1257 User Manual
EADS North America Defense
Advanced SCPI Operations 7-7
Test and Services, Inc.
©
2001
Using External
Triggering
You may provide an
External Trigger In
signal to control when the
1257 closes or opens relays. Also, the 1257 can provide an
External Trigger Out
signal to tell your equipment when the relays
have settled after opening or closing.
These signals connect to the
External Trigger In
and
External
Trigger Out
connectors on the 1257 rear panel. Refer to
Figure 7-
1, Using External Trigger In and External Trigger Out
for
connector location and signal information.
Selecting the
Trigger Source
The TRIGGER:SOURCE command selects which source is used
to trigger the scan list. Each time a trigger is received from the
selected trigger source, the 1257 advances to the next element on
the scan list.
The syntax for the TRIGGER:SOURCE command is:
:TRIGger
[ :SEQuence ]
:SOURce { BUS | HOLD |
IMMediate
|
EXT
}
The possible trigger sources are:
BUS
The GPIB bus trigger, or the “*TRG” command,
advances to the next scan list element.
HOLD
Triggers are ignored, and the scan list will not
advance.
IMMediate
The scan list, once initiated, advances as fast as
possible after considering the relay settling time,
trigger input delay, and trigger output delay. The
Scan List operation is initiated by sending an
INIT:IMMEDIATE command (or
INIT:CONTINUOUS command).
EXT
This selects the 1257 external trigger input line.
Each time a low-going pulse is received on the
line, the scan list advances to the next element.
After power-up, and after a *RST command, the trigger source is
set to IMMEDIATE.
The present trigger source may be queried using the
TRIGGER:SOURCE? query. The reply to this query will be one of
the following:
Summary of Contents for 1257
Page 6: ......
