CiDRA SONARtrac PW VF-100 - Manual (Page 166)

20834-01 Rev 04 Page 8-22
8.4 Input Config Menu
The Input Config menu is used when optional external sensors (for
example a pressure or temperature sensor) are powered by and input
to the transmitter. The transmitter has the ability to display, store and
transmit these values using serial communications, but not output
them using the 4-20mA outputs. Note: When these sensor inputs are
used the ’Temperature Sel’ and ‘Pressure Sel’ menu options under
the ‘Basic Config’ menu must be used to designate which sensor
input is used for a particular measurement.
These inputs are not normally used with VF and TAM systems.
8.4.1 Sensor 1 & 2
Sensor 1 & 2 are typically user supplied loop powered 4-20mA
pressure or temperature transmitters which the passive sonar meter
transmitter supplies with a nominal +24V. The pressure or
temperature transmitter electrical connections must be isolated from
ground ("floating").
8.4.1.1 Units
Units allows for setting the sensor units to ‘None’ (not used) ‘F’
(temperature degrees
F), ‘C’ (temperature degrees C), ‘Barg’
(pressure in Bars gauge), ‘kPag’ (pressure in kilo Pascals gauge),
‘PSIg’ (pressure in pounds per square inch gauge).
8.4.1.2 Scale
Scale sets the range of input in units of measure (‘Units’) per mA. For
example a pressure transducer has a range of 0-100 psi and an
output of 4-20 mA. For this transducer the scale will be:
scale = range / (mA High output – mA Low output)
scale = 100 psi / 16mA
scale = 6.25 psi/mA
8.4.1.3 Offset
Offset allows for setting an offset in mA due to a non-zero milliamp
sensor output range. The offset is calculated by the equation y=mx+b
where: y is a value within the transducer range, m is the transducer
scale, x is the milliamp output at the ‘y’ value, and b is the offset.
For example, a 0-100 psig pressure transducer with a 4-20 mA output
will have a
–25 psi offset.
y=mx+b
100 psi = (100psi / 16mA) x (20mA) +b
100 psi – 125 psi = b
- 25 psi = b = ‘Offset’