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Status and Events
/* Take amplitu
de measur ement */
MEASUREMENT:IMMED:VALUE
This sequence
lets you create your own wait loop rather than using the *WAI
command. The BUSY? query h elps you avoid time-outs caused by writing too
many commands to the input buffer. The controller is still tied up though, and
the repeated BUSY? query will result in bus traffic.
Using the *OPC Command
If the corresponding status registers are enabled, the *OPC command sets the
OPC bit in the Standard Event Status Register (SESR) when an operation is
complete. You achieve synchronization by using this command with either a
serial poll or service request handler.
Serial Poll Method: Enable the OPC bit in the Device Event Status Enable
Register (DESER) and the Event Status Enable Register (ESER) using the DESE
and *ESE commands.
When the operation is complete, the OPC bit in the Standard Event Status Register
(SESR) will be enabled and the Event Status Bit (ESB) in the Status Byte Register
will be
enabled.
The same command sequence using the *OPC command for synchronization with
seria
l polling looks like this:
/* Set up conditional ac quisition */
ACQU
IRE:STATE OFF
SELECT:CH1 ON
HORIZONTAL:RECORDLENGTH 1000
ACQUIRE:MODE SAMPLE
ACQUIRE:STOPAFTER SEQUENCE
/* Enab le the s tatus registers */
DE
SE 1
*ESE 1
*SRE 0
/* Acqu ire waveform data */
ACQUIRE:STATE ON
/* Set up the measurement parameters */
MEASUREMENT:IMMED:TYPE AMPLITUDE
MEASUREMENT:IMMED:SOURCE CH1
/* Wait until the acquis ition is complete before taking the
measurement.*/
*OPC
While s erial poll = 0, keep loopi ng
/* Take amplitude measurement */
MEASUREMENT:IMMED:VALUE
This technique requires less bus trafficthandidloopingonBUSY.
3-10 MSO4000 and DPO4000 Series Programmer Manual