Sources; Overnm Conditions - Keithley 708 Instruction Manual

Operation
4.8.1 Sources
The programmed trigger source provides the stimulus to in-
crement to the next stored setup. Possible trigger sources in-
clude:
. External trigger pulse -An appropriate pulse, applied
to the EXTERNAL TRIGGER INPUT jack on the rear
panel, provides the trigger stimulus. The power-up dc-
fault is set for external triggering.
. IEEE command triggers - IEEE-488 GET, X, or ?&Ilk
commands provide the stimulus when the appropriate
source is selected.
Use the T - trigger command to sclcct the trigger source
(.paragraph 5.9.19).
4.8.2 Overrun conditions
Once the instrument is triggered, it begins transferring relay
setup data from mainfiamc memory to the cards. If a second
trigger is received while the unit is still transferring data, a
trigger overrun condition will occur. In this case, the second
tngger 1s not processed, and the unit's ERR LED illuminates.
USC the Ul -error status command (paragraph 5.9.20) to
retrieve the cause of the error.
After the time required for transferring relay data has
clapscd, the Model 708 is able to process another trigger. If
a trigger is received before the programmed setting time has
elapsed, a not settled error will result. Use the UI - error
status command (paragraph 59.20) to retricvc the cause of
the error.
Figure 4.13 shows an example setup change and a timing di-
agram of the READY (for trigger) pulse and a high true MA-
TRIX READY pulse when the Model 708 is processing the
trigger. The status of thcsc signals is available in the serial
poll byte (see Section S). This timing is for setups with no
make/break or break/make rows.
When either make/break or break/make operation is selcct-
cd, the Model 708 switches through an intcrmcdiate setup to
ensure proper relay operation. If only m&e/break rows arc
sclccted, the Model 70X performs the following steps:
I. Closes crosspoints in make/break rows yielding an in-
tcrmediate setup.
2. Opens crosspoints in make/break rows and opens/closes
crosspoints in don't care rows yielding the desired sct-
UP.
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