BEICH CH9720 Series User manual

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OPERATION
MANUAL
CH9720 Series
Programmable DC Electronic Load
CHANGZHOU BEICH Electronic Technology Co., Ltd

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Company
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Precautions:
This manual is copyrighted by Changzhou BEICH Electronic Technology Co.,
Ltd and BEICH Electronics reserves all rights.No part of this manual may be
photocopied,reproduced,or translated without the prior written consent of
BEICH Electronics.
The manual is available for CH9720 Series Programmable DC Electronic Load
The information contained in this manual is subject to change without notice.
The latest manual electronic documents can be downloaded from the official
website of BEICH Electronics:
http://www.BEICH.com.cn
August 2017...................................... First edition
November 2017..................................Second edition
October 2018......................................Third edition
May 2019............................................Fourth Edition
The descriptions in this manual may not be all the contents of the instrument.BEICH
Electronics has the right to improve and improve the performance,function,internal structure,
appearance, accessories, packaging, etc. of this product without further explanation!The
resulting specification is inconsistent with the instrument.Confused,can contact my company.

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Safety warning:
 Electric shock
hazard
Be careful not to get an electric shock during operation,
testing and maintenance of the instrument.
Non-professionals should not open the case without
authorization. If the professional needs to replace the fuse
or perform other maintenance, be sure to unplug the power
plug and carry it with someone.
Even if the power plug has been removed, there may be
dangerous voltage on the capacitor. It should be discharged
after a few minutes.
Do not replace or adjust the internal circuits and
components of the instrument without authorization!
Input power
Please use the power supply according to the power supply
parameters specified in this instrument. Power input that
does not meet the specifications may damage the
instrument.
Please use the same specifications when replacing the fuse
 Keep away
from explosive
gas environment
Electronic instruments should not be used in flammable or
explosive atmospheres or in corrosive gases or soot
environments to avoid danger.
Other safety
matters
Do not apply an external voltage source or current source to
the test terminals of this instrument and other input and
output terminals.
Do not input AC voltage at the input.
Always observe all safety precautions in any process that uses the
equipment for operation and maintenance.Neglecting and not complying with
these safety measures and the warnings in this manual will not only affect the
performance of the instrument,but may also cause direct damage to the
instrument and may endanger personal safety.BEICH Electronic Technology Co.,
Ltd. does not bear any consequences for the consequences of not complying
with these safety precautions.

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Table of Contents
USER'S MANUAL .............................................................................................. 1
Table of Contents ..................................................................................................................... 1
CHAPTER I READY TO USE ............................................................................ 4
1.1 Check shipment .................................................................................................................. 4
1.2 Check the power supply .................................................................................................... 4
1.3 Installation fuse .................................................................................................................. 5
1.4 Connecting the power cord ............................................................................................... 5
1.5 Environmental requirements............................................................................................. 5
1.6 Start the instrument ........................................................................................................... 6
CHAPTER II OVERVIEW ................................................................................... 6
2.1 Product Introduction .......................................................................................................... 6
2.2 Technical parameters ......................................................................................................... 7
2.3 Front panel introduction .................................................................................................... 9
2.4 Rear Panel Introduction ................................................................................................... 10
2.5 Display area introduction ................................................................................................ 11
CHAPTER III MENU OPERATION................................................................... 12
3.1 Load page.......................................................................................................................... 12
3.1.1 Normal page test operation ............................................................................................ 12
Constant current mode of operation (CC) ............................................................................... 12
Constant voltage mode of operation (CV) ............................................................................... 13
Constant power mode of operation (CP) ................................................................................. 13
Constant resistance mode of operation (CR) .......................................................................... 14
CC+CV mode .......................................................................................................................... 14
CR+CV mode .......................................................................................................................... 14
3.2 Setting page................................................................................................................15
3.2.1 Load Settings Page ........................................................................................................ 15
Remote measurement ............................................................................................................. 15

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Delayed shutdown ................................................................................................................... 15
Electric flow range ................................................................................................................... 16
Maximum current ..................................................................................................................... 16
Voltage range........................................................................................................................... 17
Maximum voltage .................................................................................................................... 17
Maximum power ...................................................................................................................... 18
Starting voltage ........................................................................................................................ 18
Shutdown voltage .................................................................................................................... 19
Rising rate ................................................................................................................................ 19
Rate of decline ......................................................................................................................... 20
3.2.2 Limit Settings Page ......................................................................................................... 20
3.2.3 System Settings Page .................................................................................................... 21
3.2.4 File List Page .................................................................................................................. 22
Storage and call ....................................................................................................................... 23
Save the file to the U disk ........................................................................................................ 23
File List .................................................................................................................................... 24
3.2.5 Battery Test Page ........................................................................................................... 25
3.2.6 Dynamic Test Page ......................................................................................................... 25
3.2.7 List Test Page ................................................................................................................. 26
3.2.8 LED Test Page ................................................................................................................ 27
3.2.9 System Information Page ............................................................................................... 27
3.2.10 Data Correction Page ................................................................................................... 28
3.2.11 Firmware Upgrade Page ............................................................................................... 28
APPENDIX A REMOTE MEASUREMENT AND EXTERNAL TRIGGER ...... 29
A1 Remote measurement ...................................................................................................... 29
A2 External trigger ................................................................................................................. 29
A3 Pin configuration .............................................................................................................. 29
APPENDIX B REMOTE CONTROL .............................................................. 30
B1 RS232C Remote control system ..................................................................................... 30
B2 USB remote control system............................................................................................. 32
B3 Data format ........................................................................................................................ 33

CH9720 Programmable DC Electronic Load Instructions Chapter I Ready to use
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Chapter I Ready to use
Thank you for purchasing and using our products. Please check and check according to
the random packing list before using this instrument. If there is any discrepancy, please
contact our company as soon as possible to protect your rights.
1.1 Check shipment
After receiving this product, please carefully unpack and check according to the
following procedure:
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WARNING: If the appearance of the electronic load (such as the enclosure, front/rear
panel, LCD screen, power switch, and port connector) is damaged during transport,
do not connect the power supply and turn the power switch on, as this may result in a
risk of electric shock.
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1. Inspect the package or shock absorbing material used to package the electronic load
for damage.
2. Check the packing items attached to the electronic load in the box for damage or
defects.
3. Check that all of the packing items included with the electronic load are the specified
accessories or options.
Standard configuration Quantity Remarks
CH9720B/BU;CH9720C/CU HOST 1 set Model according to the order form
Test connection board 1 set
Power cable 1 set Different from country to region
User's manual 1 serving
Inspection report / certificate 1 serving
If you have any questions about the above checks, please contact our company or the
relevant distributor.
1.2 Check the power supply
Check that the power supply to the electronic load meets the following requirements:
Claim
Voltage 220/110(1±10%)V AC
Frequency 47～ 63Hz
Max power consumption 30VA
1.3 Installation fuse
Fuse specifications: 250V / 1A slow-blow (Slow-Blow), 5×20mm small fuse
The instrument has a fuse installed at the factory.Replacement fuses are included with
the accessories, please replace them with the specified size fuses!
To check and replace the fuse, unplug the power cord and pull out the fuse holder.

CH9720 Programmable DC Electronic Load Instructions Chapter I Ready to use
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1.4 Connecting the power cord
Check the three-core power cord, one of which is the grounding wire. When connected
to a grounded power socket, the electronic load body can be grounded to protect the user
and avoid electric shock.
After confirming that the power cord is intact, connect the electronic load to a properly
grounded electrical outlet.
WARNING: Do not use a power cord with any signs of damage to avoid electric shock.
WARNING: Use the supplied three-wire power cord with a grounding wire to ensure
that the instrument is reliably grounded.
1.5 Environmental requirements
1． Please do not use it in dusty, vibrating, direct sunlight or corrosive gases.
2． When the instrument is working normally, the temperature should be 0℃～40℃,
relative humidity ≤ 75%, please use the instrument under these conditions as
much as possible to ensure the accuracy of the measurement.
3． This instrument has been carefully designed to reduce clutter on the power
supply. However, it should be used in a low noise environment. If it is
unavoidable, install a power filter.
4． If the instrument is not used for a long time, please store it in the original box or
similar box in a ventilated room with a temperature of 5℃～40℃ and a relative
humidity of not more than 85% RH. The air should not contain harmful
impurities of the corrosion measuring instrument. And avoid direct sunlight.
5． The instrument, especially the test leads connected to the device under test,
should be kept away from strong electromagnetic fields to avoid interference
with the measurement.
6． Keep the proper ventilation space of the instrument to ensure the ventilation
and cooling environment of the instrument to prevent the temperature rise
inside the machine.
Moderate minimum space requirements: back ≥180mm, sides ≥ 60mm
7． Electrostatic protection ESD: Although the instrument has been carefully
designed to enhance the antistatic impact capability, it should be equipped with
a suitable working area to avoid electrostatic discharge.
8． Provide enough space around the instrument to quickly cut off the power cord
in an emergency.
1.6 Start the instrument
Press the power switch key in the lower left corner of the instrument to make it in the
retracted position, then turn on the power, the instrument self-test, load the configuration
information, load the initialization information and initialize the test conditions. After all the
normal, complete the boot process.
If the instrument is no longer used for a longer period of time, disconnect the power
cord from the power outlet or turn off the main switch.

CH9720 Programmable DC Electronic Load Instructions Chapter II Overview
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Chapter II Overview
The main contents of this chapter: basic product parameters and function introduction,
front and rear panel introduction and LCD display summary, and basic operation methods.
2.1 Product Introduction
CH9720X series electronic load is the new generation high performance
multi-function DC electronic load based on the professional accumulation in the field of
electronic load and wide users. The high performance ARM processor with high speed
sampling AD is adopted, so it can simulate the load feature of different power supply.
4.3 inch TFT display supports Chinese&English operation, matched with guided menu,
make the operation easier. The displayed information is rich and direct. With the
resolution of 0.0001, the voltage and current details can be monitored more
accurate.USBHOST(available for 9720BU/9720CU) can be used to save data,also for
firmware update. The comparator function with HANDLER interface can ensure the
batch test and systemization test. The load function is rich: CC, CV, CP, CR,
CR-LED(Simulate the characteristic of driver),battery discharge function(Display the
real-time discharge curve), transient test(Test the dynamic output performance of power
supply) , list test(Test the performance of the power supply under different condition).
The flexible soft and hard frame can meet the demand of group test so that to improve
the test efficiency. The smart fan control and excellent dispersion performance with the
protection alarm steps like over voltage, over current, over power, over heat and reverse
voltage polarity can make the instrument more reliable and safer. It is easier to connect
with computer for real time sampling collection and control with SCPI.
The electronic load can be widely applied for the production line of power transformer,
charger, switch power and battery, and the research field like lab.
Main Feature
1. 4.3 inch TFT LCD display, Chinese and English operation interface optional
2. Dual ARM MCU control, test and operation display completely independent,
the system runs more stable
3. Maximum 360V test voltage, easy to deal with non-isolated power supply test
or other high voltage output power supply
4. High-speed sampling AD, stable and accurate testing
5. Voltage 0.1mV, Current 0.1mA High Display Resolution
6. The slope of current rise and fall can be set, up to 0.6A/uS
7. List test can flexibly combine test mode and time to judge test results
8. Battery test mode can automatically record discharge time and capacity with
curve drawing function
9. The dynamic conversion time of 0.1mS can effectively inspect the dynamic
response of power supply
10. U disk software upgrade function,keep the latest operating version at all times
11. Standardized RS232 interface, easy access to test data
12.One-button Copy Screen and U-disk Data Storage Function
(CH9720BU/CH9720CU)

CH9720 Programmable DC Electronic Load Instructions Chapter II Overview
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2.2 Technical parameters
Model CH9720B CH9720C CH9720BU CH9720CU
Rated value
Input voltage 0~360V
Input current 0.1mA~30A
Input power 150W 300W 150W 300W
Range Accuracy Resolution
Load
accuracy
0-36V ±(0.05%+0.03%FS) 1mV
0-360V ±(0.05%+0.03%FS) 10mV
0-3A ±(0.05%+0.05%FS) 0.1mA
0-30A ±(0.05%+0.05%FS) 1mA
Rated
voltage mode
1.5V-36V ±(0.05%+0.03%FS) 1mV
1.5V-360V ±(0.05%+0.03%FS) 10mV
Rated current
mode
0-3A ±(0.05%+0.05%FS) 0.1mA
0-30A ±(0.05%+0.05%FS) 1mA
Rated
resistance
mode
0.05Ω-5Ω ±(0.2%+0.2%FS) 0.001Ω
0.5Ω-50Ω ±(0.1%+0.1%FS) 0.01Ω
5Ω-500Ω ±(0.1%+0.1%FS) 0.1Ω
500Ω-5KΩ ±(1%+1%FS) 1Ω
Rated power
mode
0-50W ±(0.1%+0.1%FS) 1mW
0-150W ±(0.1%+0.1%FS) 10mW
0-300W ±(0.1%+0.1%FS) 0.1 W
Voltage
measurement
accuracy
0-9.9999V ±(0.05%+0.03%FS) 0.1mV
10.000-99.999V ±(0.05%+0.03%FS) 1mV
100.00-360.00V ±(0.05%+0.03%FS) 10mV
Current
measurement
accuracy
0-9.9999A ±(0.05%+0.05%FS) 0.1mA
10.000-30.000 ±(0.05%+0.05%FS) 1mA
Battery test
function
Input= 0.8-360V Max measurement capacity= 999A/H
Resolution=0.1mA Timer range=1~60000sec
Dynamic test
mode A or B test time:0.05mS-999S Error<2.5% + 0.05mS
U disk
storage ＞Rating condition 5%
Impedance in
the input
terminal
≥200KΩ
Dimensions W*H*D 215mm*88mm*350mm
Weight 5.5Kg 6.5Kg 5.5Kg 6.5Kg
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CH9720 Programmable DC Electronic Load Instructions Chapter II Overview
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2.3 Front panel introduction
Order Name Description
1 Switch Turn on and off the load.
2 USB HOST interface
Connect USB disk. Support FAT16 and FAT 32.Firmware
update, data storage and load, save screen imagine(Only
available for CH9720BU/9720CU)
3 Operating function key
ON：Start up the load test.
SAVE：Save the data to U disk, the light is blinding when data
is recording (Only available for CH9720BU/9720CU)
4 LCD Display Screen Display test result, condition and system information.
5 Input key Full-functional numerical keyboard, used to input data, or
character for file name.
6 Knob Right-left adjustment for setting data and menu operation
7
Input terminal：
Red is positive and
Black is negative
 Reversed polarity input will cause big
current, dangerous
8 Function softkey
The function of 5 keys is changed as function page, which is
not fixed. In different menu, there is different function. The
function is displayed on the top of the key .
2.4 Rear Panel Introduction
1 3
5
6
4
2
4
3
2
1
8
5
6
7

CH9720 Programmable DC Electronic Load Instructions Chapter II Overview
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Order Name Description
1,2 Cooling vent  Do not block, keep well ventilated
3 Voltage switch For 110V voltage and 220V voltage switching, please pay
attention to the correct choice
4 AC power input   includes fuse, size 1A (Customizable special voltage)
5 Remote test and
trigger input interface See Appendix A for terminal pin configuration
6 RS232C serial
interface
The serial communication interface, parameter settings,
commands, etc. of the instrument and the external device
can be set and obtained by the computer to realize remote
control of the instrumentless panel.
2.5 Display area introduction
The LCD display is divided into relatively fixed areas to display specific
information for each page.
Order Name Description
1 Setting parameters
and status bar
Parameter setting with load and help hints in menu
setting
2 Main parameter display
Display real-time voltage, current and power
3 Machine internal
temperature Display the monitored internal temperature
4 Limit alarm
setting value
Set the high and low limit in normal test model, alarm
when over the limit, more details in 3.2.2
5 System icon display Display system information by means of icon
U disk is available;  remote control；
6 Clock display area Display real-time clock, change the date and time in
system interface or turn off the display.
7 Load mode Select load mode
2
1
3
4
5
6
7

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Chapter III Menu Operation
The main content of this chapter: Describes the display information and
operation of all menu display pages of electronic load.
3.1 Load Page
Field Name Brief
Constant current CC (fixed)
The electronic load consumes a constant current regardless
of whether the input voltage changes
Constant voltage CV (fixed)
The electronic load consumes enough current to keep the
input voltage constant at the set value
Flexible definition key This field is a flexible definition menu, determined by the
options of more menus.
More
Press this button will pop up the optional function page, the
menu content has fixed resistance fixed CR, power CP,
CC+CV, CR+CV, short circuit, battery test, dynamic test, list
test, led mode, can pass cursor selection or directly type the
corresponding number selection. After selection, this option
will appear in the flexible definition key position.
Start up Used to turn load input on and off
3.1.1 Normal page test operation
Constant current mode of operation (CC)
In constant current mode, the electronic load consumes a constant current regardless of
whether the input voltage changes.
I
(set current)
Load current
V
Input voltage

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Press the【Constant Current】key to enter the constant current mode. The button light will be
on. Enter the current value to be set by the numeric keypad. The entered number will be
displayed in the status bar. Press【ENT】to confirm.Press the【Start】
key or the【ON】key to start the load measurement.
Example: Set the constant current to 1.2345A
In the constant current mode,input 1.2345 through the numeric keypad,
press【ENT】to confirm
In the load start state,you can use the【▲】or【▼】key to move the cursor,
rotate the knob to change the setting parameters,or reset the parameters by
the numeric keys,and the load will automatically follow the changed value.
Constant voltage mode of operation (CV)
In constant voltage mode, the electronic load will consume enough current to keep the
input voltage constant at the set point.
V
(set voltage)
Input voltage
I
Load current
Hint: Please refer to the constant current setting method for setting and changing the
voltage setting value.
Note: When the source voltage is less than the set value, the load will not work
at constant voltage.
Note: The difference between the source voltage and the set voltage will fall on
the source resistance and lead resistance. If the difference is large and
the internal resistance is small, the load may consume a large current!
Constant power mode of operation (CP)
In constant power mode, the load consumes a constant amount of power.When the
input voltage changes, the load will regulate the current to maintain the power consumed.
V
V1
Input voltage
V2 (set power P)
V3

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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I1 I2 I3 I
Load current
In other load modes, press the【More】key to enter the menu to select the constant
power mode, and use the【Start】key to start or stop the work.
When the load is not activated, you can change the set value with the cursor and knob,
or press the【Fix Power】key to enter the new value with the numeric keys.
Hint:Please refer to the constant current method for changing the power setting value.
Constant resistance mode of operation (CR)
In constant resistance mode, the load is equivalent to a constant resistance, and the
load consumes current that changes as the input voltage changes.
I
Slope (resistance setting)
Load current
V
Input voltage
Hint:Please refer to the constant current method to change the resistance setting value.
CC+CV mode
The CC+CV mode is a constant current plus voltage mode. The main function is to
prevent damage caused by overcurrent discharge of the tested power supply.Setup and test
methods:
1. In the more measurement mode, the cursor is selected to CC+CV and then press【ENT】
to confirm. Press【Constant Current】to set the constant current parameter, and press
【Constant Voltage】to set the load constant voltage working parameter.
2. Press the start button to start the measurement.If the load meter determines that the
constant current can be loaded to the set value,the load works in the constant current
mode.If the load meter determines that the power supply current cannot be output to the
set value,it will switch to the constant voltage working mode.The max output current.
CR+CV mode
The CR+CV mode is consistent with the CC+CV mode function. The setting method
and test method refer to the CC+CV mode.

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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3.2 Settings Page
Press the【Set】key to enter the main menu page. Use the arrow keys to turn the knob to
move the cursor or directly enter the first two digits of the menu to select the menu you want
to enter.
3.2.1 Load Settings Page
Select the cursor to load setting option under the main menu, press【ENT】to enter or
directly press the number 01 to enter
Remote measurement
In CV, CR, CP mode, the voltage sampling accuracy will affect the working accuracy of
the electronic load.When the load consumes a large current, a voltage drop will be
generated on the connection line of the tested power supply to the load. To ensure
measurement accuracy, the load provides a remote measurement end on the rear panel,
and the user can use the terminal to measure the output of the instrument under test
terminal voltage.
Use the【ENT】key to change the menu settings.Each press of the【ENT】key will switch
between on and off.
Voltage remote measurement = On:Turn on the remote test, the instrument samples
the voltage from the remote measurement terminal on the rear panel
Voltage remote measurement = Off: Turn off the remote test and the instrument
samples the voltage from the front panel load input.

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Hint: Please refer to Appendix A for the rear panel Sense interface pin configuration.
Delayed shutdown
Automatic delay shutdown can be applied to four basic load modes: constant voltage,
constant current, constant power, and fixed resistance. If automatic delay shutdown is
turned on, the load will be timed in seconds after the load is started. After the break, the load
will automatically turn off.
Type the number key directly, press the 【ENT】 key to confirm, and enter 0 to turn it off.
Hint: the unit is seconds (s), the setting range is 1 ~ 99999s.
Hint: If the setting value is 0 or close to 0, the automatic shutdown display is “Off”,
which means the function is turned off.
Electric flow range
This model is fixed to a low current range and cannot be switched.
Maximum current
The maximum load current has two main functions:
1. The settable constant current value (Is=) will be limited to below this maximum
current;
2. In the case of CV,CP, CR and short-circuit test, when the load current exceeds the
maximum current, the instrument will alarm and display over-current protection (OC). If it
exceeds a large value, the load will automatically shut down.
Hint: Enter the number directly when setting the maximum current, press【ENT】to
confirm.
Voltage range
This model is fixed to a low voltage range and cannot be switched.
Maximum voltage
Setting the maximum input voltage has two main functions:
1. The settable constant voltage value (Vs=) will be limited to below this maximum
voltage;
2. When the input voltage exceeds the maximum voltage, the electronic load will alarm
and display “Exceed Voltage!!!” and the load will be turned off;
Hint:Enter the number directly when setting the maximum voltage,press【ENT】to
confirm.
Maximum power
Used to declare the maximum power that the load is allowed to consume. Once the actual
power consumption exceeds this value, the instrument will alarm and display power
protection (OP), which may cause the load to automatically shut down.
Hint: Enter the number directly when setting the maximum power, press【ENT】to
confirm.

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Starting voltage
The minimum starting voltage can be applied to four basic load modes: constant voltage,
constant current, constant power, and fixed resistance. If the minimum starting voltage is
turned on, after the load is started, when the input voltage is less than the minimum starting
voltage, the load will be in the waiting process. The status information area is displayed as
“。。。。” and the load is automatically started once the input voltage exceeds the minimum
start up voltage.
Example: If the minimum starting voltage is set to 1.25V, select menu to minimum
starting voltage, type【1】【.】【2】【5】, press【ENT】to confirm, the default
unit is V.
Hint: If the set value is 0 or close to 0, the minimum start voltage is displayed as
“Off”, which means the function is turned off.
Hint: After the start up voltage is set in the list test mode, the power-on self-start
function will be turned on. When the instrument judges that the input voltage is
higher than the set voltage, the list test starts, and the test sequence is stopped
after the completion of the test.
Shutdown voltage
The minimum shutdown voltage can be applied to four basic load modes: constant voltage,
constant current, constant power, and fixed resistance. If the auto-shutdown voltage is
turned on, after the load is started, after the input voltage is less than the auto-shutdown
voltage, the load will be Automatically shut down.
Hint: The setting method is the same as the minimum starting voltage.
Hint: If the set value is 0 or close to 0, the auto-shutdown voltage is displayed as
“Off”, which turns off this function.
Rising rate
Used to set the load climb rate to reduce the overcurrent surge caused by sudden load in
some cases.After inputting the data, press【ENT】to confirm, the maximum settable current
is 0.600A/uS.
Rate of decline
Used to set the time from normal working state to no load.After inputting the data, press
【ENT】to confirm, the maximum settable current is 0.600A/uS.
Hint: After all menu settings are completed, you can press【Enter Test】to enter the
main test page directly, or press the【Back】key to return to the main menu.
3.2.2 Limit Settings Page

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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The voltage, current, and power judgment parameters can be set under this page, and the
judgment result is displayed in the display area of the main test interface. If the value
exceeds the set value, the indication will be highlighted in red.
Hint: Move the cursor to the position you want to set, press the【ENT】key to confirm
the number directly. The limit judgment can be turned on or off by pressing the
【ENT】key. After the setting is completed,press the【Enter Test】key to directly
enter the main test page, or Press the 【Back】 key to return to the main menu.
3.2.3 System Settings Page
In this interface, you can set and change the instrument system style and application. Press
【ENT】to switch the menu content at the cursor. Press the number key and press the
【ENT】key to confirm the date and time.
Menu name Secondary menu content
Display style
Simple gray
Green grass green
Cool black
Elegant blue
Trigger source
Manual:Triggered by the “TRIG” key on the instrument panel
External:External trigger,triggered by Sense on the rear panel
Bus:Triggered by programmable commands on RS232C interface
Language Chinese
English
Communication
mode
RS232C
USB-CDC
USB-TMC
Boot settings Defaults
Last value
Local address After entering the number, press【ENT】to confirm
Touch-tone Turn on
Shut down

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Baud rate 4800 9600 19200 38400 57600
Keyboard lock Lock 0-9 numeric keypad when open
Shut down
Multi-machine
mode
Stand-alone
Multi-machine
Knob lock Turn on
Shut down
Factory settings After the recovery is confirmed, all settings will be restored to the
factory values. Please operate with caution.
Acquisition
frequency Used to set the data acquisition time when u disk data is saved.
Date Press the number key directly and press the 【ENT】 key to confirm
and move the cursor to the next item.
Time Press the number key directly and press the 【ENT】 key to confirm
and move the cursor to the next item.
3.2.4 File List Page
Storage and call
Through the store and recall functions, parameters can be saved instantly, measurement
settings saved to an internal ROM or external USB memory, and save the measurement
node or screen snapshot to the external USB memory.
Storage function
The following save functions can be implemented through the instrument's storage system:
 Instantly save user correction data and settings;
 Instantly save measurement setup parameters, system configuration parameters;
Save the measurement setup parameters as a file in the internal ROM memory or
external USB memory;
 Save the screenshot file to USB memory (screen capture function);
 Save the measurement results to the USB memory (data logging function).

CH9720 Programmable DC Electronic Load Instructions Chapter III Menu Operation
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Call function
After storage, the following call functions can be implemented:
 Automatically call user correction data and settings in real time;
 Instantaneously call the measurement setup parameters automatically;
 Automatically call system configuration parameters in real time;
 Loading the measurement settings file in the internal ROM or external USB memory
through the file management function;
Storage media type
The instrument uses the following media to save information:
Media type Use
Internal RAM (battery powered) Instantly save measurement parameters and system
configuration
Internal FLASH ROM User correction data and its settings, measurement
settings file
External USB memory (U disk) Measurement setup file, screenshot file, data log file
Hint:On the file list page,type the number directly,0-100 for RAM storage,100 or more for U
disk storage,the memory type will be displayed on the right side of the operation
bar,then enter the file code and press the save button to confirm the save.
U disk file structure
After connecting the USB memory to the instrument, the instrument organizes and uses the
folders and files on the memory according to a predetermined structural scheme.
As shown in the following table:
File type Extension
name
Max number of
files*1 File path*2
Measurement setup file EST 500 \CH9720\SETUP
Data Record File CSV 200 \CH9720\DATA
Screen snapshot file GIF，BMP，PNG 200 \CH9720\IMAGE
Upgrade file 36U 10 Root directory
Note *1. Refers to the maximum number of extensions using the same extension;
Note *2. Folders differ according to different instrument models
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Note: The folder is automatically created by the instrument. In addition to the upgrade
file, the file name is also automatically generated by the instrument.
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The USB memory should conform to the FAT16 or FAT32 file system and be formatted using
FAT16 or FAT32.
If there is a U disk that the instrument can’t recognize, please use another formatted U disk.
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