GW Instek GPD-3303 Series User manual

DC Power Supply
GPD-3303 Series
USER MANUAL
GW INSTEK PART NO.
ISO-9001 CERTIFIED MANUFACTURER
This manual contains proprietary information, which is protected by
copyrights. All rights are reserved. No part of this manual may be
photocopied, reproduced or translated to another language without
prior written consent of Good Will company.
The information in this manual was correct at the time of printing.
However, Good Will continues to improve products and reserves the
rights to change specification, equipment, and maintenance
procedures at any time without notice.
Good Will Instrument Co., Ltd.
No. 7-1, Jhongsing Rd., Tucheng City, Taipei County 236, Taiwan.

TABLE OF CONTENTS
3
Table of Contents
SAFETY INSTRUCTIONS .................................................. 5
OVERVIEW....................................................................... 9
Introduction...........................................9
Series Lineup / Main Features ............. 11
Principle of Operation.......................... 12
Front Panel Overview ........................... 14
Rear Panel Overview ............................ 17
CV/CC Crossover Characteristics ......... 18
SETUP ........................................................................... 19
Power Up ............................................. 19
Load Cable Connection ........................ 20
Output On/Off..................................... 21
Beep On/Off ........................................ 21
Front Panel Lock .................................. 22
OPERATION .................................................................. 23
CH1/CH2 Independent Mode .............. 23
CH3 Independent Mode....................... 25
CH1/CH2 Tracking Series Mode........... 27
CH1/CH2 Tracking Parallel Mode ........ 19H32
SAVE/RECALL SETUP ..................................................... 20H34
Save Setup ........................................... 21H34
Recall Setup......................................... 22H35
REMOTE CONTROL ....................................................... 23H36
Remote Control Setup.......................... 24H36
Remote Connection Step...................... 25H37
Command Syntax ................................. 26H38
GPD-3303 Series User Manual
4
Error Messages .................................... 27H38
Command List......................................28H39
Command Details ................................29H40
FAQ................................................................................30H45
APPENDIX ......................................................................31H46
Fuse Replacement ................................ 32H46
Specifications ......................................33H47
Declaration of Conformity.................... 34H49
INDEX ............................................................................35H50

SAFETY INSTRUCTIONS
5
SAFETY INSTRUCTIONS
This chapter contains important safety instructions
that you must follow when operating the GPD-
3303 series and when keeping it in storage. Read
the following before any operation to insure your
safety and to keep the best condition for the GPD-
3303 series.
Safety Symbols
These safety symbols may appear in this manual or on the GPD-3303
series.
WARNING Warning: Identifies conditions or practices that
could result in injury or loss of life.
CAUTION Caution: Identifies conditions or practices that
could result in damage to the GPD-3303 series or
to other properties.
DANGER High Voltage
Attention Refer to the Manual
Protective Conductor Terminal
Earth (ground) Terminal
GPD-3303 Series User Manual
6
Safety Guidelines
General
Guidelines
CAUTION
•Do not place any heavy object on the GPD-3303
series.
•Avoid severe impacts or rough handling that
leads to damaging the GPD-3303 series.
•Do not discharge static electricity to the GPD-
3303 series.
•Do not block or obstruct the cooling fan vent
opening.
•Do not perform measurement at circuits directly
connected to Mains (see note below).
•Do not disassemble the GPD-3303 series unless
you are qualified as service personnel.
(Measurement categories) EN 61010-1:2001 specifies the
measurement categories and their requirements as follows. The
GPD-3303 series falls under category I.
•Measurement category IV is for measurement performed at the
source of low-voltage installation.
•Measurement category III is for measurement performed in the
building installation.
•Measurement category II is for measurement performed on the
circuits directly connected to the low voltage installation.
•Measurement category I is for measurements performed on
circuits not directly connected to Mains.
Power Supply
WARNING
•AC Input voltage: 100V/120V/220V/230V
±10%, 50/60Hz
•Connect the protective grounding conductor of
the AC power cord to an earth ground, to avoid
electrical shock.
Fuse
WARNING
•Fuse type: 100V/120V: T6.3A/250V,
220V/230V: T3.15A/250V
•Make sure the correct type of fuse is installed
before power up.

SAFETY INSTRUCTIONS
7
•To ensure fire protection, replace the fuse only
with the specified type and rating.
•Disconnect the power cord before fuse
replacement.
•Make sure the cause of fuse blowout is fixed
before fuse replacement.
Cleaning the
GPD-3303 series
•Disconnect the power cord before cleaning.
•Use a soft cloth dampened in a solution of mild
detergent and water. Do not spray any liquid.
•Do not use chemicals or cleaners containing
harsh products such as benzene, toluene, xylene,
and acetone.
Operation
Environment
•Location: Indoor, no direct sunlight, dust free,
almost non-conductive pollution (note below)
•Relative Humidity: < 80%
•Altitude: < 2000m
•Temperature: 0°C to 40°C
(Pollution Degree) EN 61010-1:2001 specifies the pollution degrees
and their requirements as follows. The GPD-3303 series falls under
degree 2.
Pollution refers to “addition of foreign matter, solid, liquid, or
gaseous (ionized gases), that may produce a reduction of dielectric
strength or surface resistivity”.
•Pollution degree 1: No pollution or only dry, non-conductive
pollution occurs. The pollution has no influence.
•Pollution degree 2: Normally only non-conductive pollution
occurs. Occasionally, however, a temporary conductivity caused
by condensation must be expected.
•Pollution degree 3: Conductive pollution occurs, or dry, non-
conductive pollution occurs which becomes conductive due to
condensation which is expected. In such conditions, equipment
is normally protected against exposure to direct sunlight,
precipitation, and full wind pressure, but neither temperature
nor humidity is controlled.
GPD-3303 Series User Manual
8
Storage
environment
•Location: Indoor
•Relative Humidity: < 70%
•Temperature: −10°C to 70°C
Power cord for the United Kingdom
When using the GPD-3303 series in the United Kingdom, make sure
the power cord meets the following safety instructions.
NOTE: This lead/appliance must only be wired by competent persons
WARNING: THIS APPLIANCE MUST BE EARTHED
IMPORTANT: The wires in this lead are coloured in accordance with the
following code:
Green/ Yellow: Earth
Blue: Neutral
Brown: Live (Phase)
As the colours of the wires in main leads may not correspond with the colours
marking identified in your plug/appliance, proceed as follows:
The wire which is coloured Green & Yellow must be connected to the Earth
terminal marked with the letter E or by the earth symbol or coloured Green or
Green & Yellow.
The wire which is coloured Blue must be connected to the terminal which is
marked with the letter N or coloured Blue or Black.
The wire which is coloured Brown must be connected to the terminal marked
with the letter L or P or coloured Brown or Red.
If in doubt, consult the instructions provided with the equipment or contact the
supplier.
This cable/appliance should be protected by a suitably rated and approved HBC
mains fuse: refer to the rating information on the equipment and/or user
instructions for details. As a guide, cable of 0.75mm2should be protected by a 3A
or 5A fuse. Larger conductors would normally require 13A types, depending on
the connection method used.
Any moulded mains connector that requires removal /replacement must be
destroyed by removal of any fuse & fuse carrier and disposed of immediately, as
a plug with bared wires is hazardous if a engaged in live socket. Any re-wiring
must be carried out in accordance with the information detailed on this label.

OVERVIEW
9
OVERVIEW
This chapter describes the GPD-3303 series in a
nutshell, including its main features and front /
rear panel introduction. After going through the
overview, follow the Setup chapter (page19) to
properly power up and set operation environment.
Introduction
Overview GPD-3303, the regulated DC power supply series,
are light weight, adjustable, multifunctional work
stations. They have three independent outputs:
two with adjustable voltage level and one with
fixed level selectable from 2.5V, 3.3V and 5V. The
GPD-3303 series can be used for logic circuits
where various output voltage or current are
needed, and for tracking mode definition systems
where plus and minus voltages with insignificant
error are required.
Independent /
Tracking Series /
Tracking Parallel
The three output modes of GPD-3303 series,
independent, tracking series, and tracking parallel,
can be selected through pressing the TRACKING
key on the front panel. In the independent mode,
the output voltage and current of each channel are
controlled separately. The isolation degree, from
output terminal to chassis or from output terminal
to output terminal, is 300V. In the tracking modes,
both the CH1 and CH2 outputs are automatically
connected in series or parallel; no need to connect
output leads. In the series mode, the output
voltage is doubled; in the parallel mode, the
output current is doubled.
GPD-3303 Series User Manual
10
Constant Voltage/
Constant Current
Except for CH3, each output channel is completely
transistorized and well-regulated, and works in
constant voltage (CV) or constant current (CC)
mode. Even at the maximum output current, a
fully rated, continuously adjustable output voltage
is provided. For a big load, the power supply can
be used as a CV source; while for a small load, a
CC source. When in the CV mode (independent or
tracking mode), output current (overload or short
circuit) can be controlled via the front panel. When
in the CC mode (independent mode only), the
maximum (ceiling) output voltage can be
controlled via the front panel. The power supply
will automatically cross over from CV to CC
operation when the output current reaches the
target value. The power supply will automatically
cross over from CC to CV when the output voltage
reaches the target value. For more details about
CV/CC mode operation, see page18.
Automatic
tracking mode
The front panel display (CH1, CH2) shows the
output voltage or current. When operating in the
tracking mode, the power supply will
automatically connect to the auto- tracking mode.
Dynamic load When used in audio production lines, the power
supply will provide a continuous or dynamic load
connector. When the connectors are connected to
the position “ON”, a stable DC current power will
be provided for audio power amplifiers.

OVERVIEW
11
Series Lineup / Main Features
Series Lineup
Model V Meter A Meter USB Tracking Error
GPD-3303D 3 digit 3 digit Yes ≤0.5% + 50mV of Master
GPD-3303S 5 digit 4 digit Yes ≤0.5% + 10mV of Master
Main Features
Performance •Low noise: Cooling fan controlled by Heatsink
temperature
•Compact size, light weight
Operation •Constant Voltage / Constant Current operation
•Tracking Series / Tracking parallel operation
•Output On/Off control
•3 outputs: 30V/3A x 2, 2.5V/3.3V/5V/3A x 1
•Digital panel control
•4 sets of panel setup save/recall
•Coarse and fine Voltage/Current control
•Software calibration
•Buzzer output
•Key lock function
Protection •Overload protection
•Reverse polarity protection
Interface •USB for remote control
GPD-3303 Series User Manual
12
Principle of Operation
Overview The power supply consists of the following.
•AC input circuit
•Transformer
•Bias power supply including rectifier, filter,
pre-regulator and reference voltage source
•Main regulator circuit including the main
rectifier and filter, series regulator, current
comparator, voltage comparator, reference
voltage amplifier, remote device and relay
control circuit
The block diagram below shows the circuit
arrangement. The single phase input power is
connected to the transformer through the input
circuit. Details of each part are described in the
next page.
Block diagram

OVERVIEW
13
Rectifier The auxiliary rectifiers D1011~ D1014 provide bias
voltage filtered by the capacitors C102 and C103,
for the pre-regulators U101 and U102. They
provide a regulated voltage for other modules.
Main Rectifier The main rectifier is a full wave bridge rectifier. It
provides the power after the rectifier is filtered by
the capacitor C101, and then regulated via a series-
wound regulator, which is finally delivered to the
output terminal.
Current Limiter U104 acts as a current limiter. When the current is
over predetermined rating, U104 is activated and
decreases the current. U208 provides a reference
voltage. U206 is the inverter amplifier. U103 is a
comparator amplifier which compares reference
voltage and feedback voltage, and then delivers to
Q103, Q104, which then calibrates the output
voltage.
Overload When the unit is overloaded, Q107 activates to
control the current magnitude of Q104, to limit the
output current. The relay control circuit controls
the power dissipation in the series-wound
regulated circuit.
GPD-3303 Series User Manual
14
Front Panel Overview
Display
VoltMeter Displays CH1 or CH2 output voltage.
GPD-3303S (5 digits)
GPD-3303D (3 digits)
AmpMeter Displays CH1 or CH2 output current.
GPD-3303S (4 digits)
GPD-3303D (3 digits)

OVERVIEW
15
Control Panel
Memory Keys
Saves or recalls panel settings. Four
settings, 1 ~ 4, are available. For
save/recall details, see page34.
CH1/CH2/Beep
Keys
Selects the output channel for level
adjustment. For level setting details,
see page23. Pressing and holding
CH2 key enables beep sound. For
details, see page21.
Parallel/Series
Keys
Activates Tracking Parallel operation
or Tracking Series operation, For
details, see page27.
Lock Key
Locks or unlocks the front panel
settings. For details, see page42H22.
Output Key
Turns the output on or off.
Voltage Knobs
Adjusts the output voltage level for
CH1 or CH2. Pressing the knob
switches coarse and fine level setting.
Current Knobs
Adjusts the output current level for
CH1 or CH2. Pressing the knob
switches coarse and fine level setting.
Power Switch
Turns On or Off the main power.
For power up sequence, see page43H19.
GPD-3303 Series User Manual
16
Terminals
Default Terminals
European Terminals
GND Terminal
Accepts a grounding wire.
CH1 Output
Outputs CH1 voltage and current.
CH1 CV/CC
Indicator
Indicates CH1 Constant Voltage or
Constant Current state.
CH2 Output
Outputs CH2 voltage and current.
CH2
CV/CC/PAR
Indicator
Indicates CH2 Constant Voltage,
Constant Current, or Tracking
Parallel operation mode.
CH3 Output
Outputs CH3 voltage and current.
CH3 Overload
Indicator Indicates when CH3 output current is
overloaded.
CH3 Voltage
Selector
Selects CH3 output voltage: 2.5V,
3.3V, or 5V.

OVERVIEW
17
Rear Panel Overview
USB Connector AC SelectorCooling Fan
Power Cord /
Fuse Socket
USB Connector
Accepts a USB slave connector for
command-based remote control
(page36).
Power Cord /
Fuse Socket
The power cord socket accepts the
AC mains: 115V/230V, 50/60Hz.
For power up details, see page19.
The fuse holder contains the AC
main fuse. For fuse replacement
details, see page46.
AC Selector
Selects AC voltage: 100V/ 120V/
220V/ 230V.
GPD-3303 Series User Manual
18
CV/CC Crossover Characteristics
Background The GPD-3303 series automatically switches
between constant voltage mode (CV) and constant
current mode (CC), according to load condition.
CV mode When the current level is smaller than the output
setting, the GPD-3303 series operates in Constant
Voltage mode. The indicator on the front panel
turns green (C.V.) The Voltage level is kept at the
setting and the Current level fluctuates according
to the load condition until it reaches the output
current setting.
CC mode When the current level reaches the output setting,
the GPD-3303 series starts operating in Constant
Current mode. The indicator on the front panel
turns red (C.C.) The Current level is kept at the
setting but the Voltage level becomes lower than
the setting, in order to suppress the output power
level from overload. When the current level
becomes lower than the setting, the GPD-3303
series goes back to the Constant Voltage mode.
Diagram
Vmax
Imax
Constant
Voltage
Constant
Current
Vout
Iout

SETUP
19
SETUP
This chapter describes how to properly power up
and configure the GPD-3303 series before
operation.
Power Up
Select AC voltage
Before powering up the power
supply, select the AC input
voltage from the rear panel.
Connect AC
power cord
Connect the AC power cord to
the rear panel socket.
Power On Press the Power switch to turn
on the power. The display shows
the initialization screen with the
model name, followed by the
last recalled settings.
Power Off Press the Power switch again to
turn off the power.
GPD-3303 Series User Manual
20
Load Cable Connection
GTL-104 1. Turn the terminal
counterclockwise and loosen
the screw.
2. Insert the cable terminal.
3. Turn the terminal clockwise
and tighten the screw.
GTL-105 Insert the plug into the socket.
GTL-203, 204 Insert the plug into the terminal.
Wire type When using load cables other than the attached,
make sure they have enough current capacity for
minimizing cable loss and load line impedance.
Voltage drop across a wire should not excess 0.5V.
The following list is the wire current rating at
450A/cm2.
Wire size (AWG) Maximum current (A)
20 2.5
18 4
16 6
14 10
12 16

SETUP
21
Output On/Off
Panel operation Pressing the Output key turns
on all CH 1/2/3 outputs.
The key LED also turns on. Pressing the Output
key again turns the output and the key LED off.
Automatic output
off
Any of the following actions during output on
automatically turns it off. They might involve
sudden and harmful change in the output level.
•Change the operation mode between
independent / tracking series / tracking parallel
•Recalling other setups from the memory
•Storing the setup into the memory
Beep On/Off
Panel operation By default, the beep sound is
enabled. To turn off the beep,
press the CH2 key for 2 seconds.
A beep comes out and the beep setting will be
turned off. To enable the beep, press the CH2 key
again for 2 seconds.
List of beep The following operations beep when the beep
setting is on.
•Power on
•INDEP – SER – PARA
mode switching
•Setup save/recall
•Voltage/current knob
fine/coarse switching
•Output on/off
•Panel lock/unlock
•CH1/CH2 output
level knob switching
•Voltage/current level
reaching minimum
(zero) level
GPD-3303 Series User Manual
22
Front Panel Lock
Panel operation Press the LOCK key to lock
the front panel key
operation. The key LED
turns on. To unlock, press the LOCK key for 2
seconds. The key LED also turns off.
Note The OUTPUT key is not
affected by the lock
operation.

OPERATION
23
OPERATION
CH1/CH2 Independent Mode
Background /
Connection
CH1 and CH2 outputs work independent of each
other.
Output rating 0 ~ 30V/0~3A for each channel
Panel operation 1. Make sure the PARA/
INDEP and SER/INDEP
keys are turned off (the key
LEDs are off).
2. Connect the load to the front panel terminals,
CH1 +/−, CH2 +/−.
GPD-3303 Series User Manual
24
Note: this diagram shows non-European terminals.
3. Set the CH1 output voltage
and current. Press the CH1
key (LED turns on) and then
use the Voltage and Current
knob.
By default, the Voltage and
Current knob work in the
coarse mode. To activate the
fine mode, press the knob to
turn the FINE LED on.
(For CH1)
(Fine control)
•Coarse: 0.1V or 0.1A @ rotation click
•Fine: the smallest digit @ rotation click
4. Repeat the above settings for the CH2.
5. To turn on the output, press
the output key. The key
LED turns on and the CH1 /
CH2 indicator shows the
output mode, CV or CC.
(CH1)
(CH2)

OPERATION
25
CH3 Independent Mode
Background /
Connection
The CH3 rating is 2.5V/3.3V/5V, 3A fixed. It
works independently from CH1 and CH2,
regardless of their modes.
Output rating 2.5V/3.3V/5V, 3A fixed
No Tracking
Series/Parallel
CH3 does not have tracking series/parallel mode.
Also, CH3 output is not affected by CH1 and CH2
modes.
Panel operation 1. Connect the load to the front
panel CH3 +/−terminal.
(the diagram shows non-
European terminals)
2. Select the output voltage,
2.5V/3.3V/5V using the
CH3 voltage selector key.
GPD-3303 Series User Manual
26
3. To turn on the output, press
the output key. The key
LED turns on.
CV →CC When the output Current level
exceeds 3A, the overload
indicator turns red and CH3
operation mode switches from
Constant Voltage to Constant
Current.
Note: “overload” in this case does not mean an
abnormal operation.

OPERATION
27
CH1/CH2 Tracking Series Mode
Background Tracking series operation doubles the Voltage
capacity of the GPD-3303 series by internally
connecting CH1 (Master) and CH2 (Slave) in serial
and combining the output to a single channel. CH1
(Master) controls the combined Voltage output
level.
The following describes two type of configurations
depending on the common ground usage.
Tracking series without common terminal
Connection
Output rating 0 ~ 60V/0 ~ 3A
1. Press the SER/INDEP key
to activate the tracking
series mode. The key LED
turns on.
GPD-3303 Series User Manual
28
2. Connect the load to the front panel terminals,
CH1+ & CH2−(Single supply).
Note: this diagram shows non-European terminals.
3. Press the CH2 key (LED
turns on) and then use the
Current knob to set the CH2
output current to the
maximum level (3.0A).
By default, the Voltage and
Current knob work in the
coarse mode. To activate the
fine mode, press the knob to
turn the FINE LED on.
(Fine control)
•Coarse: 0.1V or 0.1A @ rotation click
•Fine: the smallest digit @ rotation click
4. Press the CH1 key (LED
turns on) and then use the
Voltage and Current knob
to set the output voltage
and current level.
5. To turn on the output, press
the output key. The key LED
turns on.
6. Refer to the CH1 (Master) meter and indicator
for the output setting level and CV/CC status.

OPERATION
29
Voltage level
Double the reading on the CH1
Voltage meter. In the above
case, the actual output is 20.0 x 2
= 40.0V.
Current level
CH1 meter reading shows the
output Current. In the above
case, 2.000A. (CH2 Current
control must be in the
Maximum position=3.0A).
Tracking series with common terminal
Connection
Output rating 0~30V/0~3A for CH1 ~ COM
0~–30V/0~3A for CH2 ~ COM
GPD-3303 Series User Manual
30
1. Press the SER/INDEP key to
activate the tracking series
mode. The key LED turns on.
2. Connect the load to the front panel terminals,
CH1+ & CH2−. Use the CH1 (−) terminal as the
common line connection.
Note: this diagram shows non-European terminals.
3. Press the CH1 key (LED turns
on) and use the Voltage knob
to set the master & slave
output voltage (the same level
for both channels).
By default, the Voltage and
Current knob work in the
coarse mode. To activate the
fine mode, press the knob to
turn the FINE LED on.
(master & slave)
(Fine control)
•Coarse: 0.1V or 0.1A @ rotation click
•Fine: the smallest digit @ rotation click
4. Use the Current knob to set
the master output current.
5. To turn on the output (and
LED), press the output key.

OPERATION
31
6. For the master (CH1) output level and CV/CC
status, refer to the CH1 meter and indicator.
Master (CH1)
voltage level
CH1 meter reading shows the
output voltage. In the above case,
20.0V.
Master (CH1)
current level
CH1 meter reading shows the
output current. In the above case,
2.000A.
7. Press the CH2 key (LED turns
on) and use the Current knob
to set the slave output current.
8. For the slave (CH2) output level and CV/CC
status, refer to the CH1/CH2 meter and CH2
indicator.
Slave (CH2)
voltage level
The CH2 meter reading shows
the output voltage. In the above
case, 20.0V.
Slave (CH2)
current level
The CH2 meter reading shows
the output current. In the above
case, 3.000A.
GPD-3303 Series User Manual
32
CH1/CH2 Tracking Parallel Mode
Background /
Connection
Tracking parallel operation doubles the current
capacity of the GPD-3303 series by internally
connecting CH1 and CH2 in parallel and
combining the output to a single channel. CH1
controls the combined output.
Output rating 0 ~ 30V/0 ~ 6A
1. Press the PARA/INDEP key
to activate the tracking
parallel mode. The key LED
turns on.
2. Connect the load to the CH1 +/−terminals.
Note: this diagram shows non-European terminals.

OPERATION
33
3. To turn on the output, press
the output key. The key
LED turns on.
4. The CH2 indicator turns
red, indicating tracking
parallel (PARA) mode.
5. Press the CH1 key (LED
turns on) and then use the
Voltage and Current knob
to set the output voltage
and current. The CH2
output control is disabled.
By default, the Voltage and
Current knob work in the
coarse mode. To activate the
fine mode, press the knob to
turn the FINE LED on.
(Fine control)
6. For the output level and CV/CC status, refer to
the CH1 meter and indicator.
Voltage level
The CH1 meter reading shows
the output voltage. In the above
case, 20.0V.
Current level
Double the amount of CH1
current meter reading. In the
above case, 2.0A x 2 = 4.0A.
GPD-3303 Series User Manual
34
SAVE/RECALL SETUP
Save Setup
Background The front panel settings can be stored into one of
the four internal memories.
Contents The following list shows the setup contents.
•Independent / tracking series / tracking parallel
mode
•CH1/CH2 knob selection
•Fine/coarse editing mode
•Output voltage/current level
The following settings are always saved as “off”.
•Output on/off
•Front panel lock/unlock
Panel operation Press one of the 1~4 Memory
keys for 2 seconds, for example
memory 1. The panel settings
are saved in memory 1 and the
key LED turns on. When the
panel settings are modified, the
LED turns off.
Note When a setting is stored, the output automatically
turns off.

SAVE/RECALL SETUP
35
Recall Setup
Background The front panel settings can be recalled from one of
the four internal memories.
Contents The following list shows the setup contents.
•Independent / tracking series / tracking parallel
mode
•CH1/CH2 knob selection
•Fine/coarse editing mode
•Output voltage/current level
The following settings are always recalled as “off”.
•Output on/off
•Front panel lock/unlock
Panel operation Press one of the 1~4 Memory
keys, for example memory 1.
The panel settings saved in
memory 1 are recalled. The key
LED turns on. When the panel
settings are modified, the LED
turns off.
Note When a setting is recalled, the output
automatically turns off.
GPD-3303 Series User Manual
36
REMOTE CONTROL
Remote Control Setup
Background The GPD-3303D and GPD-3303S are capable of
being remotely controlled via the USB connection.
Interface
USB slave port, rear panel
COM setting Set up the COM port inside the PC according to
the following list.
•Baud rate: 9600
•Parity bit: None
•Data bit: 8
•Stop bit: 1
•Data flow control: None
Functionality
check
Run this query command via the terminal
application such as MTTTY (Multi-threaded TTY).
*IDN?
This should return the identification information:
Manufacturer, model name, serial number,
firmware version.
GW INSTEK, GPD-3303x, SN: xxxxxxxx, Vx.xx

REMOTE CONTROL
37
Remote Connection Step
Entering the
remote control
mode
1. Connect the USB cable to the slave port.
2. The connection will be automatically
established, and the front panel shows
“USB…YES” message.
3. The power supply also automatically enters the
lock state (the Lock key will become activated).
Leaving the
remote control
mode
1. Disconnect the USB cable from the rear.
2. The display shows “USB…NO” message.
3. Unlock the power supply by keep pressing the
Lock key until it turns off.
4. The power supply goes back to the local
operation mode.
GPD-3303 Series User Manual
38
Command Syntax
Command format
1: command header
2: output channel
3: separator
4: parameter
Output channel 1 (CH1) or 2 (CH2)
Parameter Type Description Example
<Boolean>
boolean logic 0 (off), 1 (on)
<NR1>
integers 0, 1, 2, 3
<NR2>
decimal numbers
0.1, 3.14, 8.5
Note Commands are not case-sensitive.
Error Messages
The following error messages might appear when the GPS-3303D or
3303S cannot accept the command.
Message contents Descriptions
Program mnemonic
too long
The command length must be 15 characters
or less.
Invalid character Invalid characters, such as symbols, are
entered. Example: VOUT#
Missing parameter The parameter is missing from the command.
Example: VSET: (should have a number)
Data out of range The entered value exceeds the specification.
Example: VSET:33 (should be ≤32V)
Command not allowed
The entered command is not allowed in the
circumstance. Example: trying to set CH2
output while in the tracking mode.
Undefined header The entered command does not exist, or the
syntax is wrong.

REMOTE CONTROL
39
Command List
•Detailed descriptions of each command start from the next page.
•The “HELP” command shows all the below commands and their
meanings, except for the HELP command itself.
ISET<X>:<NR2> Sets the output current.
ISET<X>? Returns the output current setting.
VSET<X>:<NR2> Sets the output voltage.
VSET<X>? Returns the output voltage setting.
IOUT<X>? Returns the actual output current.
VOUT<X>? Returns the actual output voltage.
TRACK<NR1> Selects the operation mode.
BEEP<BOOLEAN> Turn on or off the beep.
OUT<BOOLEAN> Turn on or off the output.
STATUS? Returns the GPS-3303D or GPS-3303S status.
*IDN? Returns the GPS-3303D or GPD-3303S
identification.
RCL<NR1> Recalls a panel setting.
SAV<NR1> Saves the panel setting.
HELP? Shows the command list.
ERR? Returns the instrument error messages.
GPD-3303 Series User Manual
40
Command Details
ISET<X>:<NR2>
Description Sets the output current.
Panel operation See page23
Response time Minimum 70ms
Example ISET1:2.234
ISET1:2.23
Sets the CH1 output current to
2.234A (for GPD-3303S)
Sets the CH1 output current to
2.23A (for GPD-3303D)
ISET<X>?
Description Returns the output current setting.
Panel operation See page23
Response time Minimum 80ms
Example ISET1?
Returns the CH1 output current setting
VSET<X>:<NR2>
Description Sets the output voltage.
Panel operation See page23
Response time Minimum 70ms
Example VSET1:20.345
VSET1:20.3
Sets the CH1 voltage to 20.345V
(for GPD-3303S)
Sets the CH1 voltage to 20.3V
(for GPD-3303D)