Decode Load Cell Data that Received by Serial Port

[fences]

I read some data from serial port(RS232). this data about LoadCell Information. in other hand i have loadcell that connect to PC by Serial port. I test this load cell with 3 deferent weight; 0kg , 3.5kg and 5.5kg. this load cell send data in every 20ms to PC. ( there is a send loop on loadcell).

for 0.0 kg ( with 0.1 telorance -> 0.0-0.1kg) i have :
2A 78 B6 2A 78 AE 2A 78 88 2A 78 6F 2A 78 6E 2A 78 99 2A 78 B9 2A 78 AF 2A 78 88 2A 78 71 2A 78 6F 2A 78 9C 2A 78 B9 2A 78 AE 2A 78 89 2A 78 71 2A 78 6E 2A 78 99 2A 78 B7 2A 78 AF 2A 78 89 2A 78 70 2A 78 6F 2A 78 9A 2A 78 B7 2A 78 AC 2A 78 88 2A 78 71 2A 78 6F 2A 78 9A 2A 78 B7 2A 78 AE 2A 78 89 2A 78 70 2A 78 6F 2A 78 9B 2A 78 B7 2A 78 AD 2A 78 88 2A 78 70

for 3.5 kg ( with 0.1 telorance -> 3.5-3.6kg) i have :
2A 78 37 2A 78 30 2A 78 0D 0A 2A 77 F3 2A 77 EE 2A 78 2E 2A 78 37 2A 78 33 2A 78 2E 2A 77 F4 2A 77 F0 2A 78 2E 2A 78 38 2A 78 32 2A 78 2E 2A 77 F4 2A 77 EF 2A 78 2E 2A 78 37 2A 78 31 2A 78 2E 2A 77 F5 2A 77 EC 2A 78 2E 2A 78 38 2A 78 33 2A 78 2E 2A 77 F3 2A 77 EE 2A 78

and for 5.5kg ( with 0.1 telorance -> 5.5-5.6kg) i have :
2A 77 BA 2A 77 EA 2A 77 F9 2A 77 E2 2A 77 BC 2A 77 AD 2A 77 BD 2A 77 ED 2A 77 FA 2A 77 E2 2A 77 BD 2A 77 AD 2A 77 BB 2A 77 EB 2A 77 F8 2A 77 E0 2A 77 BC 2A 77 AD 2A 77 BE 2A 77 EC 2A 77 F9 2A 77 E1 2A 77 BC 2A 77 AC 2A 77 BC 2A 77 EB 2A 77 F9 2A 77 E0 2A 77 BC 2A 77 AE

these data had achived in about 2 second.

weight data send to PC each 20ms like this :

2A 78 B6 Read at 13:10:20:100

2A 78 AE Read at 13:10:20:125

2A 78 88 Read at 13:10:20:145

2A 78 6F Read at 13:10:20:165

2A 78 6E Read at 13:10:20:185 . . .

Now i want to know how can i convert this data to real weight?

like 2A 78 B6 to 0.1kg

is there any idea?

 

[barry]

Here's and idea: read the datasheet for the load cell.

There is no way to know WHAT your load cell is, what it's range is, what is data format is, who made it, etc..

 

[FvM]

I basically agree with "Read the datasheet", but in the meantime you can interprete the data as 24 bit hex numbers, convert to dezimal, average and determine a linear relation. Just some simple descriptive statistics.

According to the small variation and the standard deviation (0.8 - 1.5 kg) seen in the data points, I would expect that the load cell has at least several tons weight range.

There are periodical interferences (hum or mechanical vibrations) and some outliers. You surely need to average a larger number of data points to get 0.1 kg accuracy.

 

[fences]

yes you are right,this loadcell is U4000 Universal load cell fro . i read this datasheet : **broken link removed**
but I'm new in load cell interface. i try to convert these data to interger. results is:
0.0Kg = 2783385.0
5.5Kg = 2783166.0
how can i calculate this number? 2783231.0

thanks.

 

[FvM]

The datasheet doesn't describe a digital interface. Is it a commercial product or some selfmade electronics with unclear specification?

how can i calculate this number?

Something like below

 

[fences]

thank you , yes your are right. it is self-made electronics with unclear specification.
i get some more data that you can get it from blow link.
http://quartz.persiangig.com/5.5.txt
I use from HexEditor to analysis this data. ( number of received bytes in every 20ms is 3 ).


I am so confused! this data belongs to 5.5 kg. ( 5.3kg - 5.4kg - 5.6kg have same values ).
i have no idea to convert 24bits ( 3 bytes ) to 5 kg.
is there any other idea?
thanks.

 

[FvM]

Please see the below Excel File which shows how I got the transfer characteristic.

As said, the signal is affected by strong interferences, you must probably average 100 or more samples to get 0.1 kg uncertainty. For an accurate measurement, you would fix/improve the load cell electronics in a first step.

- - - Updated - - -

I looked another time at the data and found that the outliers at 2A7700 pretty well match the other data when they are arbitrarily changed to 2A7800. Also the linear trend line perfectly fits the three averaged points. This suggests a software bug in data processing of the interface (or less likely a transmission error). Waveform of the corrected data below.

 

[fences]

Thanks a lot.
it was helpful for me.

 

[mvagelis]

I read some data from serial port(RS232). this data about LoadCell Information. in other hand i have loadcell that connect to PC by Serial port. I test this load cell with 3 deferent weight; 0kg , 3.5kg and 5.5kg. this load cell send data in every 20ms to PC. ( there is a send loop on loadcell).

for 0.0 kg ( with 0.1 telorance -> 0.0-0.1kg) i have :
2A 78 B6 2A 78 AE 2A 78 88 2A 78 6F 2A 78 6E 2A 78 99 2A 78 B9 2A 78 AF 2A 78 88 2A 78 71 2A 78 6F 2A 78 9C 2A 78 B9 2A 78 AE 2A 78 89 2A 78 71 2A 78 6E 2A 78 99 2A 78 B7 2A 78 AF 2A 78 89 2A 78 70 2A 78 6F 2A 78 9A 2A 78 B7 2A 78 AC 2A 78 88 2A 78 71 2A 78 6F 2A 78 9A 2A 78 B7 2A 78 AE 2A 78 89 2A 78 70 2A 78 6F 2A 78 9B 2A 78 B7 2A 78 AD 2A 78 88 2A 78 70

for 3.5 kg ( with 0.1 telorance -> 3.5-3.6kg) i have :
2A 78 37 2A 78 30 2A 78 0D 0A 2A 77 F3 2A 77 EE 2A 78 2E 2A 78 37 2A 78 33 2A 78 2E 2A 77 F4 2A 77 F0 2A 78 2E 2A 78 38 2A 78 32 2A 78 2E 2A 77 F4 2A 77 EF 2A 78 2E 2A 78 37 2A 78 31 2A 78 2E 2A 77 F5 2A 77 EC 2A 78 2E 2A 78 38 2A 78 33 2A 78 2E 2A 77 F3 2A 77 EE 2A 78

and for 5.5kg ( with 0.1 telorance -> 5.5-5.6kg) i have :
2A 77 BA 2A 77 EA 2A 77 F9 2A 77 E2 2A 77 BC 2A 77 AD 2A 77 BD 2A 77 ED 2A 77 FA 2A 77 E2 2A 77 BD 2A 77 AD 2A 77 BB 2A 77 EB 2A 77 F8 2A 77 E0 2A 77 BC 2A 77 AD 2A 77 BE 2A 77 EC 2A 77 F9 2A 77 E1 2A 77 BC 2A 77 AC 2A 77 BC 2A 77 EB 2A 77 F9 2A 77 E0 2A 77 BC 2A 77 AE

these data had achived in about 2 second.

weight data send to PC each 20ms like this :

2A 78 B6 Read at 13:10:20:100

2A 78 AE Read at 13:10:20:125

2A 78 88 Read at 13:10:20:145

2A 78 6F Read at 13:10:20:165

2A 78 6E Read at 13:10:20:185 . . .

Now i want to know how can i convert this data to real weight?

like 2A 78 B6 to 0.1kg

is there any idea?

Hi,

How to connect load cell to rs232 ????

Vagelis