8.4 Communication Methods
101
8
Chapter 8 RS-232C/GP-IB Interfaces
Response
Messages
When a query message is received, its syntax is checked and a response mes-
sage is generated.
The
:SYSTem:HEADer command determines whether headers are prefixed
to response messages.
Header ON
:RESISTANCE:RANGE 300.00E-3
Header OFF 300.00E-3
(the current resistance measurement range is 300 mΩ)
At power-on, Header OFF is selected.
If an error occurs when a query message is received, no response message is
generated for that query.
No header is applied to commands used only for queries, such as
:FETCh?,
:MEASure and :CALCulate:LIMit:RESistance:RESult?.
Command Syntax Command names are chosen to mnemonically represent their function, and can
be abbreviated. The full command name is called the "long form", and the abbre-
viated name is called the "short form".
The command references in this manual indicate the short form in upper-case
letters, extended to the long form in lower case letters, although the commands
are not case-sensitive in actual usage.
Response messages generated by the instrument are in long form and in upper
case letters.
Headers Headers must always be prefixed to program messages.
(1) Command Program Headers
There are three types of commands: Simple, Compound and Standard.
• Headers for Simple Commands
This header type is a sequence of letters and digits
∗
ESE 0
• Headers for Compound Commands
These headers consist of multiple simple command type headers separated by
colons ":"
:SAMPle:RATE
• Headers for Standard Commands
This header type begins with an asterisk "*",
indicating that it is a standard command defined by IEEE 488.2.
∗
RST
(2) Query Program Header
These commands are used to interrogate the instrument about the results of
operations, measured values and the current states of instrument settings.
As shown by the following examples, a query is formed by appending a question
mark "?" after a program header.
:FETCh?
:MEASure:RESistance?
FUNCTION
OK (long form)
FUNC
OK (short form)
FUNCT
Error
FUN
Error
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