Instruction Manual VGC301 Controller
InstruTech, Inc.
Page 21
NONLIN 9V; Non-Linear Analog Output, S-Curve
The NONLIN 9V setting selected from the ANALOG TYPE
menu produces a non-linear analog output signal of
0 to 9
Vdc for 0 to 1000 Torr of N
2
, roughly in the shape of an "S"
curve, as shown at right.
Selecting the NONLIN 9V setting from the InstruTech
VGC301
ANALOG TYPE
menu duplicates the analog outputs
(S-Curve) of the Granville-Phillips Convectron® gauge
controller series 375, 475 and the original 1/4 DN 275
Analog Convectron Gauge Controllers.
The NONLIN 9V option was not previously available for the
VGC301 product manufactured with firmware XXXXX-10
or
lower (last 2 digits of 10 or lower, see firmware number in
the
INFO
screen of the display menu).
The equations and table shown in
section 7.8
contain the
lookup data for converting the
NONLIN 9V
output voltage
into pressure values for nitrogen and various other gases.
LINEAR; 0-10 Vdc Linear Analog Output
The VGC301 also provides a linear 0-10 Vdc analog output. The linear output voltage can be any value between 0.01
V and 10 V corresponding to displayed pressure between 1 mTorr and 1000 Torr. However, the useful range of the linear
analog output is three decades. For example if the minimum pressure selected is 1 mTorr (1.0 x 10
-3
Torr) with a
corresponding minimum voltage output of 0.01 volts, then maximum pressure selected to correspond to a maximum
voltage output of 10 volts should not exceed 1.00 Torr. If your application requires the analog output to cover a pressure
range exceeding three decades then consider using the log-linear or non-linear analog output. See
section 7.9
for more
detailed explanation.
