16
Analog Signals
Primary Analog Output Signal
Most Alicat instruments include a primary analog output signal, which is
linear over its entire range. For both standard 0-5 Vdc and optional 0-10 Vdc
output signals, a zero ow condition is usually in the range of 0.010 Vdc. Zero
ow for the optional 1-5 Vdc and 4-20 mA output signals is 1 Vdc and 4 mA,
respectively. Full-scale ow is 5 Vdc for 0-5 Vdc and 1-5 Vdc signals, 10 Vdc for
0-10 Vdc signals and 20 mA for 4-20 mA signals.
Alicat's default 8-pin mini-DIN connector places the primary analog output
on Pin 6 for voltage signals and Pin 1 for 4-20 mA current signals. Ground for
these signals is common on Pin 8.
Option: Second Analog Output Signal
Alicat's default 8-pin mini-DIN connector places the secondary analog output
on Pin 2 for both voltage and current signals. Your device's secondary analog
signal may dier from its primary output signal.
See the Calibration Sheet that shipped with your meter to determine
which output signals were ordered.
Option: 4-20 mA Current Output Signal
If your meter has a 4-20 mA current primary or secondary output signal, your
ow meter will require 15-30 Vdc power.
Caution: Do not connect 4-20 mA devices to “loop powered’” systems,
as this will destroy portions of the circuitry and void the warranty. If
you must interface with existing loop powered systems, always use a
signal isolator and a separate power supply.
Setpoint Analog Input Signal
Your mass ow controller may be a congured with a dierent analog inout
signal than its output signal(s). One method for providing a remote setpoint
to controllers with a 0-5 Vdc or 0-10 Vdc analog signal is shown below.
Note: Devices with 4-20 mA input signalsare current sinking devices.
The receiving circuit is essentially a 250 ohm resistor to ground.
Getting Started
5.12 Vdc
50 KOhm
Potentiometer
0-5 Vdc
1
2
3
4
5
6
7
8
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