Instruction Manual VGC301 Controller
InstruTech, Inc.
Page 35
7.9
LINEAR
The
VGC301
analog output may be setup to provide a 0-10 Vdc output signal that has a direct linear relationship
to the displayed pressure. When preparing to setup and process the linear analog output signal, first define the
following parameters that you will program into the
VGC301:
Minimum measured pressure (for the defined analog output range )
Minimum output voltage desired (proportional to the minimum pressure)
Maximum measured pressure (for the analog output signal range)
Maximum output voltage desired (proportional to maximum pressure)
Constructing a table of these parameters may be useful in documenting the relationship of displayed pressure to
the analog output voltage. For example, the following table is representative of a typical setup where;
Min P = 1.00E-03 Torr Min Voltage = 0.01 Volts
Max P = 1.00 Torr Max Voltage = 10 V
Linear Analog Output Voltage - volts
Measured (Displayed) Pressure - torr
0.01
1.00E -03
0.10
1.00E -02
1.00
1.00E -01
10.00
1.00E +00
It is recommended that the
Linear
output signal be setup such that the range covers, at most, 3 decades of
pressure change. For example, if the minimum pressure selected is 1 mtorr (1.0E -03 torr) with a corresponding
minimum voltage output of 0.01 volts, then the maximum pressure selected to correspond to a maximum
voltage of 10.0 volts should not exceed 1.0 torr.
Doing this is considered best practice when using this type of analog output signal with the
VGC301.
If your application requires the analog output voltage to cover a pressure range exceeding three decades, then
consider using the log-linear or non-linear analog output.
Note - When using the LINEAR (0-10 Vdc) analog output, an output of 11 volts indicates a faulty convection gauge or
unplugged gauge cable.
