74 Chapter 6
Reading Out Measured Result
Reading Out Measured Result
Trigger input timing when using :READ? command
You must input a trigger after execution of the :READ? command. Therefore, if you use
different controllers for outputting the trigger and executing the :READ? command, you
need to find out whether the :READ? command has been executed from the controller for
outputting the trigger in order to prepare the proper timing for trigger output (to trigger the
instrument after execution of the :READ? command).
You can obtain this information from the /READY_FOR_TRIG signal of the handler
interface as shown in Figure 6-5.
Figure 6-5 Behavior of /READY_FOR_TRIG signal at execution of :READ? command
If the :READ? command is executed when the trigger system is in the idle state, the
/READY_FOR_TRIG signal of the handler interface changes from HIGH to LOW after
completion of the internal processing following the reception of the command as shown in
Figure 6-5.
If the trigger system continuous startup is ON, the /READY_FOR_TRIG signal changes
from HIGH to LOW (the trigger system transitions to the trigger wait state instead of the
idle state) after the completion of measurement and display update as shown in Figure 6-5.
As a result, it is not possible to determine whether the :READ? command has actually
been executed. Therefore, you need to turn OFF the trigger system continuous startup
(execute the :INIT:CONT command on page 183 specifying OFF) in advance.
NOTE In Figure 6-5, the :READ? command is executed after display is updated. In practice, you
may execute the :READ? command before or during display update provided that data
output has finished (after completion of the query of the previous :READ? command).
However, the internal processing is started after the completion of display update.
The 4288A normally updates display after data output as shown in Figure 6-5. However, if
readout of data stagnates due to the external controller, the 4288A may update display
before data output.
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