Agilent Technologies 54621A Programmer's Manual page 12

Introduction to Programming
Program Message Syntax
Header Types
There are three types of headers:
• Simple Command headers
• Compound Command headers
• Common Command headers
Simple Command Header Simple command headers contain a single
mnemonic. AUTOSCALE and DIGITIZE are examples of simple command
headers typically used in this instrument. The syntax is:
<program mnemonic><terminator>
Simple command headers must occur at the beginning of a program message;
if not, they must be preceded by a colon.
When program data must be included with the simple command header (for
example, :DIGITIZE CHANNEL1), white space is added to separate the data
from the header. The syntax is:
<program mnemonic><separator><program data><terminator>
Compound Command Header Compound command headers are a
combination of two program mnemonics. The first mnemonic selects the
subsystem, and the second mnemonic selects the function within that
subsystem. The mnemonics within the compound message are separated by
colons. For example:
To execute a single function within a subsystem:
:<subsystem>:<function><separator>
<program data><terminator>
(For example :CHANNEL1:BWLIMIT ON)
Common Command Header Common command headers control IEEE
488.2 functions within the instrument (such as clear status). Their syntax is:
*<command header><terminator>
No space or separator is allowed between the asterisk (*) and the command
header. *CLS is an example of a common command header.
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