Model SR715 Model SR720 LCR Meters

REMOTE PROGRAMMINGSimilarly, the SR715/720 has a 256 characteroutput buffer to store output until the hostcomputer is ready to receive it. If the output bufferfills up it is cleared and an error reported. TheGPIB output buffer may be cleared by using theDevice Clear universal command.The present value of a particular parameter maybe determined by querying the SR715/720 for itsvalue. A query is formed by appending a questionmark "?" to the command mnemonic and omittingthe desired parameter from the command. Ifmultiple queries are sent on one command line(separated by semicolons, of course) the answerswill be returned in a single response line with theindividual responses separated by semicolons.The default response terminator that theSR715/720 sends with any answer to a query iscarriage return-linefeed on RS232 andlinefeed plus EOI on GPIB, except for binaryanswers which are terminated by a single onboth interfaces. All commands return integerresults except as noted in individual commanddescriptions.Examples of Command FormatsFREQ 2 Sets the drive frequencyto 1000 Hz ( 1 parameter).FREQ? Queries the drivefrequency (query of 1parameter command ).BLIM 0,3,1000 Sets the upper limit of bin3 to 1000W (3parameters).BLIM? 0,3Queries the upper limit ofbin 3 (query of 3parameter command).*IDN? Queries the deviceidentification (query, noparameters).*TRG FREQ 1 ;FREQ? Triggers a measurement(no parameters).Sets frequency to 120Hz(1) then queries thefrequency.PROGRAMMING ERRORSThe SR715/720 reports two types of errors thatmay occur during command execution: commanderrors and execution errors. Command errors areerrors in the command syntax. For example,unrecognized commands, illegal queries, lack ofterminators, and non-numeric arguments areexamples of command errors. Execution errorsare errors that occur during the execution ofsyntactically correct commands. For example, outof range parameters and commands that areillegal for a particular mode of operation areclassified as execution errors.NO COMMAND BITThe NO COMMAND bit is a bit in the serial pollregister that indicates that there no commandswaiting to be executed in the input queue. This bitis reset when a complete command is received inthe input queue and is set when all of thecommands in the queue have been executed. Thisbit is useful in determining when all of thecommands sent to the SR715/720 have beenexecuted. This is convenient because somecommands, such as taking a measurement, orautocalibration, take a long time to execute andthere is no other way of determining when they aredone. The NO COMMAND bit may be read whilecommands are being executed by doing a GPIBserial poll. There is no way to read this bit overRS232. Note that using the *STB? query to readthis bit will always return the value 0 because it willalways return an answer while a command isexecuting- the *STB? command itself!4-2