Traversal Of The Command Tree; Execution Order - Chroma 61601 User Manual

Program Message Terminator (<PMT>):
A program message terminator represents the end of a program message. Three permitted
terminators are:
(1) <END>: end or identify (EOI)
(2) <NL>: new line which is a single ASCII-encoded byte 0A (10 decimals).
(3) <NL> <END>: new line with EOI.
Note The response message is terminated by <NL> <END> for GPIB, and <NL> for
RS-232C.
Headers
VOLT : AMPL
Head Separator

7.4 Traversal of the Command Tree

Multiple program message unit elements can be sent in a program message. The first
command is always referred to the root node. Subsequent commands are referred to the
same tree level as the previous command in a program message. A colon preceding a
program message unit changes the header path to the root level.
Example:
OUTPut : PROTection : CLEar
: OUTPut : PROTection : CLEar
OUTPut : PROTection : CLEar; : VOLT : AC 100

7.5 Execution Order

The AC source executes program messages by the order received. Program message units
except coupled commands are executed in order of reception. The execution of coupled
commands is deferred until program message terminator is received. A coupled command
sets parameters which are affected by the setting of other commands. Problems may arise,
because the prior state of the AC source will affect the response of a coupled parameter to its
programming.
For example, assume that the current output voltage range is LOW, a new state is desired
with output voltage range HIGH, and amplify 220 Volt. If the commands
VOLTage : AC
VOLTage : RANGe
Data
100 ; RANG HIGH
Message Unit Separators
Figure 7-1 The Structure of Command Message
220<PMT>
HIGH<PMT>
Root Specifier
;
: MEAS : CURR ? <NL>
Query Header
All colons are header separators.
Only the first colon is a specific root.
Only the third colon is a specific root.
Remote Operation
Message Terminator
7-5