Four: Remote Operation; Introduction; Introduction To Gpib & Rs-232 (Scpi) Commands; Overview Scpi Language - Ametek Amrel PLA Series Operation Manual

FOUR: REMOTE OPERATION

INTRODUCTION

The Programming Electronic Load is provided with GPIB and RS-232 Standard Commands for Programmable
Instruments (SCPI) interface for automated testing applications. The purpose of this section is to introduce the user to
SCPI commands used to control the eLoad via remote communication.
NOTE: For a more comprehensive set of SCPI COMMANDS, please refer to the Programming Manual.
INTRODUCTION TO GPIB & RS-232 (SCPI) COMMANDS
The General Purpose Interface bus is synonymous with HP-IB standard bus used for controlling electronic instruments
with a computer. Also called IEEE 488 bus because ANSI/IEEE Standards 488 -1978 defines it, 488.1-1987, and 488.2-
1987.
Standard Commands for Programmable Instruments (SCPI) is a programming language developed to remot ely control
different test and measurement instruments over GPIB (IEEE 488) bus. SCPI functions with GPIB hardware conform to
the IEEE 488.2 Standard Digital Interface for Programmable Instrumentation. It is a device independent command set
and is layered on top of the hardware portion of IEEE 488.2. SCPI simplif ies the programming task by defining a sin gle
comprehensive command set of programmable instrumentation, regardless of type or manufacturer. The same SCPI
command can be applied to different cla sses of instruments. SCPI systems are much easier to program and maintain. In
many cases, you can interchange or upgrade instruments without having to change the test program. SCPI also applies to
RS-232 programming.
The electronic load's GPIB address ca nnot be set via GPIB bus communication or program. The address needs to be set
from the front panel keypad in the MENU function.

OVERVIEW SCPI LANGUAGE

The SCPI language uses a hierarchical structure in its programming syntax similar to an inverted tree. The command is
organized with root level commands positioned at the top, with multiple sub commands below each root -level command.
For example, VOLTage, wh ich is a branch of SOURce, is a command mnemonic and it forms a subtree of its own.
VOLTage has three sub-level commands: LEVel, SLEW, TLEVel. At the end of a sub -level command, you can attach a
parameter, a question mark (for query), a colon (command mnemonics separator), a semicolon (for multiple commands in
a message) or an end of line terminator. To execute a sub-level command, you must specify the complete path from root-
level. Each command statement is simply I/O ASCII data strings incorporated within high -level pro gramming language
(GW-BASIC, HP BASIC, Quick Basic, Pascal, etc.).
Command Mnemonics
VOLT:LEV 10;TLEV 15;:RES:TLEV? <NL>
Command Statement
M470039-01 REV-F
Data Message Terminator
Query Indicator
Root Specifier
Command Statement Separator
Command Message
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