B&K Precision 8500, 8502, 8510, 8512, 8514, 8518, 8520, 8522, 8524 ,8526 User manual

USER MANUAL

8500 SERIES DC ELECTRONIC LOADS

Models 8500, 8502, 8510, 8512, 8514, 8518, 8520,
8522, 8524 & 8526

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Safety

WARNING

CAUTION

The following general safety precautions must be observed during all phases of operation of this instrument.
Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the instrument. B&K Precision assumes no liability for
the customer’s failure to comply with these requirements.

Verify that all safety precautions are taken. Note the instrument's external markings described under "Safety
Symbols".

This product is a Safety Class 1 instrument, which means it is provided with a protective earth terminal. To
minimize shock hazard, the instrument chassis and cover must be connected to an electrical ground. The
instrument must be connected to the AC line power through a grounded power cable, with the ground wire
firmly connected to an electrical ground (safety ground) at the power outlet. Note: Any interruption of the
protective (grounding) conductor or disconnection of the protective earth terminal will cause a potential shock
hazard that could result in personal injury.

DO NOT OPERATE THE INSTRUMENT IN AN EXPLOSIVE ATMOSPHERE OR IN THE PRESENCE OF
FUMES OR FLAMMABLE GASES.

KEEP AWAY FROM LIVE CIRCUITS.

Operating personnel must not remove instrument covers. Component replacement and internal adjustments
must be made only by qualified service personnel. Do not replace components with the power cable
connected. Under certain conditions, dangerous voltages may exist even with the power cable removed. To
avoid injuries always disconnect power, discharge circuits and capacitors, and remove external voltage
sources before touching components.

DO NOT SERVICE OR ADJUST ALONE.

Do not try to perform internal service or adjustment unless another person capable of rendering first aid and
resuscitation is present.

Safety Symbols

Note the instrument's external markings as follows:

Direct current

Alternating current

Both direct and alternating current

Protective earth (ground) terminal

Caution (refer to accompanying documents)

The WARNING sign denotes a hazard. It calls attention to a procedure, practice,
or the like which, if not correctly performed or adhered to, could result in
personal injury. Do not proceed beyond a WARNING sign until the indicated
conditions are fully understood and met.

The CAUTION sign denotes a hazard. It calls attention to an operating
procedure, or the like, which, if not correctly performed or adhered to, could
result in damage to or destruction of part or all of the product. Do not proceed
beyond a CAUTION sign until the indicated conditions are fully understood and
met.

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Table of Contents

Safety...................................................................................................................................................... 2

Safety Symbols................................................................................................................................... 2

Notation................................................................................................................................................... 5

Quick reference...................................................................................................................................... 6

Model numbers covered by this document..........................................................................................6

Options and accessories..................................................................................................................... 6

Overview of instrument.......................................................................................................................6

Typical tasks....................................................................................................................................... 7

Front panel.......................................................................................................................................... 7

Standard display.................................................................................................................................9

Front panel keys................................................................................................................................. 9

Rear panel........................................................................................................................................ 10

Power Requirements........................................................................................................................ 11

Display annunciators......................................................................................................................... 11

Menus............................................................................................................................................... 12

Specifications........................................................................................................................................16

Environmental Conditions ................................................................................................................ 18

Internal Resistances..................................................................................................................... 18

Operational power curve..............................................................................................................19

Low Voltage Characteristics......................................................................................................... 20

Slew rate...................................................................................................................................... 21

Glossary................................................................................................................................................ 23

Installation.............................................................................................................................................25

Inspection......................................................................................................................................... 25

Items you should have received................................................................................................... 25

Instrument location............................................................................................................................ 25

Outline Drawings............................................................................................................................... 25

Bench operation................................................................................................................................ 28

First turn-on checkout.......................................................................................................................29

Operational introduction.................................................................................................................... 30

Power-on state.................................................................................................................................. 31

Constant current mode..................................................................................................................... 32

Constant voltage mode..................................................................................................................... 32

Constant power mode....................................................................................................................... 32

Constant resistance mode................................................................................................................33

Timed operation................................................................................................................................ 33

Changing display resolution.............................................................................................................. 34

Increasing current resolution........................................................................................................34

Increasing voltage resolution........................................................................................................ 34

Short................................................................................................................................................. 34

Battery test........................................................................................................................................ 34

Transient operation........................................................................................................................... 35

Continuous transient operation.....................................................................................................35

Pulse transient operation.............................................................................................................. 36

Toggled transient operation.......................................................................................................... 37

Toggle between two test values...................................................................................................38

Lists (dynamic condition)...................................................................................................................38

Test files........................................................................................................................................... 40

Triggering.......................................................................................................................................... 42

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Voltage threshold operation.............................................................................................................. 42

Passwords........................................................................................................................................ 43

Protection features............................................................................................................................ 43

Over Voltage protection................................................................................................................ 43

Over Current protection................................................................................................................ 43

Over Power protection ................................................................................................................. 44

Reverse voltage protection........................................................................................................... 44

Over Temperature protection.......................................................................................................44

Remote sensing................................................................................................................................ 44

Saving and Recalling settings........................................................................................................... 45

Remote operation.................................................................................................................................. 46

Communication cables...................................................................................................................... 46

USB to TTL serial converter cable IT-E132B................................................................................46

USB (Virtual COM) settings..............................................................................................................46

Overview of DC Load programming.................................................................................................. 46

Packet structure........................................................................................................................... 46

Status packets.............................................................................................................................. 47

Chapter organization.................................................................................................................... 50

Summary of commands.................................................................................................................... 50

Command details.............................................................................................................................. 53

Serial number and firmware version...................................................................................................... 70

In case of trouble................................................................................................................................... 71

Instrument won't turn on.................................................................................................................... 71

Error messages during power-up...................................................................................................... 71

Keypad unlock procedure (Keypad was accidentally locked)............................................................71

Frequency Asked Questions............................................................................................................. 72

Appendix: Service and warranty information......................................................................................... 74

Index..................................................................................................................................................... 75

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Notation

I-set Represents a key on the front panel. Note that some of these may be

accessed in combination with the Shift key.

OFF Annunciator, value, or message shown on the vacuum fluorescent

display.

CONFIG Menu item

OFF

Default menu item

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Quick reference

Model numbers covered by this document

The B&K Precision DC Loads covered by this manual are:

● 8500

● 8502

● 8510

● 8512

● 8514

● 8518

● 8520

● 8522

● 8524

● 8526

Unless otherwise noted, this document will refer to all of these instruments as the DC Load.

Instrument differences, where appropriate, will be noted.

Options and accessories

The items included with the instrument are:

1. Power cord

2. User manual

3. Installation CD with application software PV8500 and USB driver for TTL to USB adapter

4. TTL to USB serial adapter IT-E132B

5. Test report

Optional accessories are:

6. rack mount kit IT-E151 (available for models 8500, 8502, 8510, 8512, 8514, 8518)

Overview of instrument

The DC Load is a two terminal device that can be connected to DC sources. Here, a DC source is a

voltage that is always positive on the DC Load's + terminal referenced to the - terminal.

DC Electronic Loads are used for design, manufacturing and evaluation of DC power supplies,

batteries, and power components. Other applications include fuel-cell and photovoltaic cell test. The

DC Load can operate under the following modes:

● Draw a constant voltage from a DC source.

● Draw a constant current from a DC source.

● Draw a constant power from a DC source.

● Present a constant resistance to the DC source (this behavior simulates a perfect resistor

whose resistance doesn't change as a function of current or voltage).

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The DC Load can present dynamically changing loads to the DC source with millisecond switching

times. The DC Load can be remotely programmed via a serial interface ( USB virtual COM).

Versatile triggering options allow the dynamic load behavior to be synchronized with other events.

A battery test mode is provided that will measure the ampere*hour (A*hr) characteristic of a battery.

Shorts can be simulated by either the front panel or custom programming. The DC source or other

components can be protected from excessive voltage, current, or power, which will cause the DC

Load to shut down if excessive levels or reverse polarity are detected.

Dynamic profiles and last instrument states can be stored in non-volatile memory.

The DC Load is a versatile instrument for static and dynamic testing of power supplies, batteries, DC

to DC converters, and battery chargers.

Typical tasks

To perform the following tasks, consult the indicated sections

Task Section(s)

Manual on/off CC, CV, CW, or CR test Constant current mode

Constant voltage mode
Constant power mode
Constant resistance mode

Timed on/off CC, CV, CW, or CR test Constant current mode

Constant voltage mode
Constant power mode
Constant resistance mode
Timed operation

Triggered CC, CV, CW, or CR test Constant current mode

Constant voltage mode
Constant power mode
Constant resistance mode
Triggering

Constant load with one transient Transient operation

Load with multiple transients Lists (dynamic condition)

Determine A*hr characteristic of battery Battery test

Run a sequence of tests Test files

Front panel

The following picture is the front panel for the 8510 DC Load. All models have the same front panel,

only the terminal section will vary based on the model.

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6

1

2

3 4 5

1

2

3

4

5

6

Button Function(s)

16-character display shows voltage and current measurements.
Rotary knob. Turn to adjust a setting value. Press in to toggle between setting the

currently-selected mode's value and reading the voltage and current, as shown in
the above picture.

Power switch to turn the instrument on or off.
Numeric keypad:

Numeric entry keys.
Secondary key functions.

Keypad:

Enable/disable input.
Set up the current, voltage, power, and resistance modes.
Scroll through menus and options.

Input terminals. Depending on the model, you will have different types and
numbers of input terminals.
Models 8500/8502 come with one plus and one minus terminal
Models 8510/8512 come with two positive and two negative terminals however
each terminal is able to sink the maximum current supported by the instrument.
Thus, it is not necessary to double up on the wires when sinking a high current
unless you wish to.
Models 8514/8518 also come with two positive and two negative terminals however
it is required to double up on the wires when sinking a current exceeding 120A.
Models 852x come with a screw terminal block to connect the wires

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Standard display

1

4

2

8 9

6 05

7

3 ESC

I-set V-set

R-set

Input on/off

Shift

P-set ENTER

POWER

A B

Tran

Store Recall S-Tran Menu

Local Battery Short Trigger

The standard display for the instrument is the voltage and current at the instrument's terminals. You

may press the △ or ▽ keys to see the instantaneous power and the mode's parameter setting.

Standard display

Front panel keys

V-set Choose constant voltage mode.
I-set Choose constant current mode.

P-set Choose constant power mode.
R-set Choose constant resistance mode.

Set the current mode's load value from the A value of the

Shift + A

corresponding transient operation. See the Transient
operation section. This key does not work when the

TRAN annunciator is on.

Set the current mode's load value from the B value of the

Shift + B

corresponding transient operation. See the Transient
operation section. This key does not work when the

TRAN annunciator is on.

Shift + Store

8500 DC Load Series Version: 032218 Page 9 of 76

Shift + Recall

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Store the DC Load state in non-volatile memory. You may
store 25 different states.

Recall the DC Load state from non-volatile memory. You
may recall 25 different states.

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Shift + Menu Enter the instrument's menu system.

4

1

23

1

2

3

Shift + Short Turn short circuit on or off.

Shift + Tran Start or stop transient condition.
Shift + Trigger Causes an immediate trigger.

Shift + Battery

Shift + S-Tran Set transient condition parameters.

On/Off

Shift

△ Scroll up key.
▽ Scroll down key.

0 to 9 Enter the digits 0 to 9.

• Decimal point.

Esc

Enter Enter the selected value or setting.

Turn on or off battery testing function (measures battery
capacity in ampere*hours).

Turns DC Load ON or OFF (OFF is high impedance
state).

The shift key is used to select the alternate operation of a
key, indicated by the word under the key.

The escape key. It can be used to exit keyboard entry or
move up a level in the menu.

Rear panel

Your instrument's rear panel may look different from the following figure, but the same functionality

will be present.

3 pin IEC320 AC input connector.
4 pin trigger and remote sensing connector.
9-Pin serial port interface connector. NOTE: This port's terminals utilize 5 volt

TTL logic signals. Do NOT connect an RS-232 cable with standard RS-232
voltages on the cables connectors. Doing so may damage the instrument and is

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not covered by warranty.

4

Line voltage selection switch (110 VAC or *220 VAC)
*For models 8524 and 8526, the line voltage switch is not usable and does not
allow for 220VAC operation. Do not connect them directly into a 220V line. For
220V operation, please order model 8524-220V or 8526-220V.

Power Requirements

All of the models, except for models 8524 and 8526, can accept 110V or 220V line input. To switch
between the two line voltage inputs:

1. Verify and change the fuse inside the fuse box beneath the AC input receptacle. See fuse

section for reference to the fuse type and rating.

2. Flip the 110V/220V line selection switch in the rear panel of the instrument.

WARNING:

Models 8524 and 8526 are configured for 110 V operation only. These two models are not
configurable via the line switch on the rear panel. Connecting an AC line input of a 8524 and
8526 to a 220V AC source will damage the units. If 220 V operation is desired, order model 8524­220V or 8526-220V. “-220V” denotes 220 V operation only, reconfiguration to 110 V is not
possible.

Display annunciators

Annunciator Meaning

OFF The load is off.

UNREG The input is unregulated.

CC Constant current mode.
CV Constant voltage mode.

CW Constant power mode.

CR Constant resistance mode.
PROT Not used.
TRAN Transient operation is enabled.

LIST List mode is initiated or running.

SENSE Remote sensing is on.

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Annunciator Meaning

LIMIT Not used.

ERROR An error has occurred.

The instrument is communicating with an IT-E132B communications

LINK

RMT

SHIFT The Shift key has been pressed.
LOCK The keyboard is locked by a password.

adapter. This annunciator will stay lit for approximately 3 seconds
after the last remote communication with the DC Load.

Instrument is in the remote state. The only active key is the Local
key. This is set with the 0x20 remote command (see the Remote
programming section).

Menus

Use Shift + 0 (Menu is secondary function) to enter the menus. “Lvl” indicates the menu level,
which is also indicated by the indentation of the menu item text. Scroll through the menu items
using the △ and ▽ keys. Return to a previous menu level by pressing the Esc key. Words in the

heavy font such as OFF indicate the default menu selection.

Lvl Menu item Function

1 CONFIG
2 INITIAL CONFIG Return instrument to factory default settings.
2 POWER-ON RECALL Power on state of instrument.
3 ON Remembers state at last power-down.

3

2 INPUT RECALL Remember whether load was ON

3 ON

3

2 KEY SOUND SET

3

3 OFF No sound when key is pressed.
2 KNOB LOCK SET
3 ON Rotary knob is non-functional.

3

2 SHORT CUT RECALL

3 ON

3

2 RANGE SELECT Change the precision of displayed values.
3 ON Allows the user to select the instrument's range, giving

OFF

OFF

ON

OFF

OFF

Does not remember state at last power-down.

If load was ON prior to turning the power off, the ON
state will be resumed after power on. POWER-ON
RECALL must also be on for this to work.

After power on, the instrument will be in the OFF state.

Enable audible beep when key is pressed.

Rotary knob is functional.

Quickly recall a setup register by pressing a number
key.

Allows quick recall of a setup by pressing the number
key.

Pressing a number key does not recall a setup.

better voltage and/or current resolution. Press Shift + △

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Lvl Menu item Function

or Shift + ▽ to toggle resolutions.

3

2 REMOTE SENSE See the Remote sense section.
3 ON Remote sensing is on.

3

2 ADC UPDATE RATE Set the rate at which the display is updated.
3 HIGH

3

2 TRIGGER SOURCE How the instrument is triggered.

3

3 EXTERNAL

3 BUS Triggered from a serial bus command.
2 CONNECT MODE

3 MAXTIPLEXING

3

2 BAUDRATE SET Set the serial bus connection speed.

3

3 9600
3 19200
3 38400
2 COMM. PARITY SET Serial connection parity.

OFF

OFF

LOW

IMMEDIATE

SEPARATE

4800

Current and voltage measurement resolution are fixed.

Remote sensing is off.

Triggered from the Shift + Trigger key.

Triggered from a TTL high signal (longer than 5 ms) at
the trigger connector on rear panel.

Not supported with this hardware. (Should actually say
"multiplexing".)

3

3 EVEN
3 ODD

2 ADDRESS SET

2 KEY LOCK SET

2 EXIT Return to prior menu level.
1 SYSTEM SET

2 MAX CURRENT SET

2 MAX POWER SET

8500 DC Load Series Version: 032218 Page 13 of 76

NONE

Set the instrument's address. Must be an integer
between 0x00 and 0xFE inclusive.

Set the instrument's password to 1 - 4 digits. Press the
Enter key without any data entry to remove the
password. If you accidentally locked the keyboard,
follow instructions at the end of this manual, chapter “in
case of trouble” to unlock the keypads.

Set the maximum allowed current. Exceeding this
value will cause the load to shut off. This value also
becomes the maximum current you can set.

Set the maximum allowed power. Exceeding this value
will cause the load to shut off. This value also becomes
the maximum power you can set.

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Lvl Menu item Function

Set the maximum allowed voltage. Exceeding this

2 MAX VOLTAGE SET

2 VOLTAGE ON SET

2 VOLTAGE OFF SET

2 EXIT Return to prior menu level.
1 LIST SET Lists are programmed sequences of load values.
2 MODE SET
3 FIXED MODE Load characteristics set by front panel.

3 LIST MODE

2 CALL LIST FILE Recall an existing list from nonvolatile memory.
3 RECALL N N is list number.

2 EDIT LIST FILE

3 CURRENT LIST
4 ONCE List is executed once per trigger.
4 REPEAT List is repeatedly executed after the trigger is received.
3 VOLTAGE LIST
4 ONCE List is executed once per trigger.
4 REPEAT List is repeatedly executed after the trigger is received.
3 POWER LIST
4 ONCE List is executed once per trigger.
4 REPEAT List is repeatedly executed after the trigger is received.
3 RESISTANCE LIST
4 ONCE List is executed once per trigger.
4 REPEAT List is repeatedly executed after the trigger is received.
2 CALL TEST FILE Recalls a stored test file (see Test files section).
3 RECALL N N is file number.
2 EDIT TEST FILE See Test files section for more details.

2 LIST STORE MODE

3 8 X 120 STEPS
3 4 X 250 STEPS
3 2 X 500 STEPS
3 1 X 1000 STEPS
2 EXIT Return to prior menu level.
1 LOAD ON TIMER Enable a timed load.
2 TIMER STATE

value will cause the load to shut off. This value also
becomes the maximum voltage you can set.

Used to set an ON voltage threshold. See the Voltage
threshold section. Default: 0.00 V

Used to set an OFF voltage threshold. See the
Voltage threshold section. Default: 0.00 V

Load characteristics are dynamic and controlled by a
list stored in memory.

Note that each list file has four lists, one for each
operation mode (CC, CV, CW, CR).

Set how the nonvolatile memory is partitioned to store
lists. You can choose between numerous short lists or
fewer longer lists.

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Lvl Menu item Function

When the load timer is enabled by this menu element,

3 ON

3

2 TIMER SET

2 EXIT Return to prior menu level.
1 EXIT Return to standard display.

OFF

the load is turned on when the On/Off key is pressed.
After the set time period has elapsed, the load is turned
off.

When the load is turned on via the On/Off key, the load
stays ON indefinitely.

Set the time period from 1 to 60000 s for the load to be
on.

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Models 8500 & 8502 (300 W)

Parameter 8500 8502

Voltage 0 – 120 V 0 – 500 V

Input rating

Parameter Range

CV Mode

Regulation

CC Mode

Regulation

Current Measurement

Voltage Measurement

Current 0 – 30 A 0 – 15 A

Power 300 W

8500 8502

0.1 – 120 V 0.1 – 500 V ±(0.05%+0.025% FS) 10 mV
0 – 3 A 0 – 3 A ±(0.1%+0.1% FS) 0.1 mA

0 – 30 A 0 – 15 A ±(0.2%+0.15% FS) 1 mA

0 – 3 A 0 – 3 A ±(0.1% + 0.1% FS) 0.1 mA

0 – 30 A 0 – 15 A

0-120 V 0 – 500 V ±(0.02% + 0.025% FS) 10 mV

Specifications

8500/8502 common characteristics

Accuracy Resolution

0.1-18 V ±(0.05%+0.02% FS) 1 mV

8500: ±(0.2%+0.15% FS)
8502: ±(0.2%+0.3% FS)

0-18 V ±(0.02% + 0.02% FS) 1 mV

1 mA

Models 8510/8512/8514/8518 (1200 & 2400 W)

Parameter 8510 8512 8514 8518

Voltage 0 – 120 V 0 – 500 V 0 – 120 V 0 – 60 V

Input rating

Parameter

CV Mode

Regulation

CC Mode

Regulation

Current Measurement

Voltage Measurement

Current 0 – 120 A 0 – 30 A 0 – 240 A 0 – 240 A

Power 600 W 1200 W

8510/8512/8514/8518 common characteristics

Range

8510 8512 8514 8518

0.1-18 V ±(0.05%+0.02% FS) 1 mV

0.1 V to Vmax ±(0.05%+0.025% FS) 10 mV

0-12 A 0-3 A 0-24 A ±(0.1%+0.1% FS) 1 mA

0 – max Current ±(0.2%+0.15% FS) 10 mA

0-12 A 0-3 A 0-24 A ±(0.1% + 0.1% FS) 1 mA

0 – max. Current ±(0.2%+0.15% FS) 10 mA

0 – 18 V

0 - Vmax ±(0.02% + 0.025% FS) 10 mV

Accuracy Resolution

8510/8514:
(0.02% + 0.025% FS)
8512/8518:
(0.02% + 0.02% FS)

1 mV

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Models 8520/8522/8524/8526 (2400W & 5000W)

Parameter 8520 8522 8524 8526

Voltage 0 – 120 V 0 – 500 V 0 – 60 V 0 – 500 V

Input rating

Parameter

CV Mode

Regulation

CC Mode

Regulation

Current Measurement

Voltage Measurement

Current 0 – 240 A 0 – 120 A 0 – 240 A 0 – 120 A

Power 2400 W 5000 W

8520/8522/8524/8526 common characteristics

Range

8520 8522 8524 8526

0.1-18 V ±(0.05%+0.02% FS) 1 mV

0.1 V to Vmax ±(0.05%+0.025% FS) 10 mV

0-24 A 0-12 A 0-24 A 0-12 A ±(0.1%+0.1% FS) 1 mA

0 – max Current ±(0.2%+0.15% FS) 10 mA

0-24 A 0-12 A 0-24 A 0-12 A ±(0.1% + 0.1% FS) 1 mA

0 – max. Current ±(0.2%+0.15% FS) 10 mA

0 – 18 V

0 - Vmax ±(0.02% + 0.025%FS) 10 mV

All DC load models

common characteristics for all DC load models

Parameter Range Accuracy Resolution

CR Mode Regulation
Input current ≥FS 10%
Input Voltage≥FS 10%

CW Mode Regulation
Input current ≥FS 10%
Input Voltage≥FS 10%

Power Measurement

Input current ≥ FS 10%

Input Voltage ≥ FS 10%

Battery testing function

Transition Mode

Range of Frequency 0.1 Hz-1 kHz Frequency error rate＜0.5%

0.1 -10 Ω ±(1%+0.3% FS) 0.001 Ω
10-99 Ω ±(1%+0.3% FS) 0.01 Ω

100-999 Ω ±(1%+0.3% FS) 0. 1 Ω

1K-4 KΩ ±(1%+0.8% FS) 1 Ω

0-100 W ±(1%+0.1% FS) 1 mW

100 W – max Power ±(1%+0.1% FS) 100 mW

0-100 W ±(1%+0.1% FS) 1 mW

100-max Power ±(1%+0.1% FS) 100 mW

Input=0.1 V – 120 V Max measurement capacity= 999 A/H

Resolution =10 mA Timer range=1~60000 sec

Accuracy Resolution

8522/8526:
(0.02% + 0.02% FS)
8520/8524:
(0.02% + 0.025% FS)

1 mV

NOTE: Specifications and information are subject to change without notice. Please visit
www.bkprecision.com for the most current product information.

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Environmental Conditions

This instrument is intended for indoor use in a pollution degree 2 environment. Operating
environmental limits are as follows:

Parameter Specification

Humidity ≤ 95% relative humidity, non-condensing

Altitude ≤ 2000 m

AC Input

*220 ACV ± 10%，47～63 Hz

110 ACV ± 10%，47～63 Hz

Operating temperature

Storage temperature

*For 220V operation on models 8524 and 8526, please order model 8524-220V and 8526-220V
respectively.

0 – 40 ºC

-10 – 60 ºC

Internal Resistances

The internal resistances of the DC load models are less than or equal to the following values:

Model Internal

Resistance(mΩ)

8500 ≤ 35

8502 ≤ 200

8510 ≤ 15

8512 ≤ 100

8514 ≤ 8

8518 ≤ 5

8520 ≤ 45

8522

8524 ≤ 6.5

8526 ≤ 15

8500 DC Load Series Version: 032218 Page 18 of 76

≤ 30

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Operational power curve

The DC load's output follows a power curve illustrated below:

The curved portion is where the dissipated power is at the rated power of the instrument (and is
actually a hyperbolic shape). When you use the menu to set lower-than-maximum power or current,
the operating region may look like the following:

Note the gap between the operating region and the current axis for lower voltages. More detail is
described in the following section.

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Low Voltage Characteristics

The following graphs show the voltage/current relationships for low voltages:

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Slew rate

The slew rate for each DC load varies from model to model. The variations are also dependent on
the different regions measured for each individual load. In general, the slew rate for low current
transitions, say 0 to 0.5 A, is significantly lower than slew rate for current transitions from 30 to 70 A.
The provided table below indicates measured slew rates based on the maximum range of current
transition of the models are capable of. For example, model 8500's slew rate would be measured
with current transition from 0 A to 30 A.

Note: The graph below illustrates slew rate measurements. In general, the indicated slew rates in
the table below are measured based on the maximum current range each model is able to handle.
Between the 10% and 90% region, the slew rate can be measured by observing the steepest slope
portion. The indicated measured time would be used to calculate the slew rate. Hence, the slew
rate calculation is simply (rated max. current – 0 A) / T, where T is the measured time from 10% to
90% region and rated max. current is the specified maximum current of each load.

8500 DC Load Series Version: 032218 Page 21 of 76

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As a reference, below is a table of slew rates for their respective models:

0.5A /  S

0.5A /  S

1A/  S

0.5A /  S

1A/  S

1A/  S

1A/  S

1A/  S

1A/  S

1A/  S

Model Slew rate

8500

8502

8510

8512

8514

8518

8520

8522

8524

8526

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Glossary

△ Up arrow key. Used to scroll through the menu or cause the temporary

display of the alternate standard display.

▽ Down arrow key. Used to scroll through the menu or cause the temporary

display of the alternate standard display.

A Value for first setting of transient mode.

B Value for second setting of transient mode.

Battery Select battery testing mode. See Battery test section.

CC Constant current

Condition Steady state, transient, or dynamic. Steady state condition means the

load mode is operated in a steady state. Transient condition means the
load mode is switched between two values with user-selectable timing.
Dynamic means multiple levels and timings are available (and are gotten
by using lists).

CR Constant resistance

CV Constant voltage

CW Constant power

Dynamic condition See Condition.

Enter Choose the indicated value or setting.

Esc Stop current entry and go to previous menu level.

I-set Configure the instrument for constant current mode.

Knob click Press the knob in until it clicks. This is an alternate method for changing

settings.

Link This annunciator will light up when communications are coming in across

the serial interface. It will stay lit for approximately 3 seconds after the
last command was received.

List A list is a stored sequence of test parameter and test duration values.

These are used for dynamic load profiles.

Local Returns control to the front panel.

Menu Show the top level item of the instrument's menus.

Mode Mode of operation of the instrument. The four modes are CC, CV, CW,

and CR.

Mode settings Parameter values for CC, CV, CW, and CR modes.

On/Off Manually toggle the instrument between its set mode and an infinite

impedance state.

P-set Configure the instrument for constant power mode.

Power Power switch to turn the instrument on and off.

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R-set Configure the instrument for constant resistance mode.

Recall Recall instrument state from non-volatile memory.

Remote sensing Allows the instrument to measure the load power properly in case of large

currents by sensing the voltage at the source, rather than at the
instrument's terminals. This removes the effect of the resistance of long
leads.

S-Tran Set parameters (A, B, and transition times) for transient mode.

Shift Shift key, which allows access to the functions written beneath the

number keys.

Short Toggles between normal operation and a low resistance short.

Store Allows the user to save the instrument state in non-volatile memory.

Test file A sequence of different test modes used for automated testing.

Tran Set to transient condition.

Transient condition See Condition.

Trigger The key that causes an immediate trigger.

V-set Configure the instrument for constant voltage mode.

VFD Vacuum fluorescent display, the technology used for the instrument's

display.

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Installation

CAUTION

Inspection

Items you should have received

When you open the box containing the instrument, you should find the following items:

1. The DC Load instrument

2. Power cord

3. User manual

4. Installation CD with application software PV8500

5. TTL to USB converter

6. Calibration report

Instrument location

This instrument is intended for indoor use in a pollution degree 2 environment. Please refer to the
specifications table for the allowable environment operating limits.

Significant power may be dissipated in the DC Load, which includes one or more thermostatically­operated fans. The fans draw air through the bottom and sides and exhaust it out the back. It is
important to allow at least 25 mm (1 inch) of clearance on all sides of the instrument so adequate
cooling airflow can be maintained.

Outline Drawings

All dimensions are in millimeters (mm).

Models: 8500& 8502

Do not block the fan exhaust at the rear of the load.

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Models 8510, 8512, 8514 & 8518

Models 8520, 8522

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Models 8524 & 8526

Unit (mm)

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Model number Dimensions in mm Mass in kg

8500 215W×88H×359D 5.2

8502 215W×88H×359D 5.2

8510 439.6W×88H×459D 14

8512 439.6W×88H×459D 14

8514 439.6W×88H×459D 14

8518 439.6W×88H×459D 14

8520 448W×185H×538.2D 30

8522 448W×185H×538.2D 30

8524 445.5W×357H×532D 67

8526 445.5W×357H×532D 67

Bench operation

The 8500 DC Load is provided with a carrying handle. The following pictures demonstrate various
ways to use the handle.

The handle may be removed if desired. A rack mounting kit (IT-E151) is also available for models
8500, 8502, 8510, 8512, 8514, and 8518.

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First turn-on checkout

CAUTION

Ensure that the line voltage selector switch on the
back panel is set to match your line voltage. Failure
to do so could result in damage to the instrument.

Note: For models 8524 and 8526, the line voltage
switch is not usable and does not allow for
220VAC operation. Do not connect them directly
into a 220V line. For 220V operation, please order
model 8524-220V or 8526-220V.

Connect an appropriate IEC power cord to the DC Load and plug the power cord into an AC power
outlet. Ensure that nothing is connected to the INPUT terminals. Turn the instrument on by pushing
the Power button in. The instrument should display SYSTEM SELFTEST, then display

0.00V 0.000A. A small annunciator will display OFF in the upper left corner of the display. If you

do not see this display, please consult the In case of trouble chapter.

The following test will verify the DC Load can operate properly in constant current mode. Press the
I-set button (you may have to press it twice) and use the numeric keypad to set the current to 0.1 A.
To do this, press . (the decimal point), 1, Enter. Alternatively, you can adjust the current level with
the knob, then click the knob or press Enter.

Connect a power supply or battery to the DC Load, observing the polarity. Turn the power supply on
and set a voltage of 1 volt. On the DC Load, press the On/Off button. You should see
approximately 0.1 A of current flowing as shown by the instrument's ammeter and approximately 1
volt. The CC annunciator should be displayed, showing that the instrument is in the constant current
mode.

The instrument's voltage display may read a bit less than the power supply's output -- this may be
due to a voltage drop in the wires connecting the power supply to the DC Load. Press the or △ ▽
keys to see the power that is being consumed by the load.

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Press the V-set button (you may have to press it twice). Note the load is turned off. Set the power
supply to 10V and the supply's current to a very low level, e.g. 0.1 A. Set the DC Load voltage level
well below the supply voltage level, e.g. 1 V. Press the On/Off key. Verify the proper voltage level
(1 V) is shown on the display. Press the △ or ▽ keys to see the power being dissipated.

Press the P-set button (you may have to press it twice). Note the load is turned off. Set the power
level to 0.1 watt. Press the On/Off key. Press the △ or ▽ keys to verify that the power is about 0.1
watt.

Press the R-set button (you may have to press it twice). Set the resistance to 100 . Press the
On/Off key. Verify that the current is approximately the displayed voltage in V divided by 100.

You can cycle between the four modes by pressing the I-set, V-set, P-set, and R-set buttons. Note
that the previously-set values are remembered.

If the instrument worked as explained above, you've demonstrated that the four operating modes of
the instrument are working. Please refer to the next section for detailed operation instructions.

Operational introduction

There are four operational modes of the instrument: constant current, constant voltage, constant
power, and constant resistance (we will abbreviate these as CC, CV, CW, and CR, respectively).
These are selected by the I-set, V-set, P-set, and R-set buttons, respectively. If you press a mode
button different than the currently set mode, the load will be set to OFF and the newly selected
mode's setting will be displayed for about 3 seconds. Pressing the same mode button again will
prompt for the new constant value for the selected mode.

There are three operational conditions for the instrument in these modes: steady state, transient,
and dynamic.

Condition Behavior

The selected mode parameter is maintained at a constant value. For example,

Steady state

Transient

Dynamic

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if you selected constant current mode and set the current value to 1 A, the
instrument would maintain this current indefinitely when the load is ON.

There are two mode parameters and the load switches between these two
settings with user-specified timing. An example of a transient load in constant
resistance mode would be a load of 10 Ω for 1 second and 20 Ω for 3 seconds.

Similar to the transient condition, but capable of emulating more complex time­dependent loads. The dynamic condition uses lists to specify the time­dependent behavior.

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Examples of the three conditions of operation are illustrated in the following diagram:

Steady state

Transient

Dynamic

A

B

Repeat

Time

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Power-on state

The default power-on instrument state is to not remember the instrument mode settings before the
last power-down. If you wish to have the mode settings remembered across a power-down, power­up cycle, use the following keystrokes:

8500 DC Load Series Version: 032218 Page 31 of 76

Key Display

Shift + Menu :CONFIG
Enter :INITIAL CONFIG

▽ :INPUT RECALL
▽ :POWER-ON RECALL

Enter :OFF <DEFAULT>

▽ :ON

Enter :POWER-ON RECALL
Esc :CONFIG

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Key Display

Esc Standard voltage/current display

Constant current mode

In constant current mode, the DC load will sink a constant current, regardless of the voltage at its
terminals. To set up the DC Load to operate in constant current mode and in the steady state
condition, use the following keystrokes:

Key Display

I-set If you press this key after powering up and there is no currently-

stored constant current value, you'll be prompted for the desired
current level. If there was a current value already stored, it will be
momentarily displayed and the instrument will be in CC mode. If
you wish to change the current setting, press I-set again. The OFF
annunciator will be displayed.

On/Off Turns the constant current load on. The CC annunciator will be on.

or △ ▽ Momentarily display the power level and the set current value.

On/Off Turns the load off.

To operate the DC Load in CC mode in a transient condition, see the Transient operation section.
To operate the DC Load in CC mode in a dynamic condition, see the Lists section.

Constant voltage mode

In constant voltage mode, the DC load will cause a constant voltage to appear at its terminals. To
set up the DC Load to operate in constant voltage mode and in the steady state condition, use the
following keystrokes:

Key Display

V-set If you press this key after powering up and there is no currently-

stored constant voltage value, you'll be prompted for the desired
voltage level. If there was a voltage value already stored, it will be
momentarily displayed and the instrument will be in CV mode. If
you wish to change the voltage setting, press V-set again. The

OFF annunciator will be displayed.

On/Off Turns the constant voltage load on. The CV annunciator will be

on.

or △ ▽ Momentarily display the power level and the set voltage value.

On/Off Turns the load off.

To operate the DC Load in CV mode in a transient condition, see the Transient operation section.
To operate the DC Load in CV mode in a dynamic condition, see the Lists section.

Constant power mode

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In constant power mode, the DC load will cause a constant power to be dissipated in the load. To
set up the DC Load to operate in constant power mode and in the steady state condition, use the
following keystrokes:

Key Display

P-set If you press this key after powering up and there is no currently-

stored constant power value, you'll be prompted for the desired
power level. If there was a power value already stored, it will be
momentarily displayed and the instrument will be in CW mode. If
you wish to change the power setting, press P-set again. The OFF
annunciator will be displayed.

On/Off Turns the constant power load on. The CW annunciator will be on.

or △ ▽ Momentarily display the power level and the set power value.

On/Off Turns the load off.

To operate the DC Load in CW mode in a transient condition, see the Transient operation section.
To operate the DC Load in CW mode in a dynamic condition, see the Lists section.

Constant resistance mode

In constant resistance mode, the DC load will behave as a fixed resistance value. To set up the DC
Load to operate in constant resistance mode and in the steady state condition, use the following
keystrokes:

Key Display

R-set If you press this key after powering up and there is no currently-

stored constant resistance value, you'll be prompted for the desired
resistance. If there was a resistance value already stored, it will be
momentarily displayed and the instrument will be in CR mode. If
you wish to change the resistance setting, press R-set again. The

OFF annunciator will be displayed.

On/Off Turns the constant resistance load on. The CR annunciator will be

on.

or △ ▽ Momentarily display the power level and the set resistance value.

On/Off Turns the load off.

To operate the DC Load in CR mode in a transient condition, see the Transient operation section.
To operate the DC Load in CR mode in a dynamic condition, see the Lists section.

Timed operation

The DC Load can be set to allow timed operation. When you turn the load on, it stays on for the
specified time, then turns itself off.

To set up timed operation, use the following keystrokes:

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Key Display

Shift + Menu :CONFIG

△ △ :LOAD ON TIMER

Enter :TIMER STATE

Enter Use arrow keys to set to :ON.

▽ :TIMER SET

Enter TIMER=XXXXXS Enter desired time interval. Valid values are

1 to 60000 seconds (1000 minutes).

Enter :TIMER SET

Esc Esc Standard display

Now, when you turn a load on, it will stay on for the designated time, then turn off.

To turn off timed operation, enter the menu :CONFIG:LOAD ON TIMER:TIMER STATE and set it to

:OFF.

Changing display resolution

The DC Load has two ranges of current and voltage (see the specifications). You can enable higher
resolution for voltages and currents on the lower range. Enter the menu with Shift + Menu and set
the menu element :CONFIG:RANGE SELECT to ON.

Increasing current resolution

To increase the current resolution (and change to the lower range), press Shift + . If the ▽ DC Load is
sinking a current higher than the top end of the lower range, it will be reset to the top end of the
lower range. To change back to the lower current resolution, press Shift + ▽ again.

Increasing voltage resolution

To increase the voltage resolution (and change to the lower range), press Shift + . You may see △

OVERVOLTAGE message on the display if the voltage is too high. To change back to the lower

voltage resolution, press Shift + △ again.

Short

When a test mode is on, you may press Shift + Short to emulate a short. This will draw maximum
current from the DC supply in any of the four operation modes (CC, CV, CW, or CR). In CC, CV, or
CR mode, you may press Shift + Short to stop the short. The DC Load will return to its previous
operation. However, in CW mode, the short current will continue to be drawn; to stop the short, you
must press the On/Off key

Note: When emulating a Short while in CV mode, the current software limit may trigger the DC load
Input to turn Off, provided the current limit is reached. This does not affect the programmed settings
and the DC load will restore the previously programmed values once the Short condition is removed.

Battery test

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The battery test feature measures the time it takes for a battery voltage to drop to a specified value

10A

5A

Continuous Transient Operation

2.0ms 3.0ms

while drawing a constant current from the battery. When the voltage at the DC Load's terminals
reaches the specified voltage, the test is ended and the integrated current (i.e., charge supplied by
the battery) in ampere*hours (A*hrs) of the battery is calculated and displayed. To run a battery test,
follow these steps:

Key presses Display

I-set, enter current value with

numerical keys, then press
Enter.

Set the DC Load to constant current mode and set the
current you want to draw from the battery. (You may have
to press the I-set key twice to be able to set the current
value.)

Shift + Battery MIN VOLT= 0.10V This indicates you're being asked for the

voltage level where the battery test will be over.

Enter voltage level and press
Enter.

When you press Enter, the test will start. The CC
annunciator will be on.

△ or ▽ Shows the power level and the ampere*hours (A*hrs)

accumulated so far.

When the battery voltage drops below the specified value, the test will turn off and you will see
the OFF annunciator.

△ or ▽ Display the total charge delivered by the battery in

ampere*hours (A*hrs).

Shift + Battery Turns battery testing mode off.

NOTE: you must make sure that you press Shift + Battery at the end of the test. Otherwise, the
instrument will not respond to any key presses except △ or ▽.

Transient operation

The transient condition allows switching between two different load values. There are three different
types of transient operation.

Continuous transient operation

In continuous transient operation, the load is continuously switched between two load values. An
example is shown in the following figure:

Note that this transient behavior works with any of the operation modes CC, CV, CW, or CR. Here
are the keystrokes used to setup this continuous transient condition:

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Keys Display

10A

5A

Pulsed Transient Operation

10ms

TWD

10ms

TWD

TRIG TRIG

I-set Standard display of voltage and current (or, you'll be asked to enter a

current value).

Shift + S-Tran LEVEL A= X.XXXA You are being prompted for the first current value.

Press the 5 key for 5 A.

Enter Enters the 5 A value, then displays WIDTH A = X.XMS. You're being

prompted for the duration of the 5 A load -- press the 3 key for 3 ms.

Enter Enters the 3 ms value, then displays LEVEL B= X.XXXA. You are being

prompted for the second current value. Press the 1 and 0 keys to enter
10 A.

Enter Enters the 10 A value, then displays WIDTH B = X.XMS. You're being

prompted for the duration of the 10 A load -- press the 2 key for 2 ms.

Enter Enters the 2 ms duration, then displays :CONTINUOUS, :PULSE, or

:TOGGLED. Use the △ or ▽ arrow keys to display :CONTINUOUS.

Enter Returns to the standard display of voltage and current.

To activate this continuous transient condition, press Shift + Tran, then press On/Off. The load will
begin switching between the two Tran values with the timing you entered.

Pulse transient operation

In pulse transient operation, the load operates at the A value that has been entered until a trigger is
received. At the trigger, the load switches to the B value and stays at that level for the B timing
value. Then the load switches back to the A value and stays there until another trigger is received.
Here's an example:

Here are the keystrokes needed to set up this example:

Keys Display

I-set Standard display of voltage and current (or, you'll be asked to enter a

current value).

Shift + S-Tran LEVEL A= X.XXXA You are being prompted for the first current value.

Press the 5 key for 5 A.

Enter Enters the 5 A value, then displays WIDTH A = X.XMS. You're being

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8500 DC Load Series Version: 032218 Page 36 of 76

prompted for the duration of the 5 A load. In the pulse mode of operation,

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Keys Display

10A

5A

TRG

TRG

Toggled Transient Operation

this width is ignored, so enter any convenient value.

Enter Displays LEVEL B= X.XXXA. You are being prompted for the second

current value. Press the 1 and 0 keys to enter 10 A.

Enter Enters the 10 A value, then displays WIDTH B = X.XMS. You're being

prompted for the duration of the 10 A load -- press the 1 and 0 key for 10
ms.

Enter Enters the 10 ms duration, then displays :CONTINUOUS, :PULSE, or

:TOGGLED. Use the △ or ▽ arrow keys to display :PULSE.

Enter Returns to the standard display of voltage and current.

To activate this pulse transient condition, press Shift + Tran, then press On/Off. The load will start
at the A level of current you entered (5 A). Press Shift + Trigger to cause the load to switch to the
B level of current (10 A). The 10 A current will last for the designated 10 ms, then switch back to the
A level (5 A).

NOTE: This example requires the :CONFIG:TRIGGER menu item be set to :IMMEDIATE. If set
to :EXTERNAL, you'd trigger the instrument with a high TTL level signal on the trigger terminals on

the rear panel. If set to :BUS, you'd trigger the instrument with a software trigger.

Toggled transient operation

In toggled transient operation, the load starts at the stored parameter for the mode. When a trigger
is received, the load switches to the B value. When another trigger is received, the load switches to
the A value. It stays at the A value until another trigger is received, at which point it switches to the
B value. Further triggers cause the load to switch between the A and B values. Here's an example:

Here are the keystrokes needed to setup this example:

Keys Display

I-set Standard display of voltage and current. Enter a value of 5 A (you may

need to press the I-set key again). Press Enter.

Enter Enters the CC mode's value. The standard display is shown.

Shift + S-Tran LEVEL A= X.XXXA You are being prompted for the first current value.

Press the 5 key for 5 A.

Enter Enters the 5 A value, then displays WIDTH A = X.XMS. You're being

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Keys Display

prompted for the duration of the 5 A load. In the toggled mode of
operation, this width is ignored, so enter any convenient value.

Enter Displays LEVEL B= X.XXXA. You are being prompted for the second

current value. Press the 1 and 0 keys to enter 10 A.

Enter Enters the 10 A value, then displays WIDTH B = X.XMS. You're being

prompted for the duration of the 10 A load. . In the toggled mode of
operation, this width is ignored, so enter any convenient value

Enter Displays :CONTINUOUS, :PULSE, or :TOGGLED. Use the △ or ▽ arrow

keys to display :TOGGLED.

Enter Returns to the standard display of voltage and current.

To activate this toggled transient condition, press Shift + Tran, then press On/Off. The load will
start at the value you entered for A (5 A). Then press Shift + Trigger to cause the load to switch to
the B level of current (10 A). The next trigger will cause the load to shift back to the A level (5 A).
Subsequent triggers repeat this behavior.

NOTE: This example requires the :CONFIG:TRIGGER menu item be set to :IMMEDIATE. If set
to :EXTERNAL, you'd trigger the instrument with a high TTL level signal on the trigger terminals on

the rear panel. If set to :BUS, you'd trigger the instrument with a software trigger.

Toggle between two test values

When you have entered A and B values through the Shift + S-Tran menu, those values are
available to you at the front panel. Suppose you set the instrument to operate in CC mode at a
current of 1 A. If the transient A level was 5 A and the transient B level was 10 A, you can set the
instrument to the A level by pressing Shift + A. The load has to be on and cannot be in transient
condition (i.e., the TRAN annunciator must not be lit). Otherwise, the A value will be stored as the
CC mode's current. Similarly, Shift + B causes the B value to be stored as the CC mode's current.
The load can be on or off for this to work.

Lists (dynamic condition)

Transient operation is used for simple step changes in load values. More complicated dynamic
behavior of the load can be obtained through the use of lists. Lists are a sequence of load value and
duration pairs. Lists are the logical extension of transient operation.

Note: Resolution of the step values defined in list mode varies depending on the mode of
operation. In CW, CR, and CV list mode, resolution defined for each list step is maximum at
10 mW, 10 mΩ, and 10 mV respectively. For example, a CW list step can be configured as

10.23 W. For CC list mode, maximum resolution is 1 mA for the step values. For example, a
CC list step can be configured as 1.234 A.

To illustrate the use of a list, we'll create a list that runs the following constant current profile on a
power supply:

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Trigger

10 2 3 4 5

List count=1 List count=2

List sequence

This list is characterized by the following current/duration pairs

Current, A Duration, ms Between times

3 1000 0 and 1
0 800 1 and 2
2 500 2 and 3
0 300 3 and 4
6 500 4 and 5

This list has 5 steps, located at the transitions 1 through 5. The first duration, 1000 ms, occurs after
the triggered event. Subsequent durations are from the previous transition to the current transition.

Here are the keystrokes to set up this list:

Keys Display

Shift + Menu :CONFIG

▽ ▽ :LIST SET

Enter :MODE SET

Enter Select :LIST mode. This will cause the LIST annunciator to turn on.

Enter :MODE SET

▽ ▽ :EDIT LIST FILE

Enter :CURRENT LIST

Enter Select :REPEAT.

Enter LIST COUNT= N How many steps this list has. Enter the number 5.

5 Enter COUNT 1= X.XXA Set the current for the first step. Enter 3.

3 Enter COUNT 1= X.XXMS Set the duration for the first step. Enter 1000.

1000 Enter Repeat the current and duration entry for the following 4 steps.

Enter STORE LIST FILE1 The 1 is underlined, indicating you can enter a

number to specify the "file" (i.e., block of EEPROM) to store this list to.
Choose a number via the keypad or the knob. You can choose any
number between 1-8.

Enter :EDIT LIST FILE

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Keys Display

Esc Esc Standard display

First, press the On/Off key. The load will sink the current that is stored as the CC mode parameter
(set it to 0 A if you don't want an initial current). Then press Shift + Trigger to have the list start
executing.

Should you wish to have the list only execute once after the trigger, you can edit the list to use

:ONCE instead of :REPEAT.

To exit List mode press the Shift and Trigger key

Test files

Test files are a generalization of lists -- they let you generate a sequence of tests using different
modes, mode parameters, and durations. They are useful for executing a set of tests on a device,
then displaying whether the tests passed or failed. We will illustrate how to use test files by a short
example.

Suppose we have a small AC to DC power supply (a "wall-wart") and we want to set up an
acceptance test for a number of these devices. Our test will consist of two steps:

1. Set the DC load to constant current mode to draw the rated current of 0.35 A from the
device. The output voltage of the device at the rated current must be between 4.4 volts and

4.6 volts.

2. When the device operates into a short, the supplied current must be larger than 2.0 A.

Keys Display

Shift + Menu :CONFIG

▽ ▽ :LIST SET

Enter :MODE SET

▽ ▽ ▽ ▽ :EDIT TEST FILE

Enter MAX CURR= 3.000A Set the maximum current to 2.5 A

2.5 Enter MAX VOLT= 18.00V Set the maximum voltage to 5 V

5 Enter MAX POWER= 150.00W Set the maximum power to 15 W

15 Enter TEST COUNT= 6 Our test will consist of two steps, so we enter 2. You

can enter up to 20 steps.

2 Enter CONST CURRENT Since our first test is in constant current mode, we'll

just press Enter to select this mode.

Enter SET 1= 0.210A This is the prompt for the constant current value. We set

it to 0.35 A.

.35 Enter SHORT OFF We can turn a short on or off at this step. Here, we want

short off, so we just press Enter.

Enter READBACK V We're being prompted for what parameter to read back

and check. We want voltage, so we press Enter.

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Keys Display

Enter MIN 1= 5.80V We want the minimum voltage read back to be at least 4.4

V.

4.4 Enter MAX 1= 6.15V The maximum value we'll allow is 4.6 V.

4.6 Enter DELAY 1= 1.0<S> This delay time is how long to wait before making the

readback measurement. If you set it to 25.5 seconds, the test will halt at
this point, requiring you to press Shift + Trigger to continue the test. We'll
use 1 second.

1 Enter CONST CURRENT We're being prompted for the mode to use for the

next step. We'll again use constant current, so we'll press Enter (this step
will also be a short, so the mode doesn't really matter).

Enter SET 2= 5.000A We'll set the current to 2.5 A, which is the maximum

current we've allowed for this test..

2.5 Enter SHORT OFF We select short on and then press Enter.

Enter▽ READBACK A We want to readback the current, so we press Enter.

Enter MIN 2= 4.950A Our minimum value is 2.0 A.

2 Enter MAX 2= 5.050A We choose 2.5 A as the maximum value.

2.5 Enter DELAY 2= 3.0<S> We'll wait 2 seconds for the maximum current.

2 Enter STORE TEST FILE1 The 1 is underlined, meaning you can choose

which test file number to store this test to. You can choose any number
between 1-8. Here, we will use 1, so just press Enter.

Enter EDIT TEST FILE

Esc Esc Exit the menu. The normal display is shown (V and A).

The test file has been created and saved in file position 1. Now we will run the test on the device.

Keys Display

Shift + Menu :CONFIG

▽ ▽ :LIST SET

Enter :MODE SET

▽ ▽ ▽ :CALL TEST FILE

Enter RECALL 1 We're being prompted for which file number to recall. Since

we saved to file number 1, we just press Enter.

Enter CALL TEST FILE The test file is now loaded, so we return to the normal

display.

Esc Esc Exit the menu. The normal display is show (V and A).

Shift I-set NAME:TEST FILE 1 We've entered automatic testing mode. The display

is showing which test file we're using.

Shift Trigger This starts the test. You'll see the values sequentially displayed. Then

you'll either see PASS or FAULT. You can press Shift Trigger again for

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Keys Display

another test run or press Esc to return to the normal display.

Esc Return to the normal display.

Triggering

Triggering is used with the transient and dynamic conditions to allow synchronization of the DC
Load's behavior with other events. There are three types of triggers you may use (set in the

CONFIG:TRIGGER SOURCE menu):

Trigger Type Explanation

IMMEDIATE An immediate trigger is created by pressing Shift + Trigger on the

front panel keys.

EXTERNAL An external trigger is a TTL high signal applied to the Trigger

connection on the back panel. This TTL signal must last for more than
5 ms. A trigger applied to this input can be used to change settings
(voltage, current , resistance), toggle between settings in transient­toggle mode, or generate a pulse in pulse mode.

BUS The instrument will be triggered if a 5AH command is sent via the USB

(Virtual COM) interface. See the Remote operation section for more
details.

Voltage threshold operation

The DC Load can be set to only turn on if the voltage is at or above a set value. Additionally, the
load will turn off if the voltage drops below a second set value. This feature works for any mode.

Note: Voltage threshold operation has a minimum time requirement of 500 ms for it to detect
the set conditions and respond accordingly. Therefore, when operating in modes (i.e.
transient mode, list mode) in which timing between load changes can be set to < 500 ms, this
operation will not function.

An example of use would be to ensure an electronic system under test will not have power applied
unless the supply voltage is above a certain value. The DC Load would be put in series with the
power supply. Remote sensing would be turned on and the remote sensing connector on the back
would be used to connect to the power supply's output voltage.

Use the menu items SYSTEM SET:VOLTAGE ON SET and SYSTEM SET:VOLTAGE OFF SET to
set the on and off voltage thresholds, respectively.

Example 1: set the VOLTAGE ON SET and SYSTEM SET:VOLTAGE OFF SET both to 1.0 V.
Set the instrument to constant current mode with the I-set key and set the current level to 0.1 A.
Turn the load on by pressing the On/Off key. When power is applied to the DC Load, the voltage
must rise above 1.0 V before the load draws current from the source. If the voltage drops below 1.0
V on the load's terminals, the load will stop drawing current from the source.

Example 2: Same as the previous example, except set the VOLTAGE ON SET to 1.0 V and the
SYSTEM SET:VOLTAGE OFF SET 0.0 V. As before, the load will turn on only when the voltage
exceeds 1.0 V, but once it is "triggered" on, it will now stay on, even if the voltage drops to zero.

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Passwords

If you enter the menu CONFIG:KEY LOCK SET, you can set a one to four digit password. This
password will be required when changing settings from the front panel. The only operations allowed
without entering the password are:

Shift + A
Shift + B
Shift + Short
Shift + Tran
Shift + Trigger
On/Off

To remove the password, enter the menu CONFIG:KEY LOCK SET and do not press any number
keys, then press Enter.

Protection features

To protect external hardware when using the DC Load, you can set the maximum allowed values for
current, voltage, and power. These settings will override any settings subsequently made from the
front panel using the I-set, V-set, P-set, or R-set keys.

To set these protection values, use the following keystrokes:

Keys Display

Shift + Menu :CONFIG

▽ :SYSTEM SET

Enter Select between:

:MAX CURRENT SET
:MAX POWER SET
:MAX VOLTAGE SET

using the △ and ▽ arrow keys, then press Enter. Enter the desired value,
then press Enter to accept it.

Esc Esc Exit from the menu.

Example: Suppose you are measuring current vs. voltage characteristics of a 1 watt resistor. You
could set the maximum allowed power to 1.1 watts to test the resistor's rating, yet not go over the
maximum rating by more than 10% to ensure you don't destroy the resistor. If you tried to use the P-
set key to set the power to more than 1.1 W, the instrument will limit the set value to 1.1 W.

Over Voltage protection

If input voltage exceeds the voltage limit set by the user, the DC load will turn the input OFF and the
buzzer will sound. The display will show OVER VOLTAGE. The maximum voltage limit value is equal to

the maximum rated voltage for each model. For the over voltage protection state to be activated, the voltage
level presented to the load terminal must exceed the limit set value by approximately 5%.

Over Current protection

When operating in CR, CC or CW mode, the load current will be limited by a current limit value set
by the user. The maximum current limit value is equal to the maximum rated current for each model.

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Once the maximum current limit is reached, the DC Load will enter the over current protection state
and the current will be limited to the set value. (The input will not turn off). If the DC load previously
operated CR or CW mode, the DC load will automatically revert to CC mode and the VFD display
will indicate CC. When the DC load operates in a combined CV / transition mode or CV / List mode,
the buzzer will sound if the input current exceeds the current limit and the display will show a
flashing current value.

Over Power protection

If the input power exceeds the power limit in the normal operation mode, the DC load will enter the over power
protection state. The display will show CW.

If the input power exceeds the limit when in transition mode or list mode, the buzzer will sound and the
display will flash the current value and voltage value.

Reverse voltage protection

This feature protects the load module in case the DC input terminals are connected to a power source with
reversed polarity. If a reverse voltage condition is detected, the buzzer will sound and REVERSE VOLTAGE
will be displayed on screen.

Over Temperature protection

If internal temperature exceeds safety limits (80 ;176℃ °F), the Over temperature circuitry will be activated. The
DC Load will turn off the input, the buzzer will sound, and the display will show OVERHEAT.

Remote sensing

Remote sensing is used to counteract the effect of lead resistance. For example, if you connect a
power supply to the DC Load, the voltage at the power supply's terminals will not be the same as the
voltage at the DC Load's terminals if there is a current flowing because of the finite resistance from
the wires. Using remote sensing, you can sense the voltage at the power supply's terminals,
effectively removing the effect of the voltage drop in the connection wire.

When using remote sensing, the power displayed by the instrument includes both the power
dissipated inside the instrument and the power dissipated in the leads from the power supply to the
DC Load's input terminals.

To turn remote sensing on:

Keys Display

Shift + Menu :CONFIG

Enter :INITIAL CONFIG

▽ 8 times :REMOTE SENSE

Enter :OFF|DEFAULT|

▽ :ON

Enter :REMOTE SENSE and annunciator shows Sense.

Esc Esc Exit from the menu.

The following diagram shows the remote sensing terminals on the back of the instrument:

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The following shows a wiring diagram for remote sensing:

Example: A power supply is connected to the DC load with 72.5 cm of 20-gauge solid copper wires.
The constant current i set to 5 A. The power supply's output meter reads 27.0 V and the DC Load's
voltage display reads 26.71 V with a power dissipation of 133.70 W. This is without remote sensing
enabled. With remote sensing turned on and the remote sensing terminals connected to the power
supply output terminals, the DC Load reads 26.98 V and indicates 134.95 W of power dissipation.
This demonstrates that (134.95 - 133.70) = 1.25 W is dissipated in the 20-gauge wires. From the
resistance per unit length of 20-gauge wires, the expected dissipated power at 5 A can be calculated
as 1.21 W.

Saving and Recalling settings

The DC Load provides 25 non-volatile registers to save instrument settings for recall later.

To save the instrument's settings to a register, press Shift + Store. You'll be prompted for a register
number. Enter a number between 1 and 25, then press the Enter key. The settings are saved.
Note that this will overwrite any values previously saved in that register.

To recall the instrument's settings from a register, press Shift + Recall. You'll be prompted for a
register number. Enter a number between 1 and 25, then press the Enter key. The stored settings
are saved. Note that this will overwrite all values currently set in the instrument.

If you try to recall a register with no data in it, you will get a NO EEPROM DATA error message.

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Remote operation

WARNING

Communication cables

The DC Load has a DB9 connector on the rear panel that allows remote communication.

Do not connect the DC Load's DB9 connector to a standard RS-232
instrument. Doing so may damage the instrument, as the instrument
requires TTL logic signals, not standard RS-232 voltages.

Two adapters are available to perform the correct level shifting.

USB to TTL serial converter cable IT-E132B

The IT-E132B adapter allows you to talk to the DC load via your Windows® computer's USB
interface. To use this interface, you must install the software driver that came with the IT-E132B
adapter.

To install the driver, run the PL-2303 Driver Installer.exe file that comes on the CD. This will install
the driver . After installation, right click on My Computer and select Manage. Click on Device
Manager in the left-hand pane, then click on Ports in the right hand pane. You should see an entry
named Prolific USB-to-Serial Comm Port.

Once the driver software is installed on your system, it will appear as if you have a new COM port.
This COM port can then be accessed as if it were a regular RS-232 port.

The LEDs in the adapter will blink when information is being sent through the adapter. This is a
good way to tell if your communication link is active.

USB (Virtual COM) settings

In order for the computer to communicate with the DC Load, both must be set to the same serial
settings. These communication settings are:

1. Baud rate must be one of 4800, 9600, 19200, or 38400.

2. 8 data bits.

3. One stop bit.

4. No parity.

NOTE: DTR and RTS signal lines must be enabled/asserted.

Overview of DC Load programming

Packet structure

The DC Load is programmed using packets of bytes. A packet always contains 26 bytes, either
going to or coming from the instrument. The basic programming rule is:

You send a 26 byte packet to the instrument. You then
read a 26 byte packet back from the DC Load to either

● Get the status of your submitted packet, or

● Get the data you requested.

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The following are conventions we will follow in this chapter:

1. Hexadecimal integers will be represented by the prefix 0x.

2. Numbers are in base 10 number system unless otherwise indicated.

3. Byte numbering is zero-based, meaning numbering starts with 0.

The structure of each 26 byte packet is:

Byte 0 Byte 1 Byte 2 Byte 3 to 24 Byte 25

0xAA Address Command Command's data Checksum

Thus, the first byte of any command packet or returned packet is always 0xAA.

Address must be a byte that is between 0x00 and 0xFE. Setting of the address is optional. It is not
required to communicate with the instrument. The address can be set from the front panel and is
stored in non-volatile memory. This feature is useful when communicating via USB, and connecting
several instruments, e.g. via a USB hub. In this scenario, Windows assigns a virtual COM port to
each device which is unknown prior to establishing communications with the instrument (could be
different each time). In this case, the user can correlate each virtual COM port randomly assigned by
Windows with a user defined address.

Command is a byte that identifies which DC Load command is used.

The area for the command's data contains parameter information for the command or the data that
is requested via a previous command. Some commands have no data at all. It is a good
programming practice to set all unused bytes to 0x00.

The checksum number is the arithmetic sum of each of the bytes modulo 256.

Status packets

When you send a command that does not cause the DC Load to send requested information back to
you, you will receive a status packet back. The structure of a status packet is

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 to 24 Byte 25

0xAA Address 0x12 Status byte Reserved Checksum

The meaning of the return status byte is defined below:

0x90 Checksum incorrect

0xA0 Parameter incorrect

0xB0 Unrecognized command

0xC0 Invalid command

0x80 Command was successful

Even for commands that request for data to be read back, if the command is incorrect, the status
packet will also be received with one of the above status bytes.

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Example program

As you have seen, the native programming interface to the DC loads is fairly low-level. It involves
sending 26 byte commands and receiving 26 byte responses from the instrument. To demonstrate
how to write your own source code to remotely control the DC load, we provide a custom program
written in python which translates well into other text based languages like C/C++

About Python: Python is a dynamic object-oriented programming language that can be used for
various kinds of software development. It offers strong support for integration with other languages
and tools, comes with extensive standard libraries, and is easy to learn in a few days time. Python is
distributed under an OSI-approved open source license that makes it free to use.

You can download a complete python program along with detailed documentation from our website
at www.bkprecision.com. Also available under the download area is a high level library which will
make programming much easier as it does the low level bit manipulation for you. Instead of sending
a 26 byte string, you can send a high level command such as SetMaxCurrent(current)

Example script:

# Set DC load to remote mode.

import serial
length_packet = 26 # Number of bytes in a packet

def DumpCommand(bytes):
assert(len(bytes) == length_packet)
header = " "*3
print header,
for i in xrange(length_packet):
if i % 10 == 0 and i != 0:
print
print header,
if i % 5 == 0:
print " ",
s = "%02x" % ord(bytes[i])
if s == "00":
s = chr(250)*2
print s,
print

def CalculateChecksum(cmd):
assert((len(cmd) == length_packet - 1) or (len(cmd) ==
length_packet))
checksum = 0
for i in xrange(length_packet - 1):
checksum += ord(cmd[i])
checksum %= 256
return checksum

def main():
port = 3 # COM4 for my computer
baudrate = 38400
sp = serial.Serial(port, baudrate) # Open a serial connection
# Construct a set to remote command
cmd = chr(0xaa) + chr(0x00) + chr(0x20) # First three bytes

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cmd += chr(0x01) + chr(0x00)*(length_packet - 1 - 4)
cmd += chr(CalculateChecksum(cmd))
assert(len(cmd) == length_packet)

# Send command to DC load
sp.write(cmd)
print "Set to remote command:"
DumpCommand(cmd)

# Get response from DC load
response = sp.read(length_packet)
assert(len(response) == length_packet)
print "Response:"
DumpCommand(response)

main()

The first three lines of the main() function set up a serial port to talk to. The next five lines construct
the string that we will send to the DC load. The chr() function creates a single character that has
the ASCII value of the argument. The + symbols allow strings to be concatenated. The expression

chr(0)*a_number creates a string of ASCII 0x00 characters whose length is a_number. . The last

character is the checksum of the previous 25 characters, calculated for us by the

CalculateChecksum() function.

When a command is sent to the instrument, you must always request for return data, which will
always be another 26 bytes. This is also dumped to the screen.

Here are the printed results when the above script is ran:

Set to remote command:
aa ·· 20 01 ·· ·· ·· ·· ·· ··

·· ·· ·· ·· ·· ·· ·· ·· ·· ··

·· ·· ·· ·· ·· cb
Response:
aa ·· 12 80 ·· ·· ·· ·· ·· ··

·· ·· ·· ·· ·· ·· ·· ·· ·· ··

·· ·· ·· ·· ·· 3c

The · characters represent the bytes with a value of 0x00. This makes it easier to see the nonzero
bytes in the string.

The first byte of a command is always 0xaa and the second byte is the address of the DC load. The
address should be set to 0. The third byte identifies the command "set to remote" and the fourth
byte is a 1, which means enable remote mode. If the fourth byte was 0, this command would set the
DC load to local mode.

The third byte of the response string is 0x12, which means this is a packet that gives the status of
the last command sent. The fourth byte is 0x80, which means the command completed
successfully.

On the DC load, you should see the Rmt annunciator turned on immediately after running the script.

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You will also see the Link annunciator light up while communications are going on, then blink out
after a few seconds.

Press Shift + Local to set the DC load back to local mode.

We've learned two key things about the DC load:

1. Commands are always sent as 26 byte packets.

2. For any command you send to the DC load, you must also request the return of a 26 byte
packet. This returned packet will either be a status packet or an information packet
containing data you requested -- for example, the power level currently set.

Get in the habit of looking at the LEDs on the IT-E132B interfaces. Every command you send to the
DC load should result in both the RX and TX LEDs blinking once. If this does not happen,
something is wrong with the code, interface, or instrument.

Chapter organization

The remainder of this chapter contains a reference on the syntax of DC Load commands and some
example programs. The Summary of commands section is a list of the commands, but without
details. The Command details section explains how to use each command.

Summary of commands

The Byte values in the following table are used to identify the commands to be sent in the command
packet (byte 2).

Command Group Byte Action

Return data 0x12

Remote 0x20 Set the DC Load to remote operation

ON/OFF 0x21 Turn the load ON or OFF

0x22 Set the maximum voltage allowed

0x23 Read the maximum voltage allowed
Maximum parameter
values

0x24 Set the maximum current allowed

0x25 Read the maximum current allowed

0x26 Set the maximum power allowed

Indicates a packet that returns the status of the last command you
sent to the DC Load

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Command Group Byte Action

0x27 Read the maximum power allowed

Operation mode

Mode parameters

Transient
parameters

0x28 Set CC, CV, CW, or CR mode

0x29 Read the mode being used (CC, CV, CW, or CR)

0x2A Set CC mode current

0x2B Read CC mode current

0x2C Set CV mode voltage

0x2D Read CV mode voltage

0x2E Set CW mode power

0x2F Read CW mode power

0x30 Set CR mode resistance

0x31 Read CR mode resistance

0x32 Set CC mode transient current and timing

0x33 Read CC mode transient parameters

0x34 Set CV mode transient voltage and timing

0x35 Read CV mode transient parameters

0x36 Set CW mode transient power and timing

0x37 Read CW mode transient parameters

List operations

0x38 Set CR mode transient resistance and timing

0x39 Read CR mode transient parameters

0x3A Select the list operation (CC/CV/CW/CR)

0x3B Read the list operation (CC/CV/CW/CR)

0x3C Set how lists repeat (ONCE or REPEAT)

0x3D Read how lists repeat

0x3E Set the number of list steps

0x3F Read the number of list steps

0x40 Set one of the step's current and time values

0x41 Read one of the step's current and time values

0x42 Set one of the step's voltage and time values

0x43 Read one of the step's voltage and time values

0x44 Set one of the step's power and time values

0x45 Read one of the step's power and time values

0x46 Set one of the step's resistance and time values

0x47 Read one of the step's resistance and time values

0x48 Set the list file name

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Command Group Byte Action

0x49 Read the list file name

0x4A Set the memory partitioning for storing lists

0x4B Read the memory partitioning for storing list steps

0x4C Store the list file

0x4D Recall the list file

Battery testing

LOAD ON

Address 0x54 Set communication address

LOCAL 0x55 Enable/disable LOCAL control

Remote sensing

Triggering

Store/Recall

Function

0x4E Set minimum voltage in battery testing

0x4F Read minimum voltage in battery testing

0x50 Set timer value of for LOAD ON

0x51 Read timer value for LOAD ON

0x52 Disable/enable timer for LOAD ON

0x53 Read timer state for LOAD ON

0x56 Enable/disable remote sensing

0x57 Read the state of remote sensing

0x58 Select trigger source

0x59 Read trigger source

0x5A Trigger the electronic load

0x5B Store DC Load's settings

0x5C Recall DC Load's settings

0x5D Select FIXED/SHORT/TRAN/LIST/BATTERY function

0x5E Get function type (FIXED/SHORT/TRAN/LIST/BATTERY)

Read display values 0x5F Read input voltage, current, power and relative state

0x60 Enter instrument calibration state

0x61 Get the instrument calibration state

0x62 Set voltage calibration point index

0x63 Send the actual voltage to the calibration program

Calibration

Product information 0x6A Get product's model, serial number, and firmware version

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0x64 Set current calibration point index

0x65 Send the actual current to the calibration program

0x66 Store the calibration data to EEPROM

0x67 Set calibration information

0x68 Read calibration information

0x69 Restore the factory default calibration data

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Command Group Byte Action

0x6B Read the bar code information

Command details

In the following, please remember that the word mode only refers to one of the four operational
modes of the DC Load: constant current (CC), constant voltage (CV), constant power (CW), or
constant resistance (CR).

Notation for tables

In the following sections, we abbreviate the details of the commands. Since the first three bytes of a
command are i) the constant 0xAA, ii) the instrument address, and iii) the command, we will not
show those for each command. In addition, the 26th byte, the checksum, will also not be shown.

The table includes a column for Byte offset. This is the zero-based index of the byte in the packet.
Note the offset numbers are in decimal.

A table entry of “Reserved” means the data are currently unused or reserved for future use. Good
programming practice is to set these bytes to 0x00.

Some commands require two byte and four byte integers to represent parameter settings. These
integers are stored in the command packet in little-endian format. Little-endian is a byte ordering
format in which bytes with lower addresses have lower significance. We will refer to the individual
bytes as follows:

For a two byte integer, the least significant byte will be called the low byte and the most significant
byte will be called the high byte.

For a four byte integer, we will use the following notation:

Least significant two bytes, least significant byte Lower low byte
Least significant two bytes, most significant byte Lower high byte
Most significant two bytes, least significant byte Higher low byte
Most significant two bytes, most significant byte Higher high byte

As an example, for the integer 0x23A749F5, we'd have

1st byte 0xF5 Lower low byte
2nd byte 0x49 Lower high byte

3rd byte 0xA7 Higher low byte
4th byte 0x23 Higher high byte

0x12 Indicates a return packet for a command sent to the DC Load

Byte

offset

3 Status byte (i.e., status of last command sent to DC Load).

4-24 Reserved

Meaning

Below is a table of all possible status byte values and their corresponding indication.

0x90 Checksum incorrect

0xA0 Parameter incorrect

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0xB0 Unrecognized command

0xC0 Invalid command

0x80 Command was successful

0x20 Set the DC Load to remote operation

Byte

offset

3 0 means front panel operation.

1 means remote operation.

4-24 Reserved

Meaning

0x21 Turn the load ON or OFF

Byte

offset

3 0 is OFF.

1 is ON.

4-24 Reserved

Meaning

0x22 Set the maximum voltage allowed

Byte

offset

3 Lower low byte of maximum voltage. 1 represents 1 mV.

4 Lower high byte of maximum voltage.

5 Upper low byte of maximum voltage.

6 Upper high byte of maximum voltage.

7-24 Reserved

Example: Suppose you want to set the maximum voltage to 16.23V. Since 1 represents 1mV,
therefore 16.23V translates to 16,230 in decimal. With 4 bytes in Hex, that would be 0x0003F66.
Since the bytes are ordered in little-endian format, 0x66 would be the 3rd byte, 0x3F the 4th byte,
0x00 as 5th byte, and 0x00 as the 6th byte.

Meaning

0x23 Read the maximum voltage allowed

Byte

offset

3 Lower low byte of maximum voltage. 1 represents 1 mV.

Meaning

4 Lower high byte of maximum voltage.

5 Upper low byte of maximum voltage.

6 Upper high byte of maximum voltage.

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Byte

offset

7-24 Reserved

Meaning

0x24 Set the maximum current allowed

Byte

offset

3 Lower low byte of maximum current. 1 represents 0.1 mA.

4 Lower high byte of maximum current.

5 Upper low byte of maximum current.

6 Upper high byte of maximum current.

7-24 Reserved

Example: Suppose you want to set the maximum current to 3.12A. Since 1 represents 0.1mA,

3.12A translates to 31,200 in decimal. With 4 bytes in Hex, that would be 0x000079E0. Since the
bytes are ordered in little-endian format, 0xE0 would be the 3rd byte, 0x79 the 4th byte, 0x00 as 5th
byte, and 0x00 as the 6th byte.

Meaning

0x25 Read the maximum current allowed

Byte

offset

3 Lower low byte of maximum current. 1 represents 0.1 mA.

4 Lower high byte of maximum current.

5 Upper low byte of maximum current.

6 Upper high byte of maximum current.

7-24 Reserved

Meaning

0x26 Set the maximum power allowed

Byte

offset

3 Lower low byte of maximum power. 1 represents 1 mW.

4 Lower high byte of maximum power.

5 Upper low byte of maximum power.

6 Upper high byte of maximum power.

7-24 Reserved

Meaning

Example: Suppose you want to set the maximum power to 213.45W. Since 1 represents 1mW,

213.45W translates to 213,450 in decimal. With 4 bytes in Hex, that would be 0x000341CA. Since
the bytes are ordered in little-endian format, 0xCA would be the 3rd byte, 0x41 the4th byte, 0x03 as 5

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th

byte, and 0x00 as the 6th byte.

0x27 Read the maximum power allowed

Byte

offset

3 Lower low byte of maximum power. 1 represents 1 mW.

4 Lower high byte of maximum power.

5 Upper low byte of maximum power.

6 Upper high byte of maximum power.

7-24 Reserved

0x28 Set CC, CV, CW, or CR mode

Byte

offset

3 Mode:

0 is CC
1 is CV
2 is CW
3 is CR

Meaning

Meaning

4-24 Reserved

0x29 Read the mode being used (CC, CV, CW, or CR)

Byte

offset

3 Mode:

0 is CC
1 is CV
2 is CW
3 is CR

4-24 Reserved

Meaning

0x2A Set CC mode current

Byte

offset

3 Lower low byte of current. 1 represents 0.1 mA.

4 Lower high byte of current.

5 Upper low byte of current.

6 Upper high byte of current.

Meaning

7-24 Reserved

0x2B Read CC mode current

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Byte

offset

3 Lower low byte of current. 1 represents 0.1 mA.

4 Lower high byte of current.

5 Upper low byte of current.

6 Upper high byte of current.

7-24 Reserved

0x2C Set CV mode voltage

Byte

offset

3 Lower low byte of voltage. 1 represents 1 mV.

4 Lower high byte of voltage.

5 Upper low byte of voltage.

6 Upper high byte of voltage.

7-24 Reserved

0x2D Read CV mode voltage

Meaning

Meaning

Byte

offset

3 Lower low byte of voltage. 1 represents 1 mV.

4 Lower high byte of voltage.

5 Upper low byte of voltage.

6 Upper high byte of voltage.

7-24 Reserved

0x2E Set CW mode power

Byte

offset

3 Lower low byte of power. 1 represents 1 mW.

4 Lower high byte of power.

5 Upper low byte of power.

6 Upper high byte of power.

7-24 Reserved

0x2F Read CW mode power

Meaning

Meaning

Byte

offset

3 Lower low byte of power. 1 represents 1 mW.

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Meaning

Byte

offset

4 Lower high byte of power.

5 Upper low byte of power.

6 Upper high byte of power.

7-24 Reserved

0x30 Set CR mode resistance

Byte

offset

Meaning

Meaning

3

4 Lower high byte of resistance.

5 Upper low byte of resistance.

6 Upper high byte of resistance.

7-24 Reserved

Lower low byte of resistance. 1 represents 1 m.

0x31 Read CR mode resistance

Byte

offset

3

4 Lower high byte of resistance.

5 Upper low byte of resistance.

6 Upper high byte of resistance.

7-24 Reserved

Lower low byte of resistance. 1 represents 1 m.

Meaning

0x32 Set CC mode transient current and timing

Byte

offset

Meaning

3 to 6 Value A of current in units of 0.1 mA. Little-endian 4 byte number.

7 to 8 Time for A current in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of current in units of 0.1 mA. Little-endian 4 byte number.

13 to 14 Time for B current in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

0x33 Read CC mode transient parameters

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Byte

offset

3 to 6 Value A of current in units of 0.1 mA. Little-endian 4 byte number.

7 to 8 Time for A current in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of current in units of 0.1 mA. Little-endian 4 byte number.

13 to 14 Time for B current in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

Meaning

0x34 Set CV mode transient voltage and timing

Byte

offset

3 to 6 Value A of voltage in units of 1 mV. Little-endian 4 byte number.

7 to 8 Time for A voltage in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of voltage in units of 1 mV. Little-endian 4 byte number.

Meaning

13 to 14 Time for B voltage in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

0x35 Read CV mode transient parameters

Byte

offset

3 to 6 Value A of voltage in units of 1 mV. Little-endian 4 byte number.

7 to 8 Time for A voltage in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of voltage in units of 1 mV. Little-endian 4 byte number.

13 to 14 Time for B voltage in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

Meaning

0x36 Set CW mode transient power and timing

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Byte

offset

3 to 6 Value A of power in units of 1 mW. Little-endian 4 byte number.

7 to 8 Time for A power in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of power in units of 1 mW. Little-endian 4 byte number.

13 to 14 Time for B power in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

Meaning

0x37 Read CW mode transient parameters

Byte

offset

3 to 6 Value A of power in units of 1 mW. Little-endian 4 byte number.

7 to 8 Time for A power in units of 0.1 ms. Little-endian 2 byte number.

9 to 12 Value B of power in units of 1 mW. Little-endian 4 byte number.

Meaning

13 to 14 Time for B power in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

16-24 Reserved

0x38 Set CR mode transient resistance and timing

Byte

offset

3 to 6

7 to 8 Time for A resistance in units of 0.1 ms. Little-endian 2 byte number.

9 to 12

13 to 14 Time for B resistance in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

Value A of resistance in units of 1 m. Little-endian 4 byte number.

Value B of resistance in units of 1 m. Little-endian 4 byte number.

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

Meaning

16-24 Reserved

0x39 Read CR mode transient parameters

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Byte

offset

Meaning

3 to 6

7 to 8 Time for A resistance in units of 0.1 ms. Little-endian 2 byte number.

9 to 12

13 to 14 Time for B resistance in units of 0.1 ms. Little-endian 2 byte number.

15 Transient operation:

16-24 Reserved

Value A of resistance in units of 1 m. Little-endian 4 byte number.

Value B of resistance in units of 1 m. Little-endian 4 byte number.

0 is CONTINUOUS
1 is PULSE
2 is TOGGLED

0x3A Select the list operation (CC/CV/CW/CR)

Byte

offset

3 List operation mode:

0 is constant current (CC)
1 is constant voltage (CV)
2 is constant power (CW)
3 is constant resistance (CR)

4-24 Reserved

Meaning

0x3B Read the list operation (CC/CV/CW/CR)

Byte

offset

3 List operation mode:

0 is constant current (CC)
1 is constant voltage (CV)
2 is constant power (CW)
3 is constant resistance (CR)

4-24 Reserved

Meaning

0x3C Set how lists repeat (ONCE or REPEAT)

Byte

offset

3 How lists repeat:

0 is ONCE
1 is REPEAT

4-24 Reserved

Meaning

0x3D Read how lists repeat (ONCE or REPEAT)

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Byte

offset

3 How lists repeat:

0 is ONCE
1 is REPEAT

4-24 Reserved

0x3E Set the number of list steps

Byte

offset

3 to 4 2 byte little-endian integer for number of steps

5-24 Reserved

0x3F Read the number of list steps

Byte

offset

3 to 4 2 byte little-endian integer for number of steps

5-24 Reserved

Meaning

Meaning

Meaning

0x40 Set one of the step's current and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the current in units of 0.1 mA

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

Meaning

0x41 Read one of the step's current and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the current in units of 0.1 mA

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

Meaning

0x42 Set one of the step's voltage and time values

Byte

offset

Meaning

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the voltage in units of 1 mV

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Byte

offset

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

Meaning

0x43 Read one of the step's voltage and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the voltage in units of 1 mV

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

Meaning

0x44 Set one of the step's power and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the power in units of 1 mW

Meaning

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

0x45 Read one of the step's power and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8 4 byte little-endian integer specifying the power in units of 1 mW

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

Meaning

0x46 Set one of the step's resistance and time values

Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

5 to 8

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

4 byte little-endian integer specifying the resistance in units of 1 m

Meaning

0x47 Read one of the step's resistance and time values

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Byte

offset

3 to 4 2 byte little-endian integer specifying which step number in the list

Meaning

5 to 8

9 to 10 2 byte little-endian integer specifying the step timing in units of 0.1 ms

11-24 Reserved

4 byte little-endian integer specifying the resistance in units of 1 m

0x48 Set the list file name

Byte

offset

3 to 12 List file name (ASCII characters)

13-24 Reserved

Meaning

0x49 Read the list file name

Byte

offset

3 to 12 List file name (ASCII characters)

13-24 Reserved

Meaning

0x4A Set the memory partitioning for storing lists

Byte

offset

Meaning

3 Partition scheme:

1 means 1 file of 1000 list steps
2 means 2 files of 500 list steps
4 means 4 files of 250 list steps
8 means 8 files of 120 list steps

4-24 Reserved

0x4B Read the memory partitioning for storing list steps

Byte

offset

3 Partition scheme:

1 means 1 file of 1000 list steps
2 means 2 files of 500 list steps
4 means 4 files of 250 list steps
8 means 8 files of 120 list steps

4-24 Reserved

Meaning

0x4C Save the list file

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Byte

offset

3 Storage location, a one byte integer from 1 to 8. This number must be

consistent with the number of list files allowed as set by the 0x4A command.

4-24 Reserved

Meaning

0x4D Recall the list file

Byte

offset

3 Storage location, a one byte integer from 1 to 8.

4-24 Reserved

Meaning

0x4E Set minimum voltage in battery testing

Byte

offset

3 to 6 4 byte little-endian integer specifying the minimum voltage in units of 1 mV

7-24 Reserved

Meaning

0x4F Read minimum voltage in battery testing

Byte

offset

3 to 6 4 byte little-endian integer specifying the minimum voltage in units of 1 mV

7-24 Reserved

0x50 Set timer value of for LOAD ON

Byte

offset

3 to 4 2 byte little-endian integer specifying the time in units of 1 second

5-24 Reserved

0x51 Read timer value for LOAD ON

Byte

offset

3 to 4 2 byte little-endian integer specifying the time in units of 1 second

5-24 Reserved

0x52 Disable/enable timer for LOAD ON

Byte

offset

Meaning

Meaning

Meaning

Meaning

3 0 is disable timer

1 is enable timer

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Byte

offset

4-24 Reserved

0x53 Read timer state for LOAD ON

Byte

offset

3 0 is disable timer

1 is enable timer

4-24 Reserved

0x54 Set communication address

Byte

offset

3 2 byte little-endian integer specifying the address. Must be between 0 and

0xFE, inclusive.

4-24 Reserved

0x55 Enable/disable LOCAL control

Meaning

Meaning

Meaning

Byte

offset

3 0 means to disable the Local key on the front panel

1 means to enable the Local key on the front panel

4-24 Reserved

0x56 Enable/disable remote sensing

Byte

offset

3 0 means to disable remote sensing

1 means to enable remote sensing

4-24 Reserved

0x57 Read the state of remote sensing

Byte

offset

3 0 means remote sensing is disabled

1 means remote sensing is enabled

4-24 Reserved

Meaning

Meaning

Meaning

0x58 Select trigger source

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Byte

offset

3 Trigger:

0 means immediate trigger (i.e., triggered from the front panel)
1 means external trigger from the rear panel connector
2 means a bus (software) trigger (the 0x5A command)

4-24 Reserved

0x59 Read trigger source

Byte

offset

3 Trigger:

0 means immediate trigger (i.e., triggered from the front panel)
1 means external trigger from the rear panel connector
2 means a bus (software) trigger (the 0x5A command)

4-24 Reserved

0x5A Trigger the electronic load

Byte

offset

Meaning

Meaning

Meaning

3-24 Reserved

0x5B Save DC Load's settings

Byte

offset

3 Storage register, a number between 1 and 25 inclusive

4-24 Reserved

Meaning

0x5C Recall DC Load's settings

Byte

offset

3 Storage register, a number between 1 and 25 inclusive

4-24 Reserved

Meaning

0x5D Select FIXED/SHORT/TRAN/LIST/BATTERY function

Byte

offset

3 Function:

0 means FIXED
1 means SHORT
2 means TRANSIENT
3 means LIST
4 means BATTERY

Meaning

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Byte

offset

4-24 Reserved

Meaning

0x5E Get function type (FIXED/SHORT/TRAN/LIST/BATTERY)

Byte

offset

3 Function:

0 means FIXED
1 means SHORT
2 means TRANSIENT
3 means LIST
4 means BATTERY

4-24 Reserved

Meaning

0x5F Read input voltage, current, power and relative state

Byte

offset

3 to 6 4 byte little-endian integer for terminal voltage in units of 1 mV

Meaning

7 to 10 4 byte little-endian integer for terminal current in units of 0.1 mA

11 to 14 4 byte little-endian integer for terminal power in units of 1 mW

15 Operation state register (see bit list below)

16 to 17 2 byte little-endian integer for demand state register (see bit list below)

18-24 Reserved

The operation state register's bit meanings are:

Bit Meaning

0 Calculate the new demarcation coefficient

1 Waiting for a trigger signal

2 Remote control state (1 means enabled)

3 Output state (1 means ON)

4 Local key state (0 means not enabled, 1 means enabled)

5 Remote sensing mode (1 means enabled)

6 LOAD ON timer is enabled

7 Reserved

The demand state register's bit meanings are:

Bit Meaning

0 Reversed voltage is at instrument's terminals (1 means yes)

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Bit Meaning

1 Over voltage (1 means yes)

2 Over current (1 means yes)

3 Over power (1 means yes)

4 Over temperature (1 means yes)

5 Not connect remote terminal

6 Constant current

7 Constant voltage

8 Constant power

9 Constant resistance

0x6A Get product's model, serial number, and firmware version

Byte

offset

3 to 7 ASCII model information

8 Low byte of firmware version number

9 High byte of firmware version number

Meaning

10 to 19 Instrument's serial number in ASCII

20-24 Reserved

0x6B Read the bar code information

Note: the bar code information is to be interpreted as ASCII data.

Byte

offset

3 to 5 Identity

6 to 7 Sub

7 to 9 Version

10 to 11 Year

12-24 Reserved

Meaning

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Serial number and firmware version

To find out the serial number and firmware version of the DC load, turn the instrument on. While the

SYSTEM SELFTEST message is displayed, quickly press and hold down the Shift key. By

pressing the △ and ▽ keys, you will see the following information:

120V 30A 320W Instrument's capabilities
SN: XXX-XXX-XXX Serial number
VER: X.XX Firmware version

Press the Esc key to return to normal operation of the instrument.

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In case of trouble

WARNING

Instrument won't turn on

If the instrument won't turn on when the POWER switch is pressed in, please ensure the power cord
is plugged into the back of the instrument and the other end of the cord is plugged into a live AC
power outlet.

If the instrument still won't turn on, remove the power cord from the instrument. Open the fuse
container on the rear panel and check the fuse for continuity.

If the fuse is an open circuit, replace it with the proper fuse indicated in the following table:

Model Fuse specification for 110 VAC

operation

8500 T0.5A, 250 VAC T0.3A, 250 VAC

8502 T0.5A, 250 VAC T0.3A, 250 VAC

8510 T1.25A, 250 VAC T650 mA, 250 VAC

8512 T2.5A, 250 VAC T1.25A, 250 VAC

8514 T2.5A, 250 VAC T1.25A, 250 VAC

8518 T2.5A, 250 VAC T1.25A, 250 VAC

8520 T2.5A, 250 VAC T1.25A, 250 VAC

8522 T2.5A, 250 VAC T1.25A, 250 VAC

8524 T5A, 250 VAC T2.5A, 250VAC (For 8524-220V)

8526 T5A, 250 VAC T2.5A, 250VAC (For 8526-220V)

Ensure that the fuse is rated for 250 VAC operation. Lower voltage
rated fuses are not suitable for this instrument.

Error messages during power-up

Fuse specification for 220 VAC

operation

EEPROM ERROR means the calibration data have been lost or the EEPROM is not functional.

ERROR CAL.DATA means that the calibration data have been lost.

If you experience these error messages, the instrument should be returned to B&K Precision for
service.

Keypad unlock procedure (Keypad was accidentally locked)

If you accidentally locked the keyboard, follow this procedure to unlock: The procedure below shows
how to unlock a model 8500 using “8512” as the unlock key.

1) Press Shift + Menu. You will see PASSWORD: displayed on the screen. Enter 8512, then
press the Enter key. Now you will see Connect on the display

2) Press Enter, locate menu Key Lock set, press Enter. Enter 8512, confirm with Enter, press

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Enter again. Now the password is cleared. Press Esc to exit the menu

To unlock the other DC load models, use the following unlock keys:

Model number Unlock key code

8500 8512

8502 8512

8510 8513

8512 8513

8514 8514

8518 8518

8520 8516

8522 8516

8524 8518

8526 8518

Frequency Asked Questions

Q: I cannot communicate with the instrument with my PC.

A: Check that the baudrate, address, and parity settings are configured correctly. The baudrate
and address settings inside the instrument menu (Accessible under Config menu; see Menus
section for details) must match the configurations of your computer's software interface, such
as the PV8500 software. If you are using the IT-E132 TTL to USB adapter cable, be sure to
check from “Device Manager” in Windows to verify the COM port to which the adapter is
assigned to.

Q: My load is rated for 30 A, but I cannot seem to adjust the current beyond 15 A.

A: The 8500 series has a user configurable input limit protection that can be set from the front
panel. To verify and edit these settings, press Shift + 0 to access the menu, then use the arrow
keys or rotary knob to select SYSTEM SET menu. Press Enter, and there will be menu options
for MAX CURRENT SET, MAX VOLTAGE SET, and MAX POWER SET. Respectively, these
parameters set the maximum input current, voltage, and power limit to the load. They must be
set higher than the value that you want to set in your application. Verify and change MAX
CURRENT SET, and you should be able to set to a higher current value. Be sure to press Enter
after you change the values so that the changes get saved. Also, note that MAX POWER SET
takes priority in limiting the input. For example, suppose you are using 8500, rated for 120V,
30A, 300W, and your MAX POWER SET = 100 W. You want to run CC mode and sink 5 A from a
source that has 50 V. Even if your MAX CURRENT SET = 30 A and MAX VOLTAGE SET = 120 V,
the load will limit your maximum settable current to 2 A. This is because the configuration for
maximum power limit is set to 100 W. For a 50 V source, 2 A of current will have reached the
100 W limit.

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Q: I have configured my load and turned on the input, but nothing seems to be sinking. The current
shows 0.00 A as if nothing is happening.

A: There are 2 conditional parameters in the SYSTEM SET menu that is used for specific test
applications. These parameters can affect the control of the input depending on the applicable
conditions. To disable or operate the load under normal conditions, press Shift + 0 to access
the menu system. Go to SYSTEM SET, and press Enter. Scroll until you see VOLTAGE ON SET
and VOLTAGE OFF SET. Press Enter into each of them and set both parameters to 0.00 V. Be
sure to press Enter again after changing the value so that the changes get saved.

Q: I changed some parameter settings, but my changes don't seem to apply.

A: Every time a menu option or parameter is changed, you must press Enter to save those
changes before exiting the menu. Exiting the menu without doing this will void any changes
made.

Q: How do I get the load to display more resolution from the PV8500 software?

A: When the PV8500 is starting communication, it sets all parameters to some default values.
This includes setting the range to default (10 mV, 1 mA resolution). To operate the PV8500
software in low range where an extra digit of resolution can be used, first initialize and run the
PV8500. Once the load is connected to the software and communicating, use the software
switch at the bottom to change from PC Control to Panel Control. While the load is remained
connected, front panel operation is enabled at this point. Press Shift + 0 to go into the Menu
system, and go into Config menu. Select RANGE SELECT and set it to ON. Press Enter to save.
Now, exit the menu system by pressing Esc a few times. Press Shift + Up arrow to enable 1 mV
resolution, and Shift + Down arrow to enable 0.1 mA resolution. Once set, go back to the
PV8500 GUI soft panel and change the switch from Panel Control to PC control.

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Index

Alphabetical Index

Battery...............................................................21

Battery test...............................................7, 21, 32

CC.....................................................................21

Condition............................................................21

Constant current.................................9, 11, 21, 29

Constant power..................................9, 11, 21, 30

Constant resistance........................9, 11, 21p., 31

Constant voltage.............................9, 11, 21p., 30

CR.....................................................................21

CV......................................................................21

CW.....................................................................21

Draw a constant current.......................................6

Draw a constant power........................................6

Draw a constant voltage......................................6

Dynamic condition..............................................21

Enter............................................................10, 13

Esc...............................................................10, 12

I-set....................................................................21

List................................................11, 13p., 21, 36

Local............................................................11, 21

Menu........................................................8, 12, 21

Menu system.....................................................10

Mode..................................................................21

Mode settings....................................................29

P-set..................................................................21

Present a constant resistance..............................6

R-set..................................................................22

Recall...............................................10, 12, 22, 43

Remote sensing..................................11p., 22, 42

Resistance.........................................................31

Resistance ........................................................31

S-Tran................................................................22

Shift..............................................................11, 22

Shift + △..............................................................32

Shift + ▽..............................................................32

Short................................................10, 12, 22, 32

Standard display...........................................34pp.

Store............................................................10, 22

Tran...................................................................22

Transient condition.............................................22

Transient mode..................................................21

Trigger...............................................11pp., 22, 39

V-set..................................................................22

△.........................................................................32

▽.........................................................................21

8500 DC Load Series Version: 032218 Page 75 of 76

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