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Optional Keywords
Querying Parameter
Setting
SCPI Command
Terminator
SCPI Command Basics 5-4
Command keywords enclosed in square brackets are optional. For
example, the following commands are valid and equivalent:
ROUTE:CLOSE (@5(0))
CLOSE (@5(0))
Most of the commands in SCPI have an equivalent query form.
The query is used to read the present state of the item that is set
with the command. The query is formed by adding a question mark
(?) to the end of the command keyword.
For example, the command:
ROUTE:CLOSE (@5(0))
Has an equivalent query:
ROUTE:CLOSE? (@5(0))
The command instructs the 1256 to close channel 0 on relay
module 5. The query inquires about the present open or close
state of channel 0 on relay module 5.
SCPI commands can be terminated several ways depending on
whether the GPIB or RS-232 serial interface is used.
For commands sent through the GPIB interface, a command string
sent to the 1256 must be terminated with one of the following:
1. An ASCII linefeed character (decimal 10, hex 0A, or a
character '\n').
2. The last character with the EOI signal asserted.
3. An ASCII linefeed character with the EOI signal asserted.
For commands sent through the RS-232 interface, several different
rules apply. Generally speaking, the RS-232 interface can be
accessed a number of different ways that directly impact the
termination method:
1. An ASCII linefeed character (decimal 10, hex 0A, or a
character '\n').
2. An ASCII carriage return (decimal 13, hex 0D, or a character
'\r').
3. An ASCII carriage return character followed by a linefeed
character.
1256E User Manual
Racal Instruments © 2002
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