Keithley 2750, Руководство пользователя

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Model 2750 Multimeter/Switch System User’s Manual Triggering 8-15
Trigger model operation
Once the instrument is taken out of idle, operation proceeds through the trigger model
down to the device action. In general, the device action includes a measurement and, when
scanning, closes the next channel.
Control Source — As shown in Figure 8-10 , a control source is used to hold up operation
until the programmed event occurs. The control source options are as follows:
• IMMediate — Event detection is immediately satisfied allowing operation to
continue.
• MANual — Event detection is satisfied by pressing the TRIG key. The Model 2750
must be in LOCAL mode for it to respond to the TRIG key. Press the LOCAL key
or send GTL over the bus to remove the instrument from the remote mode.
• TIMer — With the timer source enabled (selected), event detection is immediately
satisfied. On the initial pass through the loop, the Timer Bypass is enabled allowing
operation to bypass the Timer and continue on to the Delay block.
On each subsequent pass through the loop, the Timer Bypass is disabled. Operation is then
delayed by the Timer or the Delay. If the user-set Timer interval is larger than the user-set
Delay, the Timer will control the length of the delay. Otherwise, the length of the delay is
controlled by the user-set Delay period.
The Timer interval can be set from 0 to 999999.999 seconds. The timer source is only
available during scan operation. The timer resets to its initial state when the instrument
goes into the normal mode of operation or into the idle state.
• EXTernal — Event detection is satisfied when an input trigger via the TRIG LINK
connector is received by the Model 2750.
• BUS — Event detection is satisfied when a bus trigger (GET or *TRG) is received
by the Model 2750.
Delay and Device Action — These blocks of the trigger model operate the same for both
front panel and GPIB operation. See the front panel “Trigger model,” page 8-2 , for operat-
ing information on these trigger model blocks.
Counters — Programmable counters are used to repeat operations within the trigger
model. For example, if performing a 10-channel scan, the sample counter would be set to
10. Operation will continue until all 10 channels are scanned and measured. If you wanted
to repeat the scan three times, you would set the trigger counter to three.
For a sample count value >1, the sample readings will automatically be stored in the
buffer. For example, with sample count set to 5, the five measured readings will be stored
in the buffer. If the trigger model is configured to repeat the sample readings (i.e. trigger
count = 2), those five new readings will overwrite the original five readings in the buffer.
Output Trigger — The Model 2750 will send one or more output triggers. The output
trigger is applied to the Trigger Link connector on the rear panel. It can be used to trigger
an external instrument to perform an operation.
2750-900-01.book Page 15 Wednesday, August 3, 2011 7:56 AM