Support Forums
Load cell channel definition

Hello,

I have 2 load cells, 0-5000 lbs on channel 3 and 0-1500 lbs on channel 4. I have interfaced each channel with BGI. I would like to know the syntax to label channel 3 as ''Balance'' and channel 4 as ''Moule à rebond''. Also, I have PPM but what is the syntax to convert to span to pounds.

Thank you,

Richard

Hello, I have 2 load cells, 0-5000 lbs on channel 3 and 0-1500 lbs on channel 4. I have interfaced each channel with BGI. I would like to know the syntax to label channel 3 as ''Balance'' and channel 4 as ''Moule à rebond''. Also, I have PPM but what is the syntax to convert to span to pounds. Thank you, Richard

Hi Richard,

You may use the following method:
'assuming those sensor have the following rating:
'sensor 3: rated output of 2.000 mV/V @ 5000 lbs which mean 2000 ppm for 5000 lbs (you need to check sensor calibration document).
'sensor 4: rated output of 2.100 mV/V @ 5000 lbs which mean 2100 ppm for 1500 lbs (you need to check sensor calibration document).

'scaling entry to convert ppm to lbs
'writing style Sn=targetlow,targethigh,readlow,readhigh
S1=0,5000,0,2000"lbs"
S2=0,1500,0,2100"lbs"

'Offset reading (it will run at the start of program to set an offset value, remember to remove any load from load cell during this phase)
3BGI("Offset Balance~ppm",=11CV,W)
4BGI("Offset Moule a rebond~ppm",=21CV,W)

RA1M
'Raw reading, this is the reading without an offset (because you do not need these figures, they must be set as working channels).
3BGI("Raw Balance~ppm",=12CV,W)
4BGI("Raw Moule a rebond~ppm",=22CV,W)

'Actual readings are obtained by negate raw reading with the offset and apply the scaling
13CV("Balance~lbs",S1)=12CV-11CV
23CV("Moule a rebond~lbs",S2)=22CV-21CV

If you are using dEX, you have to put two current bridge channel for the offset reading under "On Logger Activation"

Best regards,
Rudy Gunawan

Hi Richard, You may use the following method: 'assuming those sensor have the following rating: 'sensor 3: rated output of 2.000 mV/V @ 5000 lbs which mean 2000 ppm for 5000 lbs (you need to check sensor calibration document). 'sensor 4: rated output of 2.100 mV/V @ 5000 lbs which mean 2100 ppm for 1500 lbs (you need to check sensor calibration document). 'scaling entry to convert ppm to lbs 'writing style Sn=targetlow,targethigh,readlow,readhigh S1=0,5000,0,2000"lbs" S2=0,1500,0,2100"lbs" 'Offset reading (it will run at the start of program to set an offset value, remember to remove any load from load cell during this phase) 3BGI("Offset Balance~ppm",=11CV,W) 4BGI("Offset Moule a rebond~ppm",=21CV,W) RA1M 'Raw reading, this is the reading without an offset (because you do not need these figures, they must be set as working channels). 3BGI("Raw Balance~ppm",=12CV,W) 4BGI("Raw Moule a rebond~ppm",=22CV,W) 'Actual readings are obtained by negate raw reading with the offset and apply the scaling 13CV("Balance~lbs",S1)=12CV-11CV 23CV("Moule a rebond~lbs",S2)=22CV-21CV If you are using dEX, you have to put two current bridge channel for the offset reading under "On Logger Activation" Best regards, Rudy Gunawan

Thank you very much Rudy for your info.

The 'Moule a Rebond' seems to be working well so far, but for some reason it works well with voltage excitation and not current. The 'Balance' had some drifting issues with its PPM. I think I figured out it is a 1000 Ohms bridge so I made the change in the command. I also specified it is a 4-wire bridge. Now I have a window of about 2 to 3 PPM where the 'Balance' keeps itself in.

The only problem I have is that for 180 lbs the signal only varies about 15 PPM so that my zero fluctuates about +/- 20 pounds which is unacceptable. Is there a way to add a factor so that my PPM would be bigger and so I could have a greater resolution and therefore even though the PPM would vary a little, it would not matter that much ?

Thank you

Richard

BEGIN "Projete"

/h/E/R/s/w/Z

P28=2
P31=2
P39=0
P50=1
P51=1

S5=0,1500,0,2450"Lbs"
S6=0,5000,0,200"Lbs"
3BGI(4W,1000,=11CV,W)
4BGV("Offset Moule a Rebond~ppm",=21CV,W)

RB5S

3BGI(4W,1000,"Raw Balance~ppm",=12CV,W)
13CV("Balance:~lbs",S6)=12CV-11CV
4BGV("Raw Moule a Rebond:~ppm",=22CV,W)
23CV("Moule a Rebond~lbs",S5)=22CV-21CV

LOGOFF
END

Thank you very much Rudy for your info. The 'Moule a Rebond' seems to be working well so far, but for some reason it works well with voltage excitation and not current. The 'Balance' had some drifting issues with its PPM. I think I figured out it is a 1000 Ohms bridge so I made the change in the command. I also specified it is a 4-wire bridge. Now I have a window of about 2 to 3 PPM where the 'Balance' keeps itself in. The only problem I have is that for 180 lbs the signal only varies about 15 PPM so that my zero fluctuates about +/- 20 pounds which is unacceptable. Is there a way to add a factor so that my PPM would be bigger and so I could have a greater resolution and therefore even though the PPM would vary a little, it would not matter that much ? Thank you Richard BEGIN "Projete" /h/E/R/s/w/Z P28=2 P31=2 P39=0 P50=1 P51=1 S5=0,1500,0,2450"Lbs" S6=0,5000,0,200"Lbs" 3BGI(4W,1000,=11CV,W) 4BGV("Offset Moule a Rebond~ppm",=21CV,W) RB5S 3BGI(4W,1000,"Raw Balance~ppm",=12CV,W) 13CV("Balance:~lbs",S6)=12CV-11CV 4BGV("Raw Moule a Rebond:~ppm",=22CV,W) 23CV("Moule a Rebond~lbs",S5)=22CV-21CV LOGOFF END

Hi Richard,

For more accurate reading, you should use voltage bridge for 'Balance' as well. It will give you less fluctuation.
About factoring the ppm reading, you may use this method (please check polynomial Y7 and S6 changes):

S5=0,1500,0,2450"Lbs"
S6=0,5000,0,20000"Lbs"
Y7=0,100
3BGI(4W,1000,Y7,=11CV,W)
4BGV("Offset Moule a Rebond~ppm",=21CV,W)

RB5S

3BGI(4W,1000,"Raw Balance~ppm",=12CV,Y7,W)
13CV("Balance:~lbs",S6)=12CV-11CV
4BGV("Raw Moule a Rebond:~ppm",=22CV,W)
23CV("Moule a Rebond~lbs",S5)=22CV-21CV

Best regards,
Rudy Gunawan

Hi Richard, For more accurate reading, you should use voltage bridge for 'Balance' as well. It will give you less fluctuation. About factoring the ppm reading, you may use this method (please check polynomial Y7 and S6 changes): S5=0,1500,0,2450"Lbs" S6=0,5000,0,20000"Lbs" Y7=0,100 3BGI(4W,1000,Y7,=11CV,W) 4BGV("Offset Moule a Rebond~ppm",=21CV,W) RB5S 3BGI(4W,1000,"Raw Balance~ppm",=12CV,Y7,W) 13CV("Balance:~lbs",S6)=12CV-11CV 4BGV("Raw Moule a Rebond:~ppm",=22CV,W) 23CV("Moule a Rebond~lbs",S5)=22CV-21CV Best regards, Rudy Gunawan

Thank you Rudy,

I think I have pinpointed the issue. I sample at 2Hz and the 'Balance' load cell seem to slowly drift from its zero value to about 5kg on the positive side when no load is applied. At some point, maybe 5 minutes after the initial sampling, the DT80 does 3 very fast samples and that seems to reinitialize, or grounds' something in the DT80, because the value goes back to around 0kg. Is there something I am not getting or is there a parameter I need to set? I checked the P21 and set it to 1 from 0 but it has not changed anything.

Thank you,

Richard

Thank you Rudy, I think I have pinpointed the issue. I sample at 2Hz and the 'Balance' load cell seem to slowly drift from its zero value to about 5kg on the positive side when no load is applied. At some point, maybe 5 minutes after the initial sampling, the DT80 does 3 very fast samples and that seems to reinitialize, or grounds' something in the DT80, because the value goes back to around 0kg. Is there something I am not getting or is there a parameter I need to set? I checked the P21 and set it to 1 from 0 but it has not changed anything. Thank you, Richard

Hi Richard,

Wheatstone bridge is very sensitive, it could be the reaction of bridge components on applied excitation voltage.
It may need some time to stabilize the reading.

Although I believe every components or sensors have different response, I can't say for sure why bridge balance happens after 5 minutes.

Best regards,
Rudy Gunawan

Hi Richard, Wheatstone bridge is very sensitive, it could be the reaction of bridge components on applied excitation voltage. It may need some time to stabilize the reading. Although I believe every components or sensors have different response, I can't say for sure why bridge balance happens after 5 minutes. Best regards, Rudy Gunawan

Good morning Richard,

It will be the house keeping. If the zero drifts by more than three microvolts the house keeping rezeros the electronics.
This results in the resetting you are seeing. The total error will be less than 0.1% of reading.

Cheers

Roger

Good morning Richard, It will be the house keeping. If the zero drifts by more than three microvolts the house keeping rezeros the electronics. This results in the resetting you are seeing. The total error will be less than 0.1% of reading. Cheers Roger
38
6
3
live preview
enter atleast 10 characters
WARNING: You mentioned %MENTIONS%, but they cannot see this message and will not be notified
Saving...
Saved
With selected deselect posts show selected posts
All posts under this topic will be deleted ?
Pending draft ... Click to resume editing
Discard draft