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Instruction Manual
Analog Output
7
The VGC301 provides either a non-linear, log-linear or a 0-10 Vdc linear analog output signal. These analog output
signals are also compatible with various Granville-Phillips® Mini-Convectron® modules as well as Convectron® gauge
controller series 375, 475 and the original 1/4 DN 275 Analog Convectron Gauge Controllers. Please read this section
in its entirety to determine which one of the five analog output types to select from.
The analog output information described in this User Manuals applies to VGC301 manufactured with the current
firmware XXXXX-11 and higher (last two digits of 11 or higher). See INFO screen of the VGC301 display menu to
determine the firmware version you are using. When compared to the previous versions of the VGC301
firmware, the current version of the firmware provides additional analog output scaling options as listed in the
table below.
Analog Output Types
Log-Linear 1 to 8 Vdc, 1 V/decade
Log-Linear 0 to 7 Vdc, 1 V/decade
Non-Linear 0.375 to 5.659 Vdc, S-Curve
Non-Linear 0 to 9 Vdc, S-Curve
Linear 0 to 10 Vdc
LOG 1-8; Log-Linear Analog Output
The LOG 1-8 setting selected from the ANALOG TYPE menu
produces a log-linear analog output signal of 1 to 8 Vdc for
1.0E-4 to 1000 Torr of N
. This output, shown at right, is a 1
2
Volt per decade signal that may be easier to use for data
logging/control than the non-linear analog output.
Selecting the LOG 1-8 setting from the InstruTech VGC301
ANALOG TYPE menu duplicates the analog outputs of the
Granville-Phillips Convectron® gauge controller series 375
and 475.
If you also have a previous version(s) of 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 "LOG 1-8 " menu selection in the
current firmware corresponds to the "LOG" menu selection
of the older firmware
The equations and tables shown in
section 7.2
contain the lookup data for converting the
LOG 1-8 output voltage into pressure values for nitrogen
and various other gases.
InstruTech, Inc.
Current VGC301 Firmware
XXXXX-11 (last 2 digits = 11 or Higher)
ANALOG TYPE Menu Selection
LOG 1-8
LOG 0-7
NONLIN 6V
NONLIN 9V
LINEAR
section 7.1
and
VGC301 Controller
Previous VGC301 firmware
XXXXX-10 (last 2 digits = 10 or lower)
ANALOG TYPE Menu Selection
=
LOG
=
Not Available
=
NONLIN
=
Not Available
=
LINEAR
Page 19
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