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5.1.6
Load Cell User Calibration Parameters
The SP-010 provides four User Calibration registers that allow setting a 2-point calibration / linearization of the
specific load cell. The four parameters may only be set while the device is in the
User Calibrate mode
. When the
calibration function is triggered the device will calculate the Gain and Offset used in the linearization process.
The calibration process is performed by the following steps:
Step 1:
Send Sensor Function
Calibrate Mode
trigger to set device to calibration mode.
Step 2:
Apply a known weight and record in the User Calibration register 1 (Actual Low).
Step 3:
Record the measured value in User Calibration register 0 (Reading Low).
Note:
A Sensor “Capture Low” trigger function allows automatically capturing the value.
Step 4:
Apply a 2
nd
known weight and record in the User Calibration register 3 (Actual High).
Step 5:
Record the measured value of the 2
nd
weight in User Calibration register 2 (Reading High).
Note:
A Sensor “Capture High” trigger function allows automatically capturing the value.
Step 6:
Send Sensor Function “Start Calibrate” trigger generate the Gain and Offset values.
The four calibration parameters represent two sets of reading, where X = actual applied load and Y represents the
reading captured by the device after the calibration process:
User
Calibration
Parameter
Name
Range
Factory
Reset
Description
0
Low Reading (X1)
+/- 100000
0.0
Value read by SP010 (lower value)
1
Low Actual (Y1)
+/- 100000
0.0
Actual applied load (lower value)
2
High Reading (X2)
+/- 100000
Full Scale
Value read by SP010 (higher value)
3
High Actual (Y2)
+/- 100000
Full Scale
Actual applied load (higher value)
Result = Reading *
Gain
+
Offset
,
Where:
Gain = (Y2 – Y1) / (X2 – X1)
Offset = (X1 * Gain) – Y1
Note:
The device must be put into the ‘Calibration’ mode to access the User Calibration parameters.
While in the
Calibration mode the raw Reading value will be displayed, and the TARE offset is ignored.
5.1.7
Load Cell IPSO Definition
The Load Cell sensor IPSO definition provides signal range, measured min/max values, IPSO object type information.
The Range information is Load Cell Type dependent. The SP-010 Load Cell IPSO definition is at base address 0x08a8.
Offset
Name
Value
Description
0x00
Sensor Type
3322
Load
0x02
Precision
??
Provides reading of xxx.x. Set to support 0.1% full scale
reading. For example, if full scale is 100, Precision is set
to 1 (xxx.x)
0x04
Sensor Trigger
??
Write 0x0001 to force reset of min / max
0x08
Min Measured
??
Minimum reading since last reset
0x0c
Max Measured
??
Maximum reading since last reset
0x10
Min Range
??
Set to 1.5 X Full scale reading
0x14
Max Range
??
Set to -1.5 X Full scale reading