B+K precision 1785B User manual

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Version: November 3, 2010
Instruction Manual
Model 1785B, 1786B, 1787B & 1788 Programmable DC Power Supplies

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Content
Content..................................................................................................................................................... 2
Quick Reference............................................................................................................................................. 3
About your safety.................................................................................................................................... 3
General information........................................................................................................................ 3
Protection from electric shock...................................................................................................... 3
Definition of users........................................................................................................................... 3
Certification and Warranty..................................................................................................................... 4
Certification...................................................................................................................................... 4
Introduction.............................................................................................................................................. 4
The Front Panel at a Glance................................................................................................................. 5
Function keys description...................................................................................................................... 5
Menu description.................................................................................................................................... 6
Display annunciators.............................................................................................................................. 6
The Rear Panel at a Glance................................................................................................................. 7
Chapter 1 Quick Start.................................................................................................................................... 7
1.1 Preliminary Checkout...................................................................................................................... 8
1.2 Output Checkout.............................................................................................................................. 8
1.2.1 Voltage Output Checkout.................................................................................................... 8
1.2.2 Current Output Checkout.................................................................................................... 9
1.3 If the Power Supply Does Not Turn On........................................................................................ 9
1.4 To Adjust the Carrying Handle..................................................................................................... 10
1.5 To Rack Mount the Instrument..................................................................................................... 10
Chapter 2 Specifications.............................................................................................................................. 13
2.1 Specifications ................................................................................................................................. 13
2.2 Supplemental Characteristics...................................................................................................... 14
Chapter 3 Front-panel Operation............................................................................................................... 16
3.1 Front-panel Operation Overview................................................................................................. 16
3.2 Constant Voltage Operation......................................................................................................... 16
3.3 Constant Current Operation......................................................................................................... 17
3.4 Saving and Recalling Operation.................................................................................................. 17
3.5 Menu Operation............................................................................................................................. 17
Chapter 4 Remote Operation Mode.......................................................................................................... 20
4.1 IT-E131 Communication cable..................................................................................................... 20
4.2 Communication setting................................................................................................................. 20
4.3 Frame format.................................................................................................................................. 21
Packet structure............................................................................................................................ 21
Status packets............................................................................................................................... 22
4.4 Communication protocol............................................................................................................... 24
Chapter 5 PV1785B-1788 Software.......................................................................................................... 30
5.1 Introduction..................................................................................................................................... 30
5.2 System Installation......................................................................................................................... 30
5.3 Functions of PV-1785B-1788....................................................................................................... 30
5.3.1Configure the system.......................................................................................................... 32
5.3.2 Status bar............................................................................................................................. 32
5.3.3 Setting Voltage and current............................................................................................... 33
5.3.4. GO/NG Test Function........................................................................................................ 35
5.3.5 Save and Open................................................................................................................... 35
5.3.6 Present Voltage/Current Chart......................................................................................... 35
5.3.7 Chart Description................................................................................................................ 36

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Quick Reference
About your safety
Pease review the following safety precautions before operating our equipment.
General information
The following safety precautions should be observed before using this product and any
associated instrumentations. Although some instruments and accessories would be
used with non-hazardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recognize shock hazards
and are familiar with the safety precautions required to avoid possible injury. Read and
follow all installation, operation, and maintenance information carefully before using the
product. Refer to this manual for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product
may be impaired.
Before performing any maintenance, disconnect the line cord and all test cables.
Protection from electric shock
Operators of this instrument must be protected from electric shock at all times. The
responsible body must ensure that operators are prevented access and/or insulated
from every connection point. In some cases, connections must be exposed to potential
human contact. Product operators in these circumstances must be trained to protect
themselves from the risk of electric shock. If the circuit is capable of operating at or
above 1000 volts, no conductive part of the circuit may be exposed.
Definition of users
Responsible body is the individual or group responsible for the use and maintenance of
equipment is operated within its specifications and operating limits, and for ensuring
that operators are adequately trained.
Operators use the product for its intended function. They must be trained in electrical
safety procedures and proper use of the instrument. They must be protected from
electric shock and contact with hazardous live circuits.
Service is only to be performed by qualified service personnel.
Safety symbols and terms
Connect it to safety earth ground using the wire recommended in the user
manual.
The symbol on an instrument indicates that the user should refer to the
operating instructions located in the manual.
High voltage danger

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Certification and Warranty
Certification
Wecertify that this product met its published specifications at time of shipment from the
factory.
Introduction
The 1785B - 1788 Series power supplies are high performance single-output
programmable DC power supplies with communication interface. The combination of
bench-top and system features in these power supplies provides versatile solutions for
your design and test requirements.
Convenient bench-top features:
• Nice appearance, small-size and light weight
• VFD display
• Soft Rubber numeric keypad
• Adjustable & constant voltage outputs
• Adjustable & constant current outputs
• Output on/off
• High accuracy and high resolution
• Excellent load and line regulation
• Low ripple and noise
• Limit voltage protection
• Over current/temperature protection
• Sixteen operating states storage
• May be used in series or parallel modes with additional power supplies

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The Front Panel at a Glance
①10 digits VFD display
②Status information for operating mode and working status
③Power switch
④Number keys
⑤Function keys
⑥UP/DOWN and ENTER key
⑦Output terminals
Function keys description
Set the output voltage value
Set the current value
Save the present settings to a specified register location(1~16)
Recall a saved settings from location ‘‘1’’through ‘‘16’
Menu function to set related parameters of the power supply
Output ON/OFF, to enable/disable the output
V-set
I-set
Save
Menu
Recall
Out on/off

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Menu description
>MAX VOLT
Set the maximum output voltage value
>INIT OUT
Initiate the output state to ON or not
>INIT VOL
Initiate the output voltage to 0 volt or not
>KEY SOUN
Switch On/Off the buzzer sound when you press
any key
>BAUD
RATE
Set the communication baud rate
>ADDR
Set the communication address
>KEY LOCK
Set the password for function keys
>EXIT
Exit
Display annunciators
OFF
The power supply’s
output is off
Timer
Not used
CV
Constant voltage
mode
Sense
Not used
CC
Constant current
mode
Ext
Not used
*
Not used
Adrs
The instrument is
communicating with an
IT-E131/IT-E132/IT-E133
Meter
Meter mode
Rmt
The instrument is in remote
state. The only active key is
the Local KEY.
Shift
Not used
Error
The instrument has error
OVP
Over voltage protect
state
Prot
Not used
OCP
Over current protect
state
Lock
The keyboard is locked by a
password
Menu

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The Rear Panel at a Glance
124
351 24 35
①Cooling window
②DB9 interface connector
③110V/220V selector
④Fuse
⑤Power socket
Chapter 1 Quick Start
One of the first things you will want to do with your power supply is to become acquainted with the front
panel. The exercises in this chapter prepare the power supply for use and help you get familiar with

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some of its front-panel operations.
This chapter is intended for both the experienced and the inexperienced user because it calls attention
to certain checks that should be made prior to operation.
1.1 Preliminary Checkout
The following steps help you verify that the power supply is ready for use.
1．Check the list of supplied items.
Verify that you have received the following items with your power supply. If anything is missing, contact
your nearest Sales Office.
□One power cord for your location
□This User’s Manual.
□Communication cable
2．Connect the power cord and turn on the power supply.
When you turn on the power supply, the front-panel display will light up briefly while the power supply
performs its power-on self-test. All the VFD annunciators will light up at once. To review the display with
all annunciators, you can check if there is any stroke loss on any annunciator. If there isn’t any response
when you power on the power supply, please see Section 1.5 on page 10 for some service information.
If the EEPROM was damaged or the latest operation data in EEPROM was lost, the VFD will display as
follows:
If the calibration data in EEPROM was lost, the VFD will display as follows:
1.2 Output Checkout
The following procedures check to ensure that the power supply develops its rated outputs and properly
responds to operation from the front panel.
1.2.1 Voltage Output Checkout
The following steps verify basic voltage functions without load.
1. Turn on the power supply.
ERR EEPROM
ERROR CAL
Warning
: Your power supply is equipped with a 3-wire grounding type power cord;
the third conductor being the ground. The power supply is grounded only when the
power-line cord is plugged into an appropriate receptacle. Do not operate your power
supply without adequate cabinet ground connection.

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2. Enable the outputs.
Press key to let the ON annunciator and the CV annunciator turn on to light.
Notice:if the voltage value flash, then the power supply is in Set mode, ‘‘Set mode’’ means that the VFD
display shows the setting output voltage and current. Or the power supply is in Meter mode, ‘Meter
mode” means that the VFD display shows the actual output voltage and current and the ”Meter”
annunciator is lit.
3. Check that the front-panel voltmeter properly responds to number keys
Set some different voltage values, then wait till the Meter mode to check if the VFD displayed voltage
value is the same as the set voltage value, and to check if the VFD displayed current value is nearly
zero.
4. Ensure that the voltage can be adjusted from zero to the full rated value.
1.2.2 Current Output Checkout
The following steps check basic current functions with a short across the power supply’s output.
1. Turn on the power supply.
2. Disable the output
Press key to ensure that the output is disabled. The OFF annunciator is turned on.
3. Connect a short across (+) and (-) output terminals with an insulated test lead.
Use a wire size sufficient to handle the maximum current.
4. Enable the output.
Press key to ensure that the output is enabled. The OFF annunciator is turned off.
5. Adjust the voltage value to 1.0 volt.
Adjust the voltage to 1.0 volt to ensure the power supply is in CC operation mode. The CC annunciator
will turn on.
6. Adjust the current value.
Set some different voltage values, then wait till the Meter mode to check if the VFD displayed current
value is the same as the set voltage value, and to check if the VFD displayed voltage value is nearly
zero.
7. Ensure that the current can be adjusted from zero to the full rated value.
8. Turn off the power supply and remove the short wire from the output terminals.
1.3 If the Power Supply Does Not Turn On
Use the following steps to help solve problems you might encounter when turning on the instrument. If
you need more help, refer to chapter 6 for instructions on returning the instrument to the supplier for
service.
Warning：
To satisfy safety requirements, load wires must be heavy enough not to
overheat when carrying the maximum short-circuit output current of the power
supply. If there is more than one load, then any pair of load wires must be capable of
safety carrying the full-rated current of the power supply.
Out on/off
Out on/off
Out on/off

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1. Verify that there is AC power to the power supply.
First, verify that the power cord is firmly plugged into the power receptacle on the rear panel of the power
supply. You should also make sure that the power source you plugged the power supply into is
energized. Then, verify that the power supply is turned on.
2. Verify the power-line voltage setting.
The line voltage is set to the proper value for your country (110VAC or 220VAC). Change the voltage
setting if it’s not correct.
3. Verify that the correct power-line fuse is installed.
If the fuse was damaged, please see the table below to replace the fuse for your power supply.
Model
Fuse Description
1785B,
1786B,
1787B
Fuse 2.5A T 250V for 220VAC
Fuse 5A T 250V for 110VAC
1788
Fuse 3.15A T 250V for 220VAC
Fuse 6.3A T 250V for 110VAC
1.4 To Adjust the Carrying Handle
To adjust the position, grasp the handle by the sides and pull outward. Then, rotate the handle to the
desired position.
Bench-top viewing positions Carrying position
1.5 To Rack Mount the Instrument
You can mount the power supply in a standard 19-inch rack cabinet using the IT-E151 rack mount kit.

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Note: Remove the carrying handle and the two plastic ears before rack-mounting the instrument.
To remove the handle, grasp the handle by sides and pull outwards and rotate it to a special position to let
the arrow on the handle and the arrow on the plastic ears be in opposite directions, then pull the handle
outward. After removing the handle, you can use a screwdriver to remove the two plastic ears.
To rack mount a single instrument, order rack mount kit IT-E151
Side view of rack mounting a single instrument
To rack mount two instruments side-by-side, order rack mount kit IT-E151, you
needn’t to use the front cover panel.

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Dimension unit (mm)

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Chapter 2 Specifications
2.1 Specifications
Parameter 1785B 1786B 1787B 1788
Output Ratings,
( 0 °C - 40 °C)
Voltage
0 ~18
V
0 ~32
V
0 ~72
V
0 ~32
V
Current 0 ~5 A 0 ~3 A
0~1.5
V
0~6 A
LVP
0 ~19
V
0 ~33
V
0 ~73
V
0 ~33
V
Load Regulation,
±(％
of output+offset)
Voltage (rated current < 3 A) <0.01％+ 3 mV
(rated current< 10 A) <0.02
％
+ 5 mV
Current <0.1％+ 3 mA
Line Regulation,
±(％
of output+offset)
Voltage <0.1％+ 3 mV
Current <0.1％+ 2 mA
Programming
Resolution
Voltage 10 mV
Current 10 mA
Readback Resolution Voltage
10 mV(<20 V)
100 mV(≥20 V)
Current 10 mA
Programming
Accuracy, 12months,
(@ 25 °C ± 5 °C)
±(％
of output+offset)
Voltage <0.05% + 10 mV
Current <0.2％+10 mA
Readback Accuracy
12months,
(25 °C ± 5 °C)
±(％
of output+offset)
Voltage <0.05%+15 mV(<20 V),<0.05%+120
mV(≥20 V)
Current <0.1％+15 mA
Ripple
(20Hz ~20MHz)
Voltage ≤0.5 mVrms/3 mVp-p
Current 5 mArms
Temperature
Coefficient,
(0 °C ~ 40 °C)
±(％
of output+offset)
Voltage <0.02%+5 mV
Current <0.1％+5 mA
Readback
Temperature,
Coefficient,
±(％
of output+offset)
Voltage <0.02%+15 mV(<20 V),<0.02%+120
mV(≥20 V)
Current <0.1％+15 mA

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2.2 Supplemental Characteristics
State Storage Memory
Sixteen (16) user-configurable stored states
Recommended Calibration Interval
1 year
AC Input Ratings (selectable via switch on the rear panel)
Option OP1: 220VAC ± 10%, 47 to 63 Hz
Option OP2: 110 VAC ± 10%, 47 to 63 Hz
Maximum input power
350VA
Cooling
Fan cooled
Operating Temperature
32 to 104 °F (0 to 40 °C) for full rated output
Storage Temperature
-68 to 158 °F (-20 to 70 °C) for storage environment.
Environmental Conditions
Designed for indoor use in an installation category II, pollution degree 2 environment. Designed to
operate at maximum relative humidity of 95% and at altitudes of up to 2000 meters.
Weight
Type
1785B
1786B
1787B
1788
N.W
12.3Lbs.
5.6Kg
14.8Lbs.
6.7Kg
14.8Lbs.
6.7Kg
14.8Lbs.
6.7Kg
G.W
14Lbs.
6.4Kg
16.5Lbs.
7.5Kg
16.5Lbs.
7.5Kg
16.5Lbs.
7.5Kg
Dimensions WxHxD*
10” x 4.16” x 15” (255.7mm x 105.7mm x 382.7mm)
Specifications are subject to change without notice.
To ensure the most current version of this manual, please download the current version
here: http://www.bkprecision.com/search/manual/1785B
For current up-to-date product information, please visit www.bkprecision.com

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(Unit: mm)

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Chapter 3 Front-panel Operation
So far you have learned how to install your power supply and do quick start. During the quick start, you
were briefly introduced to operating from the front panel as you learned how to check basic voltage and
current functions. This chapter describes in detail the use of the front-panel keys and shows how they
are used to accomplish power supply operation.
This chapter is divided into the following sections:
• Front-Panel Operation Overview‚ on page 14
• Constant Voltage Operation‚ on page 15
• Constant Current Operation‚ on page 15
• Storing and Recalling Operating States‚ on page 15
• MENU operation, starting on page 16
3.1 Front-panel Operation Overview
The following section describes an overview of the front-panel keys before operating your power supply.
1. The power supply is shipped from the factory configured in the front-panel operation mode. At
power-on, the power supply is automatically set to operate in the front-panel operation mode. When in
this mode, the front panel keys can be used.
2. When the power supply is in remote operation mode, you cannot use the front-panel. A change
between front-panel and remote operation modes will not result in any change in the output
parameters. You can change the front-panel and remote operation modes by computer.
3. The power supply is in Meter mode when it is powered on, and the VFD will display the actual voltage
and current output value. And in this mode, if any non-functional key is pressed, the power supply will
changed to Set mode, and the VFD will display the adjusted voltage and current value. In Set mode,
the set voltage value will flash, you can press ▲and ▼keys to adjust the voltage value. In Set
mode, the power supply will turn back to Meter mode if there is no any key is pressed for 3 seconds.
4. The output of the power supply can be enabled or disabled from the front panel by pressing
key. When the output is on, the ON annunciator will turn off.
5. The VFD display shows the present operating status of the power supply with annunciators. For
example, the power supply is operating in CV mode, and then the CV annunciator will turn on. If, the
power supply is remotely controlled, the Rmt annunciator will also turn on, See ‘‘Display
Annunciators’’.
3.2 Constant Voltage Operation
The constant voltage range is from 0V to the maximum voltage value of each model. It is very easy for
you to set the constant voltage output. You have 2 solutions to set the constant voltage value.
Solution 1:
Out on/off

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Step1. Power on the Power Supply
Step2. Press the ▲and ▼keys to change the value
Solution 2:
Step1. Power on the instrument
Step2. Press key.
Step3. Use the numeric keys to or ▲and ▼keys to change the voltage value.
Step4. Press to confirm the value
3.3 Constant Current Operation
The constant current output range is from 0A to the maximum current value of each type. It is very easy
for you to set the constant current output.
Step1. Power on the Power Supply
Step2. Press key
Step3. Use the numeric keys to or use ▲and ▼keys to change the current value
Step4. Press key to confirm the value
3.4 Saving and Recalling Operation
You can store up to 16 different output states in storage register locations (1 to 16). Each output state
includes Constant voltage value, Constant current value and Maximum output voltage value. When
shipped from factory, storage locations “1” through “16” are empty. You can recall the saved settings by
Recall function.
Step1. After you setting an output state (CV value, CC value and Maximum voltage), press key.
Step2.Use the numeric keys to or ▲and ▼keys to select the memory location (the range
is 1 to 16) which you want to store in.
Step3. Press to confirm the memory location.
Step4. Press key.
Step5. Use numeric keys to or ▲and ▼keys to select the states which you want to
recall.
Step6. Press key to confirm. Then the saved settings will come on.
3.5 Menu Operation
Set Maximum voltage(>MAX VOLT）
Please be well known that the Max voltage value should be in the range of each type of Power
V-Set
Enter
Enter
Save
Recall
Enter
Enter
I-Set
9
9
9
9
0
0
0
0
Note:
1. If the function keys were locked by password, you need to enter the correct
password after you press function keys (V-set, I-set, Save, Recall and Menu), then
you can do the settings.
2. If you want to cancel a function operation (V-set, I-set, Save, Recall or Menu), just
press key to exit.
Esc

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supply.
Step1. Press key.
Step2. Select >MAX VOLT by using▲and ▼key.
Step3. Press key.
Step4. Change the voltage value by using numeric keys to or ▲and ▼key.
Step5. Press key.
Initiating the Output state(>INIT OUT)
This instruction can initiate the output state when the power supply is powered on. If you select ON,
the power supply will initiate the output to OFF state when the power supply is powered on. If you
select OFF, the output will remain the same state as last time you turned off the power supply
Initiating the Output Voltage (>INIT VOLT)
This instruction can set the initial output voltage. If you select ON, the power supply will initiate the
output voltage to 0Volt when the power supply is powered on. If you select OFF, the output voltage
will remain as the same volts as the last time you turned off the power supply
Setting the Key Sound(>KEY SOUND)
This instruction can switch on/off the buzzing sound when you press any key, If you select ON, the
buzzer will sound when any key was pressed. If you select OFF, the buzzer will not sound when the
keys were pressed.
Setting the Baud Rate(>BAUDRATE)
This instruction can change the communication baud rate for the power supply, the baud rate
range is 4800，9600，19200 or 38400。Before the communication, you must make sure that there
is same baud rate between the power supply and the computer.
Enter
Menu
Note: After you setting the maximum voltage value, the output voltage setup should
be in the range from 0 volt to maximum voltage. The default maximum voltage is
the full voltage range of its model.
Note:
Default selection is ON and the output state is always OFF state.
Note:
Default setting is ON and the output voltage is 0 volt.
Note:
Default setting is ON; the buzzer will sound when you press any key.
Enter
9
0

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Setting Address (>ADDRESS)
This instruction can set the communication address for each power supply. The address range is
from 0 to 30. Before the communication, you must make sure that there is same address between
the power supply and the computer.
Setting password for function keys(>KEY LOCK)
This instruction can set a password (1 through 4 digits) to lock the function keys operation. After
setting the password, all the function keys on the front panel will be locked except the OUT on/off
key. You must enter the correct password to unlock them, then you can continue to do the function
key operation. If you don’t want to lock the function keys, please don’t press any number key when
you enter the >KEY LOCK instruction, just press ENTER key to unlock it.
Note:
Default baud rate is 4800.
Note: Default address is 0. When the power supply receives a frame instruction from
computer, the LINK indicator will light on; it means that the power supply started
to communicate with computer. If the power supply hasn’t received the signal
from computer for 3 seconds, the LINK indicator will be turned off and it means
that the power supply can not communicate with computer.
Note:
When shipped from factory, there is no password and function keys are
unlocked. The start bit of your desired password shouldn’t be 0.

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Chapter 4 Remote Operation Mode
The DB9 interface connector on the rear panel of the power supply can be transferred to RS-232
interface, the following information will tell you how to use the computer to control the output of the
power supply.
4.1 IT-E131 Communication cable
The DB9 interface connector on the rear panel of power supply is TTL voltage level; you can use
the communication cable (IT-E131) to connect the DB9 interface connector of the power supply
and the RS-232 interface connector of computer for the communication.
Computer side TTL→RS232 Cable (IT-E131) PS side
PC Load
IT-E131 communication cable
COMPUTER
INSTRUMENT
RX
TX
IT-E131 ISOLATED
COMMUNICATION CABLE
TTL(5V)RS232 ISOLATION
859666668889942311
IT
COMPUTER
INSTRUMENT
RX
TX
IT-E131 ISOLATED
COMMUNICATION CABLE
TTL(5V)RS232 ISOLATION
859666668889942311
IT
Power
supply
PC
4.2 Communication setting
Before using the remote operation mode, please make sure that the baud rate and communication
address in power supply are the same as in the computer software, otherwise, the communication will
fail, you can change the baud rate and communication address from the front panel or from computer.
1．Address: the range is from 0 to 254，default setting is 0
2．Baud rate: 4800,9600,19200 and 38400 are selectable, default setting is 4800
3．Data bit：8 bit
4．Stop bit：1
5．Parity：None
Start
Bit 8 Data Bits Stop Bit
PARITY = NONE
Note:
It will not work if you connect the DB9 interface connector of the power
supply to the RS232 interface connector of computer directly by a standard
RS232 cable. Please use IT-E131 to connect them.