GW Instek PSM-Series Programming Manual User Manual
Page 6
PSM SERIES PROGRAMMABLE POWER SUPPLY
PROGRAMMER MANUAL
⎯ 9 ⎯
5. COMMANDS AND SYNTAX
The GPIB commands of the programmable power supply are compatible
with IEEE-488.2 and SCPI standards
SCPI
SCPI (Standard Commands for Programmable Instruments) is a standard
that created by an international consortium of the major test and
measurement equipment manufacturers. The IEEE-488.2
syntax has been
adopted by SCPI to provide common commands for the identical functions
of different programmable instruments.
Figure 3 the relationship between IEEE-488.1, IEEE-488.2, and SCPI
As shown in the
figure 3, the IEEE-488.1 standard locates at layer A, the
layer A belongs to the protocol of interface function on the GPIB bus. The
source handshake (SH), acceptor handshake (AH) and talker are included to
this layer (10 interface functions totally).
At layer B, the syntax and data structure could be the essence of entire
IEEE-488.2 standard. The syntax defines the function of message
SCPI
IEEE-488.2
IEEE-488.2
SCPI
IEEE-488.1
A
A
B
B
C
C
D
D
Interface Function
Syntax & Status Data Structure
Common Command & Queries
SCPI
PSM SERIES PROGRAMMABLE POWER SUPPLY
PROGRAMMER MANUAL
⎯ 10 ⎯
communication, which contain the
“commands”) and
represent the syntax formation of device command and return value. The
data structure is the constitution of status reporting, which IEEE-488.2
standard have been defined.
The common commands and queries are included to layer C. Commands
and queries can be divided into two parts: mandatory and optional.
Commands modify control settings or tell the instrument to perform a
specific action. Queries cause the instrument to send data or status
information back to the computer. A question mark at the end of a
command identifies it as a query.
Layer D is interrelated with device information. Different devices have
different functions. SCPI command sets belong to this layer.
Command Syntax
If you want to transfer any instructions to an instrument, and comply with
SCPI, there are three basic elements must be included.
z
Command header
z
Parameter (if required)
z
Message terminator or separator