GW Instek GDM-8246 User Manual

GDM-8246 MULTIMETER

PROGRAMMER MANUAL

CONTENTS PAGE

1. INTRODUCTION........................... ........... ...... ............. ........... .........

2. CONNECTING DMM VIA GPIB INTERFACE……………...

3. CONNECTING DMM VIA RS232 INTERFACE……………. 5

INPUT AND OUTPUT QUEUE………………………………..

5. COMMANDS AND SYNTAX…………………………………. 8

6. DETAILS OF COMMAND REFERENCE…………………… 21

7. STATUS AND ERROR REPORTING………………………....

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:

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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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PROGRAMMER MANUAL

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:

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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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PROGRAMMER MANUAL

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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PROGRAMMER MANUAL

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.

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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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PROGRAMMER MANUAL

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

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.

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: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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PROGRAMMER MANUAL

: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

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.

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:CALCulation:MINimum?

:CALCulation:MINimum <Boolean>

:CALCulation: RELation: STATe <NR1>

:CALCulation:RELation: STATe?

:CALCulation:RELation:DATa?

:CALCulation:RELation:DATa <NR2>

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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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