Thyracont VSI17D, Operating Instructions Manual

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VSI-de-170326
Control signal - Cathode Control Logic (DL)
The cold cathode sensor can be switched on and off by applying a defined volt-
age signal to pin 9 of the transducer's electrical connector (see chapter 3.3.2).
By means of device parameter Cathode Control Logic (DL) you can select via
software command, if a 24 VDC or GND level signal shall be used:
"0":
GND
"1": 3…24 VDC (default)
The cold cathode sensor will be active as long as the voltage signal is applied.
Parameter Cathode Control Logic (DL) can also be queried.
When the cold cathode sensor is off the VSI will not transmit pressure measure-
ments, 9.8 V are applied to the analog signal output.
Gas Correction Factor (C4)
The output signal of the VSI depends on type and composition of the gas being
measured. The unit is adjusted for N
2
and dry air. For other gases the pressure
display can be corrected by setting the related correction factor C4 for the cold
cathode sensor via RS485.
The measurement results of the sensor are then multiplied with this factor by the
units microcontroller. The VSI can thereby provide a corrected pressure signal as
analog and digital output.
Correction factor cold cathode:
Ar
0,80 H
2
2,4 N
2
1,0 Kr 0,6
CO
2
0,74 He 5,9 Ne 3,5 Xe 0,41
Output Scaling - Analog Output Characteristic (OC)
The analog output characteristic of the VSI can be scaled according to applica-
tion requirements by adjusting this parameter via software command.
The voltage output curve can, for example, be made directly compatible with
transducers of other brand labels.