LOAD CELL AMPLIFIER
MODEL

ＬＡ－１０３１Ａ

OPERATION MANUAL

5
6
7
8
9
10
11

13
14

E

12

EXC
H
MH
ML
L
Filter
10
5
2
GAIN
Z L
curr fine
S
15
16
AZ 17
18
AZR 19TARE CHECK

10V
5V
2.5V

ON

C
F
C
F

ZERO

4

POWER

SPAN

3

LA-1031A

H

RANGE

2

+EXC +SEN -SEN -EXC +SIG -SIG SHL Vout COM Iout COM

1

AZ
SET
SHL

TOYO SOKKITOYO SOKKI CO.,LTD.
Head Office: 964-24 Nippa-chou, Kouhoku-ku, Y o k o h a m a , 2 23 - 00 57 Ja pa n
ＴＥＬ +81-45-540-8353
ＦＡＸ +81-45-544-8354

MA4-00294-R0 (2020/9)

－－ Table of contents －－Page§ １ ． Su m m a r y . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3§ ２ ． A p pe a r a n c e a n d E a c h n a m e . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4§ ３ ． O pe r a t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
３－１）
３－２）
３－３）
３－４）
３－５）
３－６）
３－７）
３－８）

E XCITATION SELECT SWITCH ( SLIDE SWITCH 10V, 5V, 2.5V) ..................................... 5
TARE ( INITIAL T ARE SETTING , 16 POSITION ROTARY SWITCH ) ..................................... 5
ZERO (Z ERO POINT ADJUSTMENT TRIMMER ) .......................................................... 5
GAIN MODE, RANGE (A MPLIFICATION RANGE DIP SWITCH ) ...................................... 6
SPAN (SPAN ADJUSTMENT TRIMMER ) ................................................................. 7
CHECK (P SEUDO INPUT SIGNAL SETTING ROTARY SWITCH ) ......................................... 7
FILTER (C UT OFF FREQUENCY OF ANALOG FILTER ) .................................................. 7
R EMOTE SENSING FUNCTION ............................................................................ 7§ ４ ． C a li br a t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
４－１） N ECESSARY SETTING PRIOR TO CALIBRATE ............................................................ 8４－２） C ALIBRATION METHOD WITH ACTUAL LOAD ............................................................ 8§ ５ ． Tr o u b le sh o o t i n g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
５－１）
５－２）
５－３）
５－４）
５－５）
５－６）

B ASIC CHECK POINT ..................................................................................... 9
W HAT TO DO IF THE DESIRED CALIBRATION IS NOT ACHIEVED ....................................... 9
F INE TUNING OF ZERO AND SPAN OF CURRENT OUTPUT ............................................... 9J UDGEMENT IF THIS UNIT IS MALFUNCTION .......................................................... 10
C HECK L OAD C ELL ..................................................................................... 10
O UTPUT DOESN ’ T BECOME ZERO EVEN IF AZ SWITCH IS PUSHED .................................. 10§ ６ ． I n st a l l a t i o n a n d c o n n e c t io n m e t h o d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2
６－１） I NSTALLATION ENVIRONMENT , ETC . .................................................................. 12６－２） T ERMINAL CONNECTION ............................................................................... 12６－３） T O OBTAIN STABLE MEASUREMENT ................................................................... 14§ ７ ． Li s t o f M o d e ls a n d A c c e ss o r ie s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5７－１） M ODEL .................................................................................................. 15７－２） A CCESSORIES ........................................................................................... 15§ ８ ． S pe c if ic a t i o n s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 6
８－１）
８－２）
８－３）
８－４）

P OWER SUPPLY PART FOR L OAD C ELL ................................................................ 16
A MPLIFIRE PART AND I/O PART ....................................................................... 16
A NALOG A UTO Z ERO FUNCTION ....................................................................... 17
G ENERAL ................................................................................................ 18§ ９ ． D im e n si o n a l Dr a w in g . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9§ １ ０． Fu n ct i o n a l b l o c k d ia g r a m . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 9§ １ １． Ti m in g c h a r t o f A u t o Ze r o ( A Z) o p e r a t io n . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 0This document is translated from MA4-00280-R1 (Japanese)

MA4-00294-R0-2-

§１．Summary
This unit is a low drift instrumentation amplifier which amplifies signal from a strain gaugetransducer and outputs voltage signal 0～±5V and current signal 4～20mA.
This unit has analog Auto Zero function which set output signal to zero by a button switch or
external command input.
Applied voltage to Load Cell or a sensor is selected from 10V, 5V, 2.5V by a slide switch.
Frequency characteristic is selected by two slide switches.
Also this unit has a remote sensing function to reduce measurement error caused by asensor cable.
The power supplied voltage is AC 85～264V as standard or DC20～27V as option, which
specified as option at the time of order .
DC/DC converter in this unit isolates power supplied voltage from current / voltage output
signal.

MA4-00294-R0-3-

§２．Appearance and Each nameAppearance of this unit

5
6
7
8
9
10
11

13
14

E

12

EXC
H
MH
ML
L
Filter
10
5
2
GAIN
Z L
curr fine
S
15
16
AZ 17
18
AZR 19TARE CHECK

10V
5V
2.5V

ON

C
F
C
F

ZERO

4

POWER

SPAN

3

LA-1031A

H

RANGE

2

+EXC +SEN -SEN -EXC +SIG -SIG SHL Vout COM Iout COM

1

AZ
SET
SHL

TOYO SOKKI① POWER (LED)LED for indicating power ON② CHECK (CAL SW)

Pseudo signal generation switch, 16 position rotary switch③ TAREFor Tare subtraction, 16 position rotary switch④ ZERO(C,F)

Zero adjustment trimmer (Coarse / Fine:15 rotation)⑤ SPAN(C,F)

Span adjustment trimmer (Coarse / Fine:15 rotation)⑥ GAIN MODE

Low/High (input signal≧0.6mV/V: Low,

⑦ RANGE

Amplification range adjusted by a DIP switch (5 steps setting)⑧ TERMINAL (5mm pitch)

External command input of AZ and answer back signal of SET⑨ EXCITATION VOLTAGE

Select excitation voltage by a slide switch (10V, 5V, 2.5V)⑩ FILTER 1st

Select the range of cut off frequency by a slide switch(L:1Hz, ML:10Hz, MH:100Hz, H:1kHz)⑪ FILTER 2nd

Select a multiple of cut off frequency (x2, x5, x10) by a slide switch⑫ FINE-TUNE of CURRENTOUTPUT (Z,S)

Fine adjustment trimmer for Zero and Span of current output⑬ AUTO ZERO

Button switch and status LED of Auto Zero

⑭ AUTO ZERO RESET

Button switch of canceling Auto Zero

0.6mV/V: High)⑮ TERMINAL(7.62mm pitch) 14pin terminal for Load Cell, Analog output and Power line
⑯ MOUNTING HOLE

Fixing hole 2 -Φ4.5mm

MA4-00294-R0-4-

§３．Operation
This unit outputs voltage signal and current signal simultaneously. Voltage output is bipolarand can be output up to ±5V. (Max. ±10V depending on the intensity of input signal from asensor)Current output 4 ～20mA is available only when voltage output is set to 0 ～5V. Combination
other than 4～20mA / 0～5V is impossible.
３－１） Excitation select switch (slide switch 10V, 5V, 2.5V)
This switch enable to change an applied voltage to Load Cell or a sensor.
Before calibrating this unit, check the specification of Load Cell and apply an appropriate
excitation voltage to Load Cell. Changing excitation voltage can correct sensitivity of this unit
automatically, but there is an error to consider.
When changing excitation voltage from 10V to 5V or 2.5V, amplification of this unit can becorrected 2times, 4times respectively. An error of sensitivity against the previous value is up
to 2% when changing excitation voltage. After calibration of this unit has done, changing
excitation voltage, calibration value of zero and span will be modified slightly. So r ecommend
to calibrate again.
３－２） TARE (initial Tare setting, 16 position rotary switch)
This switch can be used to cancel an unbalanced voltage equivalent to Tare amount when
Tare amount is too large to achieve zero adjustment. The setting is 16 positions from 0 to F
and can be set at about 0.15mV/V step. (0 to 2.25mV/V) The larger the setting value, thelarger Tare cancellation amount.
When adjusting the output to 0V or 4mA (with Tare load applied), set a coarse [ZERO]
trimmer at the center position beforehand and turn a [TARE] rotary switch to set the output
value to the closest of 0V or 4mA.
If a weight of Tare load is known in advance, equivalent output level of Load Cell weighing
Tare load can be calculated using the following formula to determine the code of TARE rotaryswitch.
Equivalent LC output of Tare (mV/V)＝

Tare load weight
Load Cell rated capacity

×Load Cell rated output (mV/V)

Code and Tare amount by [TARE] rotary switch
Code０

Tare amount
0
mV/V

Code
４

Tare amount
0.6
mV/V

Code
８

Tare amount
1.2 mV/V

CodeC

Tare amount
1.8 mV/V

１

0.15 mV/V

５

0.75

mV/V

９

1.35 mV/V

Ｄ

1.95 mV/V

２

0.3

mV/V

６

0.9

mV/V

Ａ

1.5

mV/V

Ｅ

2.1

３

0.45 mV/V

７

1.05

mV/V

Ｂ

1.65 mV/V

Ｆ

2.25 mV/V

mV/V

３－３） ZERO (Zero point adjustment trimmer)
This is a zero adjustment trimmer to set the output voltage to 0V or 4mA when there isunbalance voltage of Load Cell or voltage of Tare load. There are a coarse adjustment
trimmer and a fine adjustment trimmer.
Adjustment range of zero trimmer is approximately ±0.2mV/V.
If zero adjustment cannot be achieved within this range, use a [TARE] rotary switch.
MA4-00294-R0-5-３－４） GAIN MODE, RANGE (Amplification range DIP switch)
Set the amplification range of a [SPAN] adjustment trimmer according with the output
voltage of Load Cell or sensor.
Amplification range is adjustable in 10 steps by combining [GAIN MODE (H/L)] and [RANGE(1～5)] DIP switch. Set only one bit of the [RANGE(1～5)] DIP switch. Amplification will belarger as a range number becomes larger. Appropriate setting of [GAIN MODE] and [RANGE]
is determined by the following formula. Please refer the table below.
※When span amount of output of Load Cell is 0.6 to 3.3mV/V, set GAIN MODE=L.
When it is 0.15 to 0.6 mV/V, set GAIN MODE=H.
※If output voltage is set to 10V, [GAIN MODE] should be set to H.
LC output of maximum load (mV/V)＝

Required amplification ＝Maximum load
Load Cell rated capacity

×Load Cell rated output (mV/V)

Desired output voltage at maximum load (mV)
Load Cell output of maximum load (mV/V) x EXC (V)※EXC is applied voltage to Load C ell = 10V, 5V or 2.5V

GAIN
MODE

L

H

EXC=10V

EXC=5V1149～ 236

298～ 472596～

2209～ 330

418～ 660

836～ 1320

Necessary LC output
amount (mV/V)
for 5V,20mA
for 10V
outputoutput
3.36～2.12―――
2.39～1.52―――

3299～ 472

598～ 944

119～ 1888

1.67～1.06――――――

Amplification

RANGE
(1～5)

EXC=2.5V
944

4418～ 661

836～1322

1672～ 2644

1.20～0.76

5598～ 944

1196～1888

2392～ 3776

0.84～0.53

1598～ 944

1196～1888

2392～ 3776

0.84～0.53―――
3.36～2.12

2837～1316

1674～2632

3348～ 5264

0.60～0.38

2.39～1.52

31195～1879

2390～3758

4780～ 7516

0.42～0.27

1.67～1.06

41673～2631

3346～5262

6692～10524

0.30～0.19
0.21～0.13

1.20～0.76

50.84～0.53
2390～3759
4780～7518
9560～15036
Numeric values in above table are typical value. They have an error up to 1% becauseof resistance tolerance in a circuit.
If this unit is shipped combined with a weighing scale which is adjusted together, no need tochange GAIN MODE nor RANGE.
If this unit is shipped alone, GAIN MODE=L and RANGE=4 are set as for reference sensitivity,
1mV/V input and 5V output, at the time of shipment.

!CAUTION
Reference sensitivity of this unit is specified as 1mV/V input and EXC=10V. If input signal issmall, amplify it larger by setting GAIN MODE and RANGE higher, but it leads to side effects.
First, it worsens temperature characteristic of zero point of output. Second, it worsens
fluctuation of output signal. Noise level of amplifier of this unit is 0.5mVp -p of 5V output. If
amplifying larger, noise level is also amplified, it leads to fluctuate the output obviously.
MA4-00294-R0-6-

Filter setting also affects fluctuation of the output signal. Noise level of the output signal islarger about 4 times at 100Hz and about 10 times at 7kHz compared to 2Hz. But it depends
on the connected equipment for measuring the output signal of this unit.
３－５） SPAN (SPAN adjustment trimmer)
This is a span adjustment trimmer for amplifying incoming signal. There are a coarse
adjustment trimmer and a fine adjustment trimmer.
Rotate a trimmer clockwise (CW) to increase amplification, counterclockwise (CCW) todecrease it. Rotate a coarse adjustment trimmer fully counterclockwise (CCW) can reduce
the output to about 70% of the maximum.
If adjustment cannot be completed within this range, change the [GAIN MODE (L/H)] and[RANGE(1～5)] DIP switch setting.
３－６） CHECK (Pseudo input signal setting rotary switch)(Pseudo input signal generating push switch)
By pressing a [CHECK] button switch, a pseudo input signal can be generate d and added tothe input signal. A pseudo input signal is generated only while the push switch is pressed.
The pseudo input signal can be set at about 0.15mV/V step by 16 position rotary switch.
After calibration of the scale is completed, with no load (output is 0V or 4mA), pressing a[CHECK] push switch (keep pressing) and turn a [CHECK] rotary switch to set the output tobe 75% or more of measured value of the maximum load. By making a note of the rotaryswitch setting position and output value, it can be used as a secondary calibration value.
Even if the span trimmer is touched after calibration, the span amount can be re -calibrated
based on this secondary calibration value.
３－７） FILTER (Cut off frequency of analog filter)
Two slide switches determine the cut off frequency of analog filter to r esponse incoming
signal.
First slide switch (L,ML,MH,H)
H
Response quickly (cut off frequency is higher)
MH
ML
L
Response slowly (cut off frequency is lower)

Tend to fluctuate output

Tend to be stable output

Second slide switch (x2, x5, x10) is used for a multiple of cut off frequency.
Cut off frequency ( −3dB, analog filter) combined with two slide switches as below.
Cut off frequency
L
ML
MH
H
x2
2Hz
20Hz
200Hz
2kHz
x5
5Hz
50Hz
500Hz
4.5kHz
x10
10Hz
100Hz
1kHz
7kHz
３－８） Remote sensing function
When using a longer Load Cell or sensor cable, resistance of the cable is not negligible and its
resistance vary if environment temperature vary. Fluctuation of resistance will cause
fluctuation of voltage drop and fluctuation of applied voltage to a sensor and result inmeasurement error.
Remote sensing function helps to decrease a measurement error. This function requires asensor cable of 6core wire. If 4core wire cable is used , set two attached metal plates as they
are at the time of shipment. If 6core wire cable from Load Cell with remote sensing is used,remove two metal plates from terminal and make a remote sensing function effective.
MA4-00294-R0-7-

!CAUTION
In case of not using a remote sensing function, make it sure to set two attached metal plates
to make electrical short between +SEN and +EXC terminal also between -SEN and -EXC
terminal. Otherwise a remote sensing circuit in this unit does not work correctly and will
abnormal voltage is applied to a sensor and might damage a sensor of Load Cell or this unit.

§４．Calibration
Calibrate the output level to 0V with no load on Load Cell, and calibrate the output levelto the desired voltage with maximum load on Load Cell. Current output 4 ～20mA isavailable when voltage output is adjusted to 0 ～5V. Calibration operation is based on“actual load calibration” using a known weig ht such as a reference weight.
４－１） Necessary setting prior to calibrate
1). Select appropriate excitation voltage from 10V, 5V or 2.5V according to thespecification of applied voltage of Load Cell.
(Make sure to select before calibration, otherwise measurement error occurs andre-calibration will be needed)2). Select appropriate filter setting (L,ML,MH,H ,x2, x5, x10)
Cut off frequency is select ed from 2Hz to 7kHz, 12 frequencies.
3). Amplifier gain setting (GAIN MODE, RANGE setting)Set the amplification range for the desired output level. Calculate Load Cell output of
maximum load and select the corresponding GAIN MODE(H/L) and RANGE (1～5).
For a calculation method of Load Cell output of maximum load, refer to section 3-4).
4). Make sure to [AZ] LED is turned OFF
Push [AZR] button for 3 seconds to cancel auto zero if turned ON.
４－２） Calibration method with actual load1). Put nothing on Load Cell (only the initial Tare load is applied)2). Turn a [TARE] rotary switch to the position where the output is closest to 0V or 4mA.
3). Turn a [ZERO] trimmer (Coarse, Fine) to adjust the output to 0V or 4mA.
4). Put a known weight such as a reference weight on Load Cell and turn a [SPAN] trimmer(Coarse, Fine) to adjust to the desired output voltage or current.
5). Remove a known weight such as reference weight from Load Cell.
6). Confirm that the output is 0V or 4mA. If not, repeat from step 3) above.
!CAUTION
Current output 4～20mA is available when voltage output is adjusted to 0～5V. When using
voltage output and current output simultaneously, c alibration of voltage output has priory
and should have been done first . After calibration, if there is an error of 4mA or 20mA ofcurrent output, use a f ine adjustment trimmer ‘curr fine(Z,S)’ for zero and span of current
output, please refer to 5-3).
When only using current output, calibrate current output directly using of ZERO andSPAN adjustment trimmer.
If calibration operation cannot be done properly, refer to section §5 Troubleshooting andtake measures.

MA4-00294-R0-8-

§５．Troubleshooting
If this unit is malfunctioning, please contact us if the problem cannot be solved by thefollowing measures. At this time, please inform us of the model name, product serial number,the malfunction symptoms and usage as much as possible. The model name of Load Cell ora sensor connected to this unit should be also informed.
５－１） Basic check point
1). Check whether the power supplied voltage (AC85 to 264V or DC20 to 27V) is normal and stable2). Check whether the terminals are connected correctly and firmly５－２） What to do if the desired calibration is not achieved1). Zero adjustment cannot be done.
Zero adjustment range is ±0.2mV/V
If the output is more than 0V even if a [ZERO] trimmer is turned fully counterclockwise(CCW), increase a [TARE] rotary switch setting.
If the output is less than 0V even if a [ZERO] trimmer is tuned fully clockwise (CW),
decrease a [TARE] rotary switch setting.
2). When span adjustment, the desired output voltage cannot be set.
If the output goes below the desired value even if a [SPAN] trimmer is turned fully clockwise(CW), change a [GAIN MODE] and [RANGE] DIP switch and increase the amplification by
one step.
If the output exceeds the desired value even if a [SPAN] trimmer is turned fully
counterclockwise (CCW), change a [GAIN MODE] and [RANGE] DIP switch and decrease
the amplification by one step.
10 steps can be set according to the [GAIN MODE] and [RANGE] DIP switch setting. If thedesired output is not obtained even if all the DIP switch setting, check whether Load Cell
output satisfies the sensitivity adjustment range of this unit.
Choose only one step of the setting of [RANGE (1～5)]
3). Output voltage is out of range of ±10V or output current is out of range of 4～20mA
even though it is not overloaded.
① When a part of Load Cell cable is disconnected. (Ref: Section 5-5)
② A [TARE] rotary switch setting is inappropriate. (Ref: Section 3-2)
③ A [GAIN MODE] or [RANGE] DIP switch setting is inappropriate. ( Ref: Section 3-4)
④ When Load Cell becomes defective. (Ref: 5-5)５－３） Fine tuning of zero and span of current output
Current output 4～20mA is available when voltage output is set to 0～5V. A fineadjustment trimmer ‘curr fine(Z,S)’ is adjusted at the factory. If re-tuning of current
output is necessary when outputting voltage and current simultaneously and connected
equipment has an error for measuring voltage and current, take measures as follows. But
combination other than 0～5V/4～20mA is impossible.
There are two adjustment trimmers on the front panel.
curr fine (Z) : Zero adjustment trimmer of current output ( 1 rotation )Adjust this trimmer to 4mA when output voltage is 0V
curr fine (S) : Span adjustment trimmer of current output (1 rotation )Adjust this trimmer to 20mA when output voltage is 5V
MA4-00294-R0-9-

Current output is adjusted properly at the shipment in our factory. It is not necessary to
re-adjust it. But when current output is not appropriate even if re-adjusting has been
done, please contact us.
５－４） Judgement if this unit is malfunction1). Check the excitation voltage of Load Cell
Checking the excitation voltage between terminal No.1 (+EXC) and No.4 (−EXC) is stable
at 10V, 5V, 2.5V, tolerance ±5% respectively. If it is not stable, a power supply circuit
inside this unit may be defective.
If excitation voltage exceeds 10V, such as 12V, check the connection of remote sensing
wire. If 4 core cable is used from Load Cell, it should make electrical short between +SEN
and +EXC terminal also between −SEN and −EXC terminal. Otherwise excess voltage isapplied to Load Cell.
2). Short the output voltage of Load Cell (making an electric short between terminal No.5(+SIG) and No.6 (−SIG)). In other words, the input voltage to this unit is made zero.
At this time, set a [TARE] rotary switch to ‘0’ once. In this state, the voltage which
adjusted by a [ZERO] trimmer is output, so the output does not bec ome 0V, but it can bechecked whether the output is stable.
If it is not stable, an amplification circuit in this unit may be defective. If it is stable, check
Load Cell side.
Please restore the setting of a [TARE] rotary switch to the previous position after checking.
５－５） Check Load Cell
Since Load Cell is composed of a bridge circuit, it is possible to make a rough judgement
by measuring the input / output resistance and insulation resistance.
＊ Please be sure to turn power OFF of this unit before checking Load Cell.
1). Failure judgement method by Load Cell resistance value.
① Remove all Load Cell cables.
② Measure the bridge resistance of Load Cell with a tester and check if there is any
abnormality in the input / output resistance.
2). Failure judgement method based on Load Cell insulation resistance① Remove all Load Cell cables.
② Measure the insulation resistance between shield and each cable of Load Cell at
a voltage within 50V.
In addition, the insulation resistance between a metal case of Load Cell and each cable
other than shield is also measured at a voltage within 50V .
③ If the insulation resistance is 1000MΩ or more, Load Cell is mostly good.
５－６） Output doesn’t become zero even if AZ switch is pushed1). Output won’t be changed and [AZ] LED is blinking
When output voltage exceeds ±2.0V before pushing a [AZ] button or inputting [AZ]
command, ignore Auto Zero and blink [AZ] LED as an error. However this unit isoperated normally as before.
When ignoring [AZ] command, no answer back [SET] is transmitted, it is able to judge
an error at the external controller side.
Blinking [AZ] LED will be stopped after pushing a [AZR] button or operating Auto Zerosuccessfully within the range of output ±2.0V.
MA4-00294-R0- 10 -

2). Output won’t be 0V or 4mA completely
Circuit of Auto Zero have been adjusted in the factory, there is no need to re -adjust it
after shipment. If re-adjustment is needed because the connected equipment has anerror for measuring voltage and current, take following measures to adjust. If output
doesn’t become zero even if after adjustment has done, please contact us.
If residual voltage or current is large after AZ operation, take measures as follows.
① Put nothing on Load Cell (only the initial Tare load is applied) and check zero output.
Operate zero calibration if needed.
② Turn power OFF once.
③ Turn power ON while [AZ] button is pushed. Enter zero adjustment mode of AZ. Starts
to blink [AZ] LED.
④ Push [AZ] button to increase the output and push [AZR] button to decrease theoutput. Set output to 0V or 4mA using the two buttons.
⑤ Turn power OFF and turn ON again without pushing any button.
After above adjustment has been done, put nothing on Load Cell and push [AZ] button.
Check the output voltage is within ±2mV or the output current is within 4mA±6.4μA
while [AZ] LED is turned ON.
Next, put a load on Load Cell and set the output larger within the range of Auto Zero.
(i.e. 2.0V). Push [AZ] button and check the output become 0V or 4mA.
If residual voltage or current is large compared the one when operating AZ with no load,
proceed to the following measures.
① Push [AZR] button and cancel Auto Zero. Put a load on Load Cell and set output
voltage to 1.5V to 2.0V or set current output to 8.8mA to 10.4mA. Turn power
OFF once.
It is possible to use [CHCEK] button and [CHCEK] rotary switch instead of putting
a load on Load Cell. But in this case, keep pushing [CHCEK] button.
② Turn power ON while [AZR] button is pushed. Enter span adjustment mode of AZ.
Starts to blink [AZ] LED. But blinks faster than ze ro adjustment mode of AZ.
③ If output doesn’t become 0V or 4mA, push [AZ] button to increase the output andpush [AZR] button to decrease the output. Set output 0V or 4mA using the two
buttons.
Use [CHCEK] switch as substitution of a load, keep pushing [CHCEK] button.
④ Turn power OFF and turn ON again without pushing any button.
After above adjustment has been done, put /remove a load on Load Cell and push [AZ]
button. Check the output voltage is within ±2mV or the output current is within 4mA±
6.4μA while [AZ] LED is turned ON.

MA4-00294-R0- 11 -

§６．Installation and connection method６－１） Installation environment, etc.
1)
2)

3)

The operating temperature range of this unit is 0 ℃ to 40℃.
Consider installing in a place not exposed to the direct sunlight.
This unit is operated with power supplied voltage AC85V to 264V as standard, or DC20V
to 27V as option.
Note that connecting to a different voltage may cause failure or damage.
Please fix this unit with M4 screw using hole 2-Φ4.5 of the base bracket.

６－２） Terminal connection
Wiring to this unit is done with 7.62mm pitch 14pin terminal block. The shield line of eachcable shall be grounded by either this unit or each connected instrument, so that there is no
ground loop.
1). Load Cell, Analog output and Power line connection
7.62mm pitch terminal block
No.
1

+EXC

Connection signal
Excitation voltage to Load Cell (+)

2

+SEN

Remote sense input

(+)

3

－SEN

Remote sense input

(－)

4

－EXC

Excitation voltage to Load Cell (－)

5

+SIG

Input signal from Load Cell (+)

6

－SIG

Input signal from Load Cell (－)

7

SHL

Shield line of Load Cell cable

8

Vout

Voltage output signal (＋)

9COM

Voltage output signal (－)

10

Iout

Current output signal (＋)

11

COM

Current output signal (－)

12EGrounding

13

AC

14

AC

AC85V to 264V
(standard)

+24V
0V

COM(#9, #11) arecommon.
The shield line ofthe output signal
should be groundedon the receiving
device side.

DC20V to 27V (option)
DC0V (option)

Applicable crimp terminal: Crimp terminal for M3 up to 6mm width2). Control I/O connection
5mm pitch screw-less terminal block
No.
Connection signal
15
16
17

AZ

Auto Zero command (contact input)

SET-C

Answer back output ( Corrector )

18

SET-E

Answer back output ( Emitter )

19

SHL

Shield line of I/O control cable

Applicable wire range
Single wire = Φ0.4～1.2mm (AWG26～16)
Strand wire = 0.2～0.75mm 2 (AWG24～20),
Standard peeled wire length: 11mm

wire OD ≧Φ0.18mm

MA4-00294-R0- 12 -

3). Precautions for connection① Terminal of +EXC and +SEN /−EXC and −SEN is connected by two metal plates at thetime of shipment. If using a 4-core Load Cell cable and not using remote sensing
function, make it sure to two attached metal plates are connected as they are at thetime of shipment. If using a 6-core Load Cell cable, remove two metal plates fromterminal and make remote sensing function effective.
② Remote sensing of this unit is effective when a resistance of Load Cell cable less than10Ω (20Ω, cable length to and from). General AWG24 wire of 100m length has aresistance about 9Ω. Use a Load Cell cable as thick as possible.
③ Ground the shield line of each cable on either this unit or the connected instrument. If
connected instrument doesn’t have a terminal of shield, make a use of terminal #12(E)of this unit.
④ Since cable wiring color of Load Cell (a sensor) differs depending on the manufacturer,
check the wiring color with Test Report attached to Load Cell.
⑤ In general Load Cell, shield line of Load Cell cable is not connected to a metal case of
the Load Cell. If the ground potential of this unit is different from the potential of Load
Cell metal case, it is easy to be affected by inductive noise.
Therefore, make sure that Load Cell mounting base is at the same potential as metal caseof this unit by a grounding cable.
⑥ Regarding of length of analog output cable, it depends on surrounding electromagnetic
circumstances, voltage output cable length should be shorter than 5m.

MA4-00294-R0- 13 -

６－３） To obtain stable measurement
When a sensor of strain gauge (i.e., Load Cell, Pressure gauge) is amplified by an amplifier oris connected to an indicator, the value may fluctuate or may not be stable.

Control Unit
(PLC, etc.)

SensorIndicator, Amplifier(LA-1031A, etc.)( Fig. 1 )This is because of difference of an electric potenti al between a sensor part and an amplifier /indicator part. It is induced from electricity rounding of general commercial power supply(AC100V/AC200V).

( Fig. 2 )The most effective way to improve stability is to use a cable to connect an Earth terminal of anamplifier / indicator to a case or chassis of sensor, like Fig 2.
If it is difficult to find an Earth terminal of sensor side, loose bolt of metal case of sensor andconnect the cable. Please make the electric potential be same as possi ble.
In case that a sensor and amplifier / indicator have installed apart separately, stability
improves when an Earth terminal of indicator / amplifier and metal case of sensor connect tothe nearest earth of each. But if they are apart far from each oth er, it may not bring a goodresult due to different electric potential of the earth. However, in such a case, stability
improves if connecting a cable as Fig 2.

MA4-00294-R0- 14 -

§７．List of Models and Accessories

７－１） Model
ＬＡ－１０３１Ａ－ＤＣ

Po w e r su pp lie d v o lt a g e
Bla n k ： A C 85 t o 26 4 V
DC： D C2 0 t o 2 7 V ( O pt io n )Pr o du ct m o de l n a m e７－２） Accessories
Metal plate for shorting
Operation Manual

2 pcs (attached to the terminal)
1 copyMA4-00294-R0- 15 -

§８．Specifications
８－１） Power supply part for Load Cell
1). Excitation Voltage

DC10V, 5V, 2.5V±5％ (selective at a switch on rear panel)

2). Number ofConnectable sensors

4 sets of 350Ω type Load Cell

3). Correction ofvoltage drop

Remote sensing function
Resistance of Load Cell cable (to and from) should be less than 20 Ω
(equivalent to AWG24 wire x 100m)

８－２） Amplifire part and I/O part1). Input range±3.3mV/V (sum of tare amount and span amount)2). Initial tareelimination

0 to 2.25mV/V(0.15mV/V step by 16 position rotary switch)3). Zero adjustment

Range approx. ±0.2mV/V
Multi-turn trimmer adjustment (Coarse, Fine adjustment :15 rotations each)4). Auto Zero

Range ±2.0V
When output is within the above range after zero adjustment andinitial tare elimination, set output to 0V if operating Auto Zerofunction.
[AZ] button or external [AZ] command enables Auto Zero.
[AZR] button cancels Auto Zero.

5). Sensitivity
adjustment

Amplification variable range: x 3333 to x151 (EXC=10V)
Span amount 0.15 to 3.3mV/V can output 4～20mA or 0～5V
(If span amount is 0.6mV/V or more, 0 to 10V can be output)
Standard sensitivity: Output 0～5V or 4～20mA when EXC=10V,
0～1mV/V input
H (0.15 to 0.6mV/V) / L (0.6 to 3.3mV/V) (DIP switch)
5 steps (DIP switch)
Multi-turn trimmer adjustment (Coarse , Fine adjustment:
15 rotations each)Gain More
Range
Span
6). Voltage output

0 to ±5V (Load resistance 2kΩ or more) Bipolar output
For spans amount 0.6mV/V or more, output of 0 to ±10V is possible.

7). Current output

4 to 20mA (Load resistance 510Ω or less)(corresponding to voltage output 0 to 5V)

8). Simultaneous output

Output voltage and current simultaneously.
Because zero and span trimmer are common for both output,
there is 0.2% error of conversion of voltage to current.
(two trimmers on front panel are reserved to fine tune zeroand span of current output)9). Non linearity±0.05％FS (±0.1％FS when EXC=2.5V)

10). Filter
Characteristic

Selective from 2Hz to 7kHz, 12 frequencies
Low pass filter, −12dB/oct.
Range switch: L, ML, MH, H
Multiple switch : x2, x5, x10

MA4-00294-R0- 16 -

11). Temperature coefficientZero±0.005％ FS/℃ typ. (at standard sensitivity)(twice the above at EXC=5V, 4 times at EXC=2.5V)

Sensitivity±0.005％ FS/℃ typ.
(±0.01％ FS/℃ typ. at EXC=2.5V)

12). Check function

A pseudo input signal can be generated by pushing [CHECK]
button. It is added to the input signal.
Can be set up to about 2.25mV/V about 0.15mV/V step.
(Temperature coefficient: 25ppm/℃ maximum)

13). Switches

Two button switches[AZ] operates Auto Zero
[AZR] cancels Auto Zero14). External input

One bit (AZ)
One shot Make contact (Pulse width 0.2 second)

DC5V
Auto Zero command

○

470Ω

LA-1031A

Equivalent input circuit
15). Control output

One bit (SET)Open Collector output, negative logic, one bit one common
Isolated by photo coupler, NPN transistor
Collector – Emitter: ON when Make
Rated output: DC30V, 30mA (resistance load)
Saturation voltage between Collector and Emitter: 1.2V or less
Photo coupler, TLP-127, TOSHIBA or the equivalent.
30V max

30mA max

SET output(Pulse width 0.2s)

LA-1031A

Equivalent output circuit８－３） Analog Auto Zero function
1). Auto Zero

Pushing [AZ] button for 3 seconds or external [AZ] input (0.2s
one shot Make pulse) let output voltage within ±2.0V set to
0V. Output increase and decrease amount from that point .
Output should be stable for 0.5second before AZ operation.
[AZ] LED is turned ON while AZ operation
Pushing [AZR] button for 3 seconds cancel Auto Zero
MA4-00294-R0- 17 -

Time length to set AZ
Resolution of AZ
Elimination accuracy
Out of range
operating AZ
Retain of AZ

2). Answer back (SET)

less than 0.2 second
less than 500μV or 1.6μA
less than ±2mV or 6.4μA(maximum residual voltage or current after AZ operation )If output is out of range of ±2.0V, ignore AZ,[AZ] LED starts to blink and keep it until the next successful
AZ operation or pushing [AZR] button for 3 seconds.
Data of AZ is memorized in a non-volatile memory (FeRAM),AZ is kept operating even if this unit is turned power OFF/ON
After input of AZ command, procedure done properly, output[SET] signal for 0.2 second as answer back. (Open Collector
signal)If it is out of operating range of AZ, ignore AZ, doesn’t output[SET] signal. [AZ] LED starts to blink as an error indication.

８－４） General1)． Power stability±0.02％ FS (Power supplied voltage fluctuation within ±10％)2)． Power supplied
AC85 to 264V, 50/60Hz as standard
voltage
DC20 to 27V
as option3)． Current consumption 0.6A typ.(AC100V), 0.4A typ.(AC200V), 0.5A typ.(DC24V)
4)． Operating Temp./Humidity
0～＋40℃、20～85％ R.H. without condensation
5)． Store Temp./Humidity−20～＋60℃、20～85％ R.H. without condensation
6)． Mass
approx. 0.7kg
7)． Mounting method
Wall mount method
Fix with M4 screw using 2-Φ4.5 of the base bracket

MA4-00294-R0- 18 -

§９．Dimensional Drawing

5
6
7
8
9
10

14

+24V 0V

13

TARE CHECK

EXC
H
MH
ML
L
Filter
10
5
2
GAIN
Z L
curr fine
S

C
F
C
F

ZERO

E

3
4

ON

10V
5V
2.5V

SPAN

+EXC +SEN -SEN -EXC +SIG -SIG SHL Vout COM Iout COM

2

LA-1031A
POWER

H

RANGE

11
12

1

15
16
17
AZ
18
AZR 19AZSETSHLTOYO SOKKI

Fixing hole

§１０．Functional block diagram

H:0.15 to 0.8mV/V
L:0.6 to 3.3m V/V(set H: ±10V out put)

Amp.
Range

GAIN MODE

Frequency Selection

Auto Zero

Tare subtraction

Gain adjustment

FilterZero adjustment

SPAN adjustment

fc = 2Hz to 7kHz

Addition(Coarse / Fine)(Coarse / Fine)-12dB/oct.

AmplifierVgrs - Vofs

Amplify correction(15 turn trimmer x4)
L/C power supply
w/ remote sensing
350Ω 4units

A/D converter
Vgrs input

Applying voltage
selection

Auto ZerocommandAnswerback

D/A converter
Vofs output

Buffer Amplifier

Voltage
OutputV/I conversion

Current
OutputI/O controller
Non-volatilememory (Vofs)

1 turn trimmer x2

Auto Zerocommand
Auto Zero Reset command

MA4-00294-R0- 19 -

§１１．Timing chart of Auto Zero (AZ) operation

Maximum time length to respon d AZ (200mse c. m aximum )Start tooperate AZ

OutputAZ command input(0.2s one shot pulse)
500 mse c. minimum

50 ms. min.
60 ms. max .

Required time length of Monitoring
stable output before AZ noise of AZ
command pulse
operation

140 mse c. maximum
Convergent time to out put 0V
after AZ operation

Monitoring output(A/D con version)
Calculate erase volt age base d on th e latest da ta. In thiscase, average 8 data before data2. Calculating time : 8
sampling, about 500msec.
Answer back (SET)(0.2s one shot pulse)

MA4-00294-R0- 20 -