Calibration And Adjustment - Beckhoff EP3356-0022 Documentation

Commissioning/Configuration
6.7

Calibration and adjustment

The term "calibration" can be applied in 3 different ways to the EL/EP3356:
• Sensor calibration: once-only calibration of the employed sensor (strain gauge) during commissioning
of the system
• Self-calibration: continuously repeated self-calibration of the terminal/box for the improvement of the
measuring accuracy
• Tare: repeated gross/net compensation by taring
EL/EP3356 and special versions
Unless stated otherwise, the designation „EL/EP3356" always refers also to special versions such
as the EL3356-0010 and the EP3356-0022.
Sensor calibration
The EL/EP3356 is matched to the characteristic curve of the sensor element by means of the calibration.
Two values are required for this procedure: the initial value without a load ("zero balance") and fully loaded
("rated output"). These values can be determined by a calibration protocol or by a calibration using
calibration weights.
Fig. 76: Adaptation to the sensor curve
Calibration by means of compensation in the system
In the "practical" calibration, measurement takes place first with the scales unloaded, then with a defined
load on the scales. The EL/EP3356 automatically calculates the existing sensor characteristic values from
the measured values.
Sequence:
1. Perform a CoE reset with object 0x1011:01, see Restoring the delivery state [} 118]
2. Set scale factor to 1000 (0x8000:27 [} 104]) (for declaration of weight in g)
3. Set gravity of earth (0x8000:26 [} 104]) if necessary (default: 9.806650)
4. Set gain to (0x8000:21 [} 104]) = 1
5. Set tare to 0 (0x8000:22 [} 104])
6. Set the filter (0x8000:11 [} 104]) to the strongest level: IIR8
7. Specify the nominal load of the sensor in 0x8000:24 [} 104] ("Nominal load")
80 Version: 1.1.0 EP3356-0022