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Introduction to Programming - 2Suffixes and MultipliersClass Suffix Unit Unit with MultiplierAmplitude V volt MV (millivolt)Current A ampere MA (milliampere)Power W watt MW (milliwatt)Resistance OHM ohm MOHM (megohm)Slew Rate A/sR/sV/samps/secondohms/secondvolts/secondTime s second MS (millisecond)Common Multipliers1E3 K kilo1E-3 M milli1E-6 U microResponse Data TypesCharacter strings returned by query statements may take either of the following forms, depending on thelength of the returned string: Character Response Data. Permits the return of character strings. Arbitrary ASCII Response Data. Permits the return of undelimited 7-bit ASCII. This data typehas an implied message terminator. String Response Data. Returns string parameters enclosed in double quotes.SCPI Command CompletionSCPI commands sent to the electronic load are processed either sequentially or in parallel. Sequentialcommands finish execution before a subsequent command begins. Parallel commands allow othercommands to begin executing while the parallel command is still executing. Commands that affect triggeractions are among the parallel commands.The *WAI, *OPC, and *OPC? common commands provide different ways of indicating when alltransmitted commands, including any parallel ones, have completed their operations. The syntax andparameters for these commands are described in chapter 4. Some practical considerations for usingthese commands are as follows:*WAI This prevents the electronic load from processing subsequent commands until allpending operations are completed.*OPC? This places a 1 in the Output Queue when all pending operations have completed.Because it requires your program to read the returned value before executing the nextprogram statement, *OPC? can be used to cause the controller to wait for commandsto complete before proceeding with its program.*OPC This sets the OPC status bit when all pending operations have completed. Since yourprogram can read this status bit on an interrupt basis, *OPC allows subsequentcommands to be executed.NOTE: The trigger system must be in the Idle state in order for the status OPC bit to be true.Therefore, as far as triggers are concerned, OPC is false whenever the trigger system isin the Initiated state.21
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