, for
each
DMM reading,
Trigger IN
Trigger OUT
