COSA Xentaur Hygrocontrol Type 83 - Manual (Page 8)

HYGROCONTROL Manual for Type 83 Page - 7 -
To do a calibration, the transmitter has to be connected to a computer
with a coupler type LPT (changes RS232/3V with galvanic isolation to
USB). The computer should have a driver which installs a virtual
COM-Port. Possible and necessary commands are shown in next
chapter.
We recommend doing a calibration at 2 humidity points which are
widely separated (for example 0%RH and 80%RH). With a calibration
of these 2 points you will get a straight line characteristic which fits to
the sensor characteristic better than +-2%RH between 0%RH and
80%RH and better than +-3%RH between 80%RH and 100%RH.
To achieve more accuracy for your instrument, now point calibrations
at other fixed points may be done at values of 10, 20, 35, 50, 65 and
95 %RH which brings the characteristic line closer to the individual
sensor characteristic and will result in accuracies of 0.5 %RH at the
calibrated points. These calibrations are always done at our factory
before the instruments are shipped to our customers.
If changes of more than 5%RH will occur at any point of the scale you
are calibrating, you should finish the calibration and delete all values
in the calibration memory and start with a new calibration as
mentioned before. Only after this step new point calibrations may
make sense. Never disconnect the power supply during a calibration.
We divided the scale of 0%RH to 100%RH into 10 segments
which are 0...4%, 4,1...15%, 15,1...26%, 26,1...37%, 37,1...48%,
48,1...59%, 59,1...70%, 70,1...82%, 82,1...92% and 92,1...100%RH.
Each new calibration in one of these segments will replace the
old value in the segment by the new one.
If a new straight line characteristic is wanted, first the old values in the
memory must be deleted by function %E. After this is done, the
memory has only 2 values – this are the first so-called “initial” points
calibrated at the factory at 0%RH and 80%RH. Now you should
recalibrate 2 points in the segments 0...4% and 70,1...82%RH. Only
by this procedure you will have done a new straight line characteristic.
5.2.5. Operation via BUS commands
To do a calibration, the transmitter has to be connected to a computer
with a coupler type LPT (changes RS232/3V with galvanic isolation to
USB). The computer should have a driver which installs a virtual
COM-Port. Operation is possible with a terminal program. The virtual
COM-Port must be adjusted to 9600-8N1. Possible and necessary
commands are: