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Model 6517A Getting Started Manual Remote Operation 3-9

Long and short form commands

Every SCPI command has a short form, and most also have a long form. The notation used

in documentation shows the short form in upper case, with the remainder of the name,

which creates the long form, shown in lower case. There are no intermediate forms of the

command name. You must send the exact short or long form. However, you do not have to

use the mixed capitalization. The Model 6517A accepts commands in any combination of

upper and lower case. For example, all of the following are valid forms of the

SENSe1:VOLTage[:DC]:REFerence command:

sense1:voltage[:dc]:reference:state

sens1:volt[:dc]:ref:stat

SENS1:volt[:DC]:rEFErENCe:STat

Query commands

With few exceptions, every SCPI command has a corresponding query. A command sets a

control point in the instrument; a query determines the present setting of the control point.

The query is simply the command name with a “?” attached.

Some commands are actions rather than control point settings. These commands have no

query form. For example,

SENSe1:VOLTage[:DC]:REFerence:ACQuire

is an action command, not a setting, and so has no query form.

There are some queries that have no corresponding command. For example,

SENSe1:DATA? causes the instrument to return the latest reading. Of course, there is no

corresponding command to send a reading value to the instrument.

Default nodes

SCPI uses the concept of default nodes. Consider the example command tree shown

previously in Figure 3-2. What is within square brackets is not necessary to send to the

instrument, but the instrument will accept it if you send it. Consider the :UPPer

command, which sets the measurement range. To set the Model 6517A to measure

15VDC, any of the following commands works:

SENSe1:VOLTage[:DC]:RANGe:UPPer 15

SENSe:VOLTage[:DC]:RANGe:UPPer 15

SENSe1:VOLTage[:DC]:RANGe 15

VOLTage[:DC]:RANGe:UPPer 15

VOLTage[:DC]:RANGe 15

These are shown in long form, but short forms could also be used.

Keithley 6517A Getting Started Guide

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