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SCPI Command Terminators
A command string sent to the instrument must terminate with a <new line> (<NL>) character (ASCII
decimal 10). The IEEE-488 EOI (End-Or-Identify) message is interpreted as a <NL> character and can be
used to terminate a command string in place of a <NL> character. A <carriage return> followed by a <NL>
is also accepted. Command string termination always resets the current SCPI command path to the root
level.
For every SCPI message that includes a query and is sent to the instrument, the instru-
ment terminates the returned response with a <NL> or line-feed character (EOI). For
example, if R? is sent, the response is terminated with a <NL> after the block of data that
is returned. If a SCPI message includes multiple queries separated by semicolons (for
example "ROUTe:TERMinals?;R?"), the returned response is again terminated by a <NL>
after the response to the last query. In either case, the program must read this <NL> in
the response before another command is sent to the instrument or an error occurs.
IEEE-488.2 Common Commands
The IEEE-488.2 standard defines a set of common commands that perform functions such as reset, self-
test and status operations. Common commands always begin with an asterisk ( * ), are three characters in
length and may include one or more parameters. The command keyword is separated from the first para-
meter by a blank space. Use a semicolon ( ; ) to separate multiple commands as shown below:
*RST; *CLS; *ESE 32; *OPC?
SCPI Parameter Types
The SCPI language defines several data formats to be used in program messages and response mes-
sages.
Numeric Parameters
Commands that require numeric parameters accept all commonly used decimal representations of num-
bers including optional signs, decimal points, and scientific notation. Special values for numeric para-
meters such as MIN, MAX and DEF are also accepted. You can also send engineering unit suffixes with
numeric parameters (e.g., M, k, m or u). If a command accepts only certain specific values, the instrument
rounds the input numeric parameters to the accepted values. The following command requires a numeric
parameter for the range value:
VOLTage:DC:RANGe {<range>|MIN|MAX|DEF}
Because the SCPI parser is case-insensitive, there is some confusion over the letter "M"
(or "m"). For your convenience, the instrument interprets "mV" (or "MV") as millivolts, but
"MHZ" (or "mhz") as megahertz. Likewise "MΩ" (or "mΩ") is interpreted as megΩ. You can
use the prefix "MA" for mega. For example, "MAV" is interpreted as megavolts.
Keysight Truevolt Series Operating and Service Guide
SCPI Programming Reference
197
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