Digi DS-425 Service Manual

V1.0

SERVICE MANUAL

Model: DS-425

Edition Month Year

1

st

September 1998

2nd December 1998

3rd April 2001
4

th

January 2002

Shanghai Teraoka Electronic Co., Ltd. --- Technical Service Dept.

Ting Lin Industrial Development Zone Jin Shan District, Shanghai P. R. China 201505

Tel: [phone] Fax: [phone] E- mail: [e-mail]

DS-425 Service Manual --- V1.04

Page No. 1

CONTENTS

1. General Specification

1.1. Overall Dimension ---------------------------------------------------------------------------- 1

1.2. Display Panel ------------------------------------------------------------------------------------- 1

1.3. Main Feature -------------------------------------------------------------------------------------- 2

1.4. Operation Condition ---------------------------------------------------------------------------- 2

1.5. Main Function -------------------------------------------------------------------------------------- 2

1.6. Layout And Function ---------------------------------------------------------------------------- 3

2. Initial Set-Up

2.1. Stopper Screws ---------------------------------------------------------------------------- 4

2.2. Adjustment -------------------------------------------------------------------------------------- 5

2.3. Location of the SPAN SW ------------------------------------------------------------------ 5

2.4. Span Switch Check ---------------------------------------------------------------------------- 6

2.5. Span Adjustment ---------------------------------------------------------------------------- 6

2.6. Specification Setting ---------------------------------------------------------------------------- 7

2.7. Internal Count and A/D Count Display ---------------------------------------------- 8

2.8. Specification List (*V1.04) ------------------------------------------------------------------ 8

2.9. System Display Information ------------------------------------------------------------------ 10

3. Main Operation

3.1. System On ---------------------------------------------------------------------------------------- 11

3.2. One Touch Tare ---------------------------------------------------------------------------- 11

3.3. Digital Tare Operation ------------------------------------------------------------------ 11

3.4. Gross / Net Display Toggle ------------------------------------------------------------------ 12

3.5. Weight Unit Conversion ------------------------------------------------------------------ 12

3.6. Counting Operation ---------------------------------------------------------------------------- 12

3.7. Set-Point Setting ---------------------------------------------------------------------------- 13

3.8. Set-Point Alarm Function ------------------------------------------------------------------ 14

4. RS-232C Protocol

4.1. Communication Specs ------------------------------------------------------------------ 16

4.2. Communication Text Command -------------------------------------------------------- 16

4.3. Data Format --------------------------------------------------------------------------------------- 16

4.4. Communication Method ------------------------------------------------------------------ 17

5. Hardware Specification

5.1. Main Components ---------------------------------------------------------------------------- 19

5.2. Block Diagram -------------------------------------------------------------------------------------- 19

5.3. Electronic Connection Diagram --------------------------------------------------------- 19

5.4. Circuitry Diagram ---------------------------------------------------------------------------- 20

DS-425 Service Manual

1. General Specification

1.1. Overall Dimension

1.2. Display Panel

01 General Specification Page No. 1

DS-425 Service Manual

1.3. Main Feature

• Model : DS-425

• Display Resolution : 1/1000, 1/1500, 1/2000, 1/2500, 1/3000, 1/5000, 1/6000,

1/7500, 1/10000, 1/15000, 1/20000, 1/25000, 1/30000

• Internal Resolution : 1/250000, 1/300000

• Capacity : 300g, 600g, 1.5kg, 3kg, 6kg, 15kg, 30kg

• Display Tube : Liquid Crystal (With back-light new design GD-584)

• Weight display : 8 Segment , 6 Digit

• Weigh Unit : 4 Symbol (kg, g, lb., oz.)

• Indicators : 4 Set Point (S1, S2, S3, S4), 8 indicators for Zero, Net, Std,

U.W, U.C, MEM, BATT, PCS

• Interface : RS-232(OPTIONAL)

• Load cell : 300g-K-Type,600g-30Kg N-Type.

• Mechanical Detail : Housing DS-425W, DS-422 Keyboard

• Physical Dimension : (L)321 * (W)256 * (H)80 mm

Platter Size: 105mm x 160mm (300g)

205mm x 250mm (600g Upwards)

1.4. Operation Condition

• Power Source : AC 220V (+10%,-15%) 50HZ/60HZ (Factory Set)

• Temperature : 0°C to 40°C

• Humidity : <85% RH

• Microcomputer : Atmal AT89C52, 8bit

• Display Device : Liquid Crystal Display (With back-light GD-584)

• LCD Display Drive : NEC uPA7225G

• A/D Board : STB-0054 A/D. (DS-422), New A/D Cover

1.5. Main Function

• Basic Weight Unit: g, kg

• Weight Unit Toggle: g, lb, and oz, kg, lb, and oz

• Counting Function

• RS-232C communication

01 General Specification Page No. 2

DS-425 Service Manual

1.6. Layout and Function

1.6.1. Key Sheet and Function
a) Key Layout

b) Key Function

Key Function

[On/Off] For turning the scale ON and OFF
[Re-

Zero]

Resetting the scale to zero.

[Tare] For setting & clearing tare value.
[Mode]

Used to entry into the following modes: Weighing mode or

Counting mode.
[Enter] Used for storing the data.
[Shift] Used to change digital position.

[INC]

1) Used for increase data value when digit blinking;

2) Switch the weight unit.

1.6.2. Display
a) Layout

b) Indicators

Indicator Function

->0<-

Light when display is zero and stable

NET

Light when displays net weight

~

Light when weight is stable

U.C

Light when working in counting mode

SAF

Set-point ALAME Mode is ”ON”, and during Fill Application

SAC

Set-point ALAME Mode is “ON”, At Check Weight Application

01 General Specification Page No. 3

DS-425 Service Manual

3. Main Operation

3.1. System On

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

dS-425 Model Name
Ur. 1.00 Software Version
000000 Segment Checking
111111

999999

Press [On/Off] [On/Off]

0.0000 kg B B Weighing Mode

3.2. One Touch Tare

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable

0.0000 kg B

B

Weighing mode

Load tare
weight on

1.2220 kg

B Weight display

Excute tare [Tare]

0.0000 kg

BB

Net display

Load more
weighing

1.0000 kg

BB

Remove all
items

-1.2220 kg B B B

Minus tare weight

Tare clear [Tare]

0.0000 kg B

B

Weighing mode

Note: This operation is based on No Auto TARE CLEAR, SPEC10 BIT1=0.

3.3. Digital Tare Operation

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000

kg B

B

Weighing mode

Enter into tare
setting mode

[Shift] 0.0000

kg B

B

Right digit is blinking

Set tare value

[Shift]
[Shift]

[INC]

0.00100

kg B

B

Tare weight set

Excute tare [Tare] -0.00100

kgBBB

Minus tare weight

Tare clear [Tare] 0.0000

kg B

B

Weighing mode

Note: This function is available when SPEC10 BIT2=1 only.

03 Main Operation Page No. 11

DS-425 Service Manual

3.4. Gross / Net Display Toggle

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000 kg B B Weighing mode
Load weight

(eg.0.6000kg)

0.6000 kg B Gross weight display

Excute tare [Tare] 0.0000 kg B B Net display
Toggle [INC] 0.6000 kg B Gross Weight display
Remove item 0.0000 kg B B Weighing mode
Toggle [INC] -0.6000 kg B B B Net weight
Tare clear [Tare] 0.0000 kg B B Weighing mode

Note: The function is available when SPEC11 BIT0=1 only.

This function will be unavailable when Weight Unit Conversion function is enabled.

3.5. Weight Unit Conversion

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000

k
g

B

B

Weighing mode

Load weight
(eg.0.6000kg)

0.6000

k
g

B

Convert [INC] 1.3225 lb B Pound display
Convert [INC] 21.165

o
z

B Ounce display

Convert [INC] 0.6000

k
g

B Basic unit display

Remove items 0.0000

k
g

B

B

Weighing Mode.

Note: This operation is available when SPEC15 = 0100 or 1100 only.

3.6. Counting Operation

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000 kg B B Weighing mode
Press [MODE] [Mode] Add 32 B Sample number 32
Change number [Shift][Shift]

Add 32

B 2nd digit selected

Chang value [INC][INC]

Add 52

B Sample number 52

Confirm [*] 0.0000 kg B B B Sample weight
Load 52 samples 0.6000 kg

BB

Weight for all samples

Confirm [*] 52 kg B B Counting mode
Exit [Mode] 0.6000 kg B B Weighing mode

03 Main Operation Page No. 12

DS-425 Service Manual

3.7. Set-Point Setting (SPEC8 BIT0 = 1)

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000 kg B B Weighing mode
Enter into

setting mode

[Mode]
[Mode]

SET-1 Set for Point 1 *1)

Confirm [Enter]

0.0000

kg B Set value

Value change

[Shift]
[INC]

0.0050

kg B

[Shift] key to select
the digit, [INC] key to
change the value of

digit selected *1)
Confirm [Enter] SET-2 Set-Point 1 saved
Point 2 setting [Enter]

0.0000

kg B Set value *2)

Value change

[Shift]
[INC]

0.0100

kg B

Same method as

point 1 setting *2)
Confirm [Enter] SET-3 kg Point 2 saved *3)
Confirm [Enter]

0.0000

kg B Set value *3)

Value Change

[Shift]
[INC]

0.0100

kg B

Same procedure as

point 1 & 2 setting *3)
Confirm [Enter] SET-4 kg Point 3 saved *4)
Confirm [Enter]

0.0000

kg B Set value *4)

Value change

[Shift]
[INC]

0.0100

kg B

Same method as

above *4)

Confirm [Enter] 0.0000 kg B B

Point 4 saved and

back to weighing

mode *4)

Note 1: The indicators S1, S2, S3, S4 will be lighted when setting the corresponding Set-Point.
Note 2: When the weight exceeds the value of Set-Point 1, the indicator S1 will light.

When the weight exceeds the value of Set-Point 2, the indicator S1 and S2 are light.
When the weight exceeds the value of Set-Point 3, S1, S2 and S3 are light.
When the weight exceeds Point 4, S1, S2, S3 and S4 are light.

03 Main Operation Page No. 13

DS-425 Service Manual

3.8. Set-Point Alarm Function

This function has two methods: Filling and Weight Check Method.

3.8.1. Filling Method
Operator fills the item on the platter up to the target weight range. The target range
is determined by 2-set-point (set-point 2 and set-point 3) and continuously fast
alarm will be alert. So operator can know the weight is within the target-weight
range. Set point 1 and set point 2 may be programmed as a fine adjustment range.
The intermediate alarm notes to operator the weight is closed to target weight.

(Near mini. Target) (Mini. Target) (Max. Target)

Zero Set point 1 Set point 2 Set point 3 Set point 4 Full Span

Note: continuous slow alarm continuous fast alarm

3.8.2. Weight Check Method

Operator places item on the platter and check (confirm) whether the weight of the
item is within allowable error range. Basically the allowable error range can be
defined via the setting of 2-set-points (For example: set point 2 and set point 3). And
also you can set the range within point 1 till point 2 and point 3 till point 4 is out of
allowable range. Then the operation can judge the weight error is allowable for not
via the sound of alarm.

(Out of Range) Min.) (Allowable) (Max.) (Out of Range)

Zero Set point 1 Set point 2 Set point 3 Set point 4 Full Span

Note: Continuous slow alarm, Continuous fast alarm

03 Main Operation Page No. 14

DS-425 Service Manual

For Example:

Set-point 1 = 0.0100kg, Point 2 = 0.0200kg, Point 3 = 0.0350kg, Point 4 = 0.0550kg

Indication Flag: B - Bright S - Sparkling

1-ZERO 2-NET 3-STD 4-U.C 5-SAF 6-SAC 7-S1 8-S2 9-S3 10-S4

Indicator

Operation Key Weight

1 2 3 4 5 6 7 8 9 10

Remarks

Weight Stable 0.0000 kg B B Weighing Mode
Press [Enter] [Enter] 0.0000 kg B B B Filling application
Load 0.0150kg 0.0150 kg B B B Fast alarm start
Load 0.0150kg 0.0300 kg B B B B Slow alarm start
Load 0.0150kg 0.0450 kg B B B B B Fast alarm start
Load 0.0150kg 0.0600 kg B B B B B B Alarm off
Remove all item 0.0000 kg B B B
Press [Enter] [Enter] 0.0000 kg B B B Weight check method
Load 0.0150kg 0.0150 kg B B B Fast alarm start
Load 0.0150kg 0.0300 kg B B B B B Slow alarm start
Load 0.0150kg 0.0450 kg B B B B B B Fast alarm start
Load 0.0150kg 0.0600 kg B B B B B B B Alarm off
Remove all item 0.0000 kg B B B B
Press [Enter] [Enter] 0.0000 kg B B Weight check mode

03 Main Operation Page No. 15

DS-425 Service Manual --- V1.04

4. RS-232C Protocol

4.1. Communication Specs

Baud Rate: 2400, 4800, 9600, 19200.
Start Bit: 1
Stop Bit: 1
Data Length: 8
Parity Bit: None

4.2. Communication Text Command

CR The end of data 0DH Termination Code
LF The end of Text 0AH
0 ~ 9 Numeric data (30H~39H)

- (Minus) Minus sign 2DH
. (Period) Period 2EH

Data

, (Comma) Comma 2CH
0 Net Weight 30H Header Code
4 Tare Weight 34H
Null Stable 00H Stable sign
SOH Un-stable 01H

4.3. Data Format

The SPECs to alter the supplement of header code and the status of weight stability
are newly added to specification setting. (Header Code Selection SPEC02 Bit 0,
Weight Stability Selection SPEC02 Bit 1)

4.3.1. Without header-code and weight stable code (Total 17 Bytes)

Net Weight CR Tare Weight CR LF

7 Byte 1byte 7 Byte 1 Byte 1 Byte

4.3.2. Without header-code and with weight stable code (Total 19 Bytes)

Stable status CR Net Weight CR Tare Weight CR LF

1 Byte 1 Byte 7 Byte 1byte 7 Byte 1 Byte 1 Byte

4.3.3. With header code and Without weight stability code (Total 19 Bytes)

Header Net Weight CR Header Tare Weight CR LF

1 Byte 7 Byte 1byte 1 Byte 7 Byte 1 Byte 1 Byte

4.3.4. With header and weight stability code (Total 21 Bytes)

Stable Code CR Hea der Code Net CR Header Code Tare CR LF

1 Byte 1 Byte 1 Byte 7 Byte 1byte 1 Byte 7 Byte 1 B yte 1 Byte

04 RS-232C Protocol Page No. 16

DS-425 Service Manual --- V1.04

e.g.) With Header code and weight stability code

Net weight =-1,2340 Tare weight = 0,450 and weight is stable

Null CR 0 - 0 1 , 2 3 0 CR 4000, 4 5 0 CRLF

Note 1): The data format consists of (header code), minus/plus sign, numeric data and

decimal point. If weight data is minus, -(2DH) is added after header data. If

weight is positive data, 0(30H) is output.
Note2): The data is aligned from right side.
Note3): When weight is over the capacity, the following data is output:

0OV00000CR4???????CRLF (With Header Code)

Note4): By specification setting, the decimal point can be set to period (2EH) or comma

(2CH).

4.4. Communication Method

Communication method can be set as Stream Output, Manual and Command.

4.4.1. Stream Output (Continuously Output)
Data will output to PC side continuously. Please also define the contents of data on
SPEC 03 bit 0&1) is not effective.

4.4.2. Manual Command
Data will output when ↑ key pressed, user may select to output data right away or

hold the command until weight stable by specification setting. If weight is not stable
within certain interval, Error message “ERR C” will appear on the display.

PC Side DS-425 Side

No

X. Seconds

Yes

Text

No

Weight

Manual Command

Yes

Time Out

04 RS-232C Protocol Page No. 17

DS-425 Service Manual --- V1.04

4.4.3. External Command

Data will be output when DS-425 receives the command (ACK 06H) form PC. PC
send a data request signal ACK to DS-425 side, then DS-425 transmits the weight
data to PC after received the request signal, the weight data will be transferred
immediately or hold the command till weight stable. If weight cannot be stable within
the certain interval (set by specification), DS-425 will transmit NAK (15H) to PC.
Note: If ACK signal is sent to DS-425 during digital tare or re-zero operation, NAK

signal will be sent to PC.

PC Side DS-425

ACK

No

Weighing

Yes

Yes

NAK

Yes

X.

Seconds

Stable

NA

K

Data

No

No

EOT

04 RS-232C Protocol Page No. 18

DS-425 Service Manual --- V1.04

5. Hardware Specification

5.1. Main Components

• Microcomputer: ATMAL AT89C52 8 bit

• LCD Display Driver: NEC uPA7225G

• A/D Board: STB-0054, (FOR DS-422), New A/D Cover.

5.2. Block Diagram

A/D BLOCK
STB-0054-3

LOADCELL BLOCK

INTERNAL

MAIN BOARD BLOCK

STB-0052-4

(WITH OPERATE DISPLAY)

POWER
BLK AX

5.3. Electronic Connection Diagram

RS-232

Interface

Operator Display

Display Driver

Keyboard

Main CPU AT89C52 (MCS51)

A/D Block

STB-0052-3

Scale

Internal Block

Interface

Driver

Power

Block

AC Input

05 Hardware Specification Page No. 19

DS-425 Service Manual --- V1.04

5.4. Circuitry Diagram

Please See Attached Pages for

DS-425 Circuitry Diagram

Technical Service Dept.

Shanghai Teraoka Electronic Co., Ltd.

05 Hardware Specification Page No. 20