OMC-042 / 043 / 044 Data loggers
Users
’ manual
page 74
Analog Differential input 5
Analog input 5 is a Differential input with a build-in user selectable input-amplifier. Therefore channel 5
has a user selectable range. The user can set the range of the input according to his preferences. This is
done by adjusting the so called “port mode” The Ranges are given in the table underneath:
Input 5 ranges
Port mode
Voltage
0
0 .. 250mV
1
0 .. 500mV
3
0 .. 1000mV
4
0 .. 2000mV
Analog Differential input 6
Analog input 6 is the most sensitive differential input of the OMC-042. With exception of this sensitivity,
the channel is similar to channel 5.
Input 6 ranges
Port mode
Voltage
0
0 .. 10mV
1
0 .. 20mV
3
0 .. 40mV
4
0 .. 80mV
Calibration of Differential inputs
The Differential inputs are calibrated at the factory. This calibration is a so called 1 point zero offset
calibration. With this type of calibration, only the value at zero is adjusted. For input 5 this is very
accurate, it will be < 0.05 %. For an application that requires an even higher accuracy, the user can and
should do a user
– overall calibration.
Overall Calibration
This type of calibration is offered to the user to get the most accurate readings possible. This type of
calibration is a two point’s calibration.
How it works:
The user can enter 2 pre-defined data values into the OMC-042. This is very convenient for i.e. Scales.
For example, the user has a standard load of 1 kg and one of 10 kg. He starts the calibration procedure,
and starts with the 1.0 kg load. The data logger, now, adapts the 1 kg and stores this value. Again with
the 10.0 kg load, it adjusts the scale to 10.0 kg and stores the settings. Now, the logger will calculate a
linear function between the two points. Note that all deviations in the sensor or the load are compensated
from now on. With this type of calibration an accuracy of < 0.01 % is possible.
Note: for Channel six, with the enhanced pre-amplifier, this overall calibration is a must do. It is not
sufficient to only use the factory calibration. The factory calibration for this input is < 0.5%.