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Load cell amplifier for weighing scale - Serial Output

Complete integrated front end containing amplifier, ADC, Digitizer output at 9600 baud rate output

Sunrom Part# 1190

Available We dispatch same day if ordered by 4PM (excluding holidays), then courier usually takes 2-5 days.
Quantity Pricing
Quantity :
Price (Discount%)
1-4 :
Rs.946/- (0%)
5-9 :
Rs.918/- (3%)
10-24 :
Rs.880/- (7%)
25-49 :
Rs.851/- (10%)
50-74 :
Rs.832/- (12%)
75-99 :
Rs.804/- (15%)
100-249 :
Rs.776/- (18%)
250-499 :
Rs.757/- (20%)
500-999 :
Rs.738/- (22%)
1000+ :
Rs.710/- (25%)

The board is total solution for analog front end for Load Cell applications.

This board is highly integrated in the sense it contains Instrumentation Amplifier, Analog to Digital Convertor and Digitizer which outputs serial data of 9600 baud rate for direct reading in kilograms.

The output can be used to connect to microcontroller for further display and processing Or can be fed to PC serial port to view on terminal.

The calibration functions in built in the board giving very accurate, stable and reliable output every time.

Note for buyers: The use of board is suitable for student projects and research purpose. It will not be suitable for commercial retail application.





Working Voltage


V DC Regulated

Output Reading Rate Every


Mili Seconds

Data Format



UART baud rate (8 bit data, no parity, 1 stop bit)



Board Pinouts for Interfacing


Pin Name



Receive Input

Input serial data of 5V logic level to perform forced calibration or auto zero, Usually connected to TXD pin of microcontrollers/PC/RS232.


Transmit Output

Output serial data of 5V logic level, Usually connected to RXD pin of microcontrollers/PC/RS232.


Power Supply

Regulated 5V supply input.



Ground level of power supply. Must be common ground with microcontroller.

Data Format

The output of data from sensor is in 12 bytes fixed length ASCII characters. The baud rate of output is 9600 bps.

Example output string on screen would be strings like below,

08.125 Kg.

12.546 Kg.

The first two ASCII digits shows kilogram and rest 3 digit after decimal point shows gram unit.

The string starts with 0x0A which is new line as well as start of string idenfier. The string ends with 0x0D which is acting as line feed character or End of string idenfier.

Count ->


































‘ ‘





Fixed Out->













Command Format

Commands are simple ASCII characters that are sent to board to control the functions of the board like auto zero, scaled output, raw output.

Commands in ASCII Details of command
'C' or 'c' Calibrate input to zero readings
'K' Output in Kg. scaled to 40 KG Load cell. Default at power up
'R' Output in RAW mode. Unscaled output direct from internal ADC.

Output Types - Scaled or RAW

When you start up the board, its ready for work with 40 KG load cell with its internal ADC output scaled to give you correct readings in Kg(Kilogram) for 40 KG load cell. That is the scaled output mode. The output of ADC is internally multiplied by factor of 0.38 constant before it is serially output. This is how we multiply reading internally for 40 KG Load cell. Keep reading to see how we got 0.38 for 40 KG load cell.

Scaling means increasing the output to a fixed percentage of input. What percentage to increase is your scaling factor.


If you wish to have different type of load cell like a 5 KG load cell. you will have to use unscaled output mode, called RAW mode. To get RAW output reading, you will have to send command character 'R' once to board after power up. In RAW mode the ADC readings are output directly as serial data without scaling. Now you can use this ADC readings and multiply externally in your microcontroller or PC software with a constant scaling factor to get correct output readings in KG. 

To switch back to scaled mode you can anytime send the board command 'K'.

Internally the output of 24 bit ADC is not scaled or matched with correct weight output. The output of ADC has to be multipled with a constant scaling factor to arrive at output readings which is direct in Kilograms. To arrive at correct scaling factor for your load cell, you will a need to get a known weight like 1 KG load. Then in excel enter the RAW ADC readings and adjust till you get 1KG output. A example if shown below how we arrived at 0.38 factor for 40 KG Load cell. You can download our Excel file from download area on this page.

Terminal software

We recommend Terminal software which can be used receive serial data for testing purpose on PC side.1190.gif

Connecting Load Cell

You will need a load cell to connect to board input (Load cell is not included with board). The four wires of load cell are to be connected to four input terminals as below.

EXT+ On board +5V is connected to this terminal to give excitation voltage to load cell.
Load cell will usually have RED color wire for this terminal.
EXT- On board Ground connected to this terminal to give ground and shield to load cell.
Load cell will usually have BLACK wire for this terminal.
SIG+ Signal output positive. Load cell will usually have GREEN wire for this terminal. 
SIG- Signal output negative. Load cell will usually have WHITE wire for this terminal.  

Auto Zero

Autozero and Calibration is performed automatically during start up. In case you need to force the system to do autozero and calibration, You can send ASCII character ‘c’ for the purpose anytime. It takes 5 second to perform the operation. Also note that at powerup the reading output string will appear after 5 seconds due to auto zero and calibration functions in process.

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