GW Instek GDM-8246 User Manual
GDM-8246 MULTIMETER
GDM-8246 MULTIMETER
PROGRAMMER MANUAL
CONTENTS PAGE
1. INTRODUCTION........................... ........... ...... ............. ........... .........
1
2. CONNECTING DMM VIA GPIB INTERFACE……………...
2
3. CONNECTING DMM VIA RS232 INTERFACE……………. 5
4.
INPUT AND OUTPUT QUEUE………………………………..
8
5. COMMANDS AND SYNTAX…………………………………. 8
6. DETAILS OF COMMAND REFERENCE…………………… 21
7. STATUS AND ERROR REPORTING………………………....
46
PROGRAMMER MANUAL
1. INTRODUCTION
In the modern automatic measurement system, communication
between equipments and computers is essential. The measured
procedures can be varied with user’s testing programs, therefore, the
Digital Multimeter can be operated remotely from an instrument
controller or computer across the RS232 interface (optional) or GPIB
(optional).
Interface selection and setup
Press [SHIFT][SET] in sequence into SET mode, then press [RS-232] or
[GPIB] the white characters with blue background to set the RS232 OR
GPIB interface. If the indicator of negative sine lights, the value
displayed on the front panel is the current setting value. Use [▲][▼] can
adjust the baud rate (or GPIB address). Finally, press [ENTER] to store
the setup or pres s [SH IF T] to c anc el th e s etup .
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2. CONNECTING THE DIGITAL MULTIMETER VIA
GPIB INTERFACE
The GPIB interface capabilities:
The GPIB interface of the Digital Multimeter corresponds to the
standard of IEEE488.1-1987, IEEE488.2-1992 and SCPI-1994. The
GPIB interface functions are listed as follows:
SH1(Source Handshake) : The DMM can transmit multilane
messages across the GPIB.
AH1(Acceptor Handshake) : The DMM can receive multilane
messages across the GPIB.
T6(Talker) : Talker interface function includes basic
talker, serial poll, and unaddress if MLA
capabilities, without talk only mode
function.
L4 (Listener) : The DMM becomes a listener when the
controller sends its listen address with
the ATN (attention) line asserted. The
DMM does not have listen only
capability.
SR1 (Service Request) : The DMM asserts the SRQ (Service
request) line to notify the controller
when it requires service.
RL1 (Remote/Local) : The DMM responds to both the GTL(Go
to Local) and LLO(Local Lock Out)
interface messages.
PP0 (Parallel Poll) : The DMM has no Parallel Poll interface
function.
DC1 (Device Clear) : The DMM has Device clear capability to
return the device to power on status.
DT0 (Device Trigger) : The DMM has no Device Trigger
interface function.
C0 (Controller) : The DMM can not control other devices.
PROGRAMMER MANUAL
Notes for GPIB installation
When the Digital Multimeter is set up with a GPIB system, please check
the following th i ngs :
z Only a maximum of 15 devices can be connected to a single GPIB
bus.
z Do not use more than 20m of cable to connect devices to a bus.
z Connect one device for every 2m of cable used.
z Each device on the bus needs a unique device address. No two
devices can share the same device address.
z Turn on at least two-thirds of the devices on the GPIB system while
using the system.
z Do not use loop or parallel structure for the topology of GPIB
system.
Computer’s Connection
A personal computer with a GPIB card is the essential facilities in order
to operate the Digital Multimeter via GPIB interface.
The connections between DMM and co mp uter ar e following :
I. Connect one end of a GPIB cable to the computer.
II. Connect the other end of the GPIB cable to the GPIB port on
the Digital Multimeter.
Turn on the Digital Multimeter.
Turn on the computer.
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The GPIB connection testing
If you want to test whether the GPIB connection is working or not, you
can send a GPIB command from computer. For instance, the query
command
*idn?
should return the Manufacturer, model 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 GPIB address is correct, and all cable connections
are active.
PROGRAMMER MANUAL
3. CONNECTING THE DIGITAL MULTIMETER VIA
RS232 INTERFACE
The RS232 interface capabilities:
The RS232 interface provides a point-to-point connection between two
items of equipment such as a comp uter and the DMM. There are some
parameters you need to set on the both sides. Once you have set these
parameters, you can control the DMM through the RS232 interface.
z Baud rate: You can set rates of 1200, 2400, 4800 or 9600 baud.
z Parity bit: none.
z Data bit: 8 bits.
z Stop bit: 1 stop bit.
z Data flow control: none.
Notes for RS232 installation
The DMM is a DTE device with a 9-pin D-type shell RS232 connector
located on the rear panel. Figure 1 shows the equipment of 9-pin
connector (male) with its pin number assignments. Figure 2 shows the
wiring configuration for DB9 to DB9. When the Digital Multimeter is set
up with a RS232 interface, please check the following points:
⎯ 4 ⎯
z Do not connect the output line of one DTE device to the output line
of the other.
z Many devices require a constant high signal on one o r more input
pins.
z Ensure that the signal ground of the equipment is connected to the
signal ground of the external device.
z Ensure that the chassis ground of the equ ipment is connected to the
chassis ground of the external device.
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z Do not use more than 15m of cable to connect devices to a PC.
z Ensure the same baud rate is used on the device a s the one used on
PC terminal.
z Ensure the connector for the both side of cable and the internal
connected line are met the demand of the instrument.
1. No connection
2. Receive Data(RxD) (input)
3. Transmit Data(TxD) (output)
4. No connection
5. Signal Ground(GND)
6. No connection
7. No connection
8. No connection
9. No connection
Figure 1 Pin assignments of the RS232 connector on the rear panel for DB-9-D
PROGRAMMER MANUAL
EQUIPMENT
(DB9, DTE)
Pin2
Pin3
COMPUTER
(DB9, DTE)
Pin2
Pin3
Pin5 Pin5
Figure 2 Wiring configuration for DB9 to DB9
Computer’s Connection
A personal computer with a COM port is the essential facilities in order
to operate the Digital Multimeter via RS232 interface.
The connections between DMM and co mp uter are a s follows:
⎯ 6 ⎯
I. Connect one end of a RS232 cable to the computer.
II. Connect the other end of the cable to the RS232 port on the
Digital Multimeter.
III. Turn on the Digital Multimeter.
IV. Turn on the computer.
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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
adopted by SCPI to provide common commands for the identical
functions of different programmable instruments.
syntax has been
PROGRAMMER MANUAL
Figure 3 the relationship between IEEE-488.1, IEEE-488.2, and SCPI
SCPI
Common Command & Queries
Syntax & Status Data Structure
IEEE-488.2 IEEE-488.2
SCPI
Interface Function
AABBCCDD
SCPIIEEE-488.1
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 in terface 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 quer ies 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
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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
Command Header
The command header ha s a hierarchical structure that can be represented
by a command tree (Figure 4).
The top level of the tree is the root level. A root node is located at the
root level. A root node and one or more lower-level nodes form a header
path to the last node called the leaf node.
:SYSTem
Root node
:ERRor
:AUTO
Lower-level node
:STATe :STARt :CYCLe
Leaf Node
Figure 4: Tree hierarchy
PROGRAMMER MANUAL
The command header is configured b y header path and leaf node. Figure 5
shows the command header for the leaf node indicated in Figure 4.
Figure 5 Command Header
Parameter
If the commands have parameters, the values have to be included. In this
manual, when we expressed the syntax of the command, the < > symbols
are used for enclosing the parameter type. For instance, the syntax of the
command in Figure 6 includes the Boolean parameter type.
NOTE: Do not include the <, >, or | symbols when entering the actual
value for a parameter.
Figure 6 Command Header with Parameter
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Table 1 defines the Boolean and other parameter types for the Digital
Multimeter.
Parameter Type Description Example
Boolean Boolean numbers or
0, 1
values
NR1 Integers 0, 1, 18
NR2 Decimal numbers 1.5, 3.141, 8.4
NR3 Floating point numbers 4.5E-1, 8.25E+1
String Alphanumeric characters “No error”
Table 1: Parameter Type s for Sy ntax Desc ript ions
Message Terminator and Message Separator
I. GPIB message terminators
In accordance with IEEE 488.2 standard, any of the following message
terminators are acceptable:
^
z LF
END Line feed code (hexadecimal 0A) with END
message
PROGRAMMER MANUAL
II. RS232 message terminators
As there is no signal of end message on RS232 bus, therefore, use LF
as message terminator. When a series of commands are sent to the
instrument, it must add a LF to be a judgment for message terminator.
As for query command, the return message of the instrument is also
added a LF for PC to judge message terminator.
Entering Commands
The standards that govern the command set for the Digital Multimeter
allow for a certain amount of flexibility when you enter commands. For
instance, you can abbreviate many commands or combine commands
into one message that you send to the Digital Multimeter. This
flexibility, called friendly listening, saves programming time and makes
the command set easier to remember and use.
Command Characters
The DMM is not sensitive to the case of command characters. You can
enter commands in either uppercase or lowercase.
You can execute any command with white space char acters. You must,
however, use at least one space between the parameter and the command
header
z LF Line feed code
z <dab>
^
END Last data byte with END message
These terminators are compatible with most application programs. A
semicolon separates one co mmand from another when the commands
appear on the same line.
⎯ 12 ⎯
Abbreviating Commands
Most commands have a long form and a short form. The listing for
each command in this section shows the abbreviations in uppercase.
For instance, you can enter the query :CONFigure:VOLTage:DC 0
simply as :CONF:VOLT:DC 0
Because the Digital Multimeter hypothesis that a command starts from
the root, you have the option of beginning the initial command header
with a colon (:).
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Combining Commands
You can use a semicolon (;) to combine commands. But continuously
query command will cause message missing. For example:
:READ?;:VAL?
If the command that follows the semicolon has a different header path
from the root level, you must use a colon to force a return to the root
level:
:CONF:VOLT:DC 0;:CALC:SDBM:STAT 1
If the command that follows th e semico lon has the sa me head er path, you
may omit the colon and the path and state only the new leaf node. For
example:
: CONF:VOLT:DC 0;:CONF:CURR:DC 0
is equal to
: CONF:VOLT:DC 0;:CURR:DC 0
You can combine commands and queries into the same message. Note,
for example, the following combination:
PROGRAMMER MANUAL
z
General Setting Commands
Table 2 lists the general setting commands that control and query the
settings of the DMM.
Table 2: General Setting Commands
Command Explanation
:CONFigure:AUTo? Returns Auto-range mode on or off.
:CONFigure:AUTo <Beolean> Sets Auto-range mode on or off.
:CONFigure:RANGe? Returns the range of the present
function.
:CONFigure:MODe? Returns the total value of the
selected calculation mode.
:CONFigure:FUNCtion? Returns the present selected
function.
:CONFigure:CAPacitance <NR2> Sets capacitance function and range.
:CONFigure:CONTinuity Sets continuity function.
: CONF:VOLT:DC 0;:READ?
Synopsis of Commands
The tables in this section summarize the command of the Digital
Multimeter. These tables divide the commands into four functional
classifications:
z General Setting Commands
z Calculating Commands.
z Status Commands
z Miscellaneous Commands
The tables also provide a brief explanation of each command.
⎯ 14 ⎯
:CONFigure:CURRent:AC <NR2> Sets AC current function and range.
:CONFigure:CURRent:DC <NR2> Sets DC current function and range.
:CONFigure:CURRent:ACDC <NR2> Sets AC+DC current function and
range.
:CONFigure:DIODe Sets diode function.
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:CONFigure:SFRequency Sets frequency function.
:CONFigure:RESistance <NR2> Sets resistance function and range.
:CONFigure:VOLTage:AC <NR2> Sets AC voltage function and range.
:CONFigure:VOLTage:DC <NR2> Sets DC voltage function and range.
:CONFigure:VOLTage:ACDC <NR2> Sets AC+DC voltage function and
range.
:CONFigure:VOLTage:DCAC <NR2> Sets Ripple voltage function and
range.
:READ? Returns the value displayed on the
primary and secondary display
:VALue? Returns the value displayed on the
primary display.
:SVALue? Returns the value displayed on the
secondary display.
PROGRAMMER MANUAL
z
Calculation Commands
:CALCulation: LIMit:STATe? Returns Compare mode on or off.
:CALCulation: LIMit:STATe <Boolean>
:CALCulation: LIMit:LOWer?
:CALCulation: LIMit:LOWer <NR2>
:CALCulation: LIMit:UPPer?
:CALCulation: LIMit:UPPer <NR2>
:CALCulation: LIMit:FAIL?
:CALCulation:MAXimum?
:CALCulation:MAXimum <Boolean>
Sets Compare mode on or off.
Returns the value of the lower
limit.
Sets the value of the lower limit.
Returns the value of the upper
limit.
Sets the value of the upper limit.
Returns the limit result.
Returns the MAX mode on or
off.
Sets the MAX mode on or off.
⎯ 16 ⎯
:CALCulation:MINimum?
:CALCulation:MINimum <Boolean>
:CALCulation: RELation: STATe <NR1>
:CALCulation:RELation: STATe?
:CALCulation:RELation:DATa?
:CALCulation:RELation:DATa <NR2>
⎯ 17 ⎯
Returns the MIN mode on or off.
Sets the MIN mode on or off.
Sets REL mode on or off.
Returns REL mode on or off.
Returns the reference value of
the REL mode.
Sets the reference value of the
REL mode.
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