GDM-8246 MULTIMETER
PROGRAMMER MANUAL
⎯
8
⎯
The RS232 connection testing
If you want to test whether the RS232 connection is working or not, you
can send a command from computer. For instance, using a terminal
program send the query command
*idn?
should return the Manufacturer, model number, serial number and
firmware version in the following format:
GW.Inc,GDM-8246,FW1.00
If you do not receive a proper response from the DMM, please check if
the power is on, the RS232 baud rate are the same on both sides, and all
cable connections are active.
4. INPUT AND OUTPUT QUEUE
The design of 128 bytes input queue and 128 bytes output queue for
storing the pending commands or return messages is to prevent the
transmitted commands of remote control and return messages from
missing. As the maximum stored capacity for Error/Event Queue is 20
groups of messages, it should be noted that input data exceeding the
capacity by using these buffers will cause data missing.
5. COMMANDS AND SYNTAX
The GPIB commands of the Digital Multimeter 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.
GDM-8246 MULTIMETER
PROGRAMMER MANUAL
⎯
9
⎯
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
communication, which contain the
<PROGRAM MESSAGE>
(or simply
“commands”) and
<RESPONSE MESSAGE>
. The two kinds of messages
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
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
