Alicat VC Series Volumetric Flow Controller - Manual (Page 8)

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the connections, i.e. the connector on top of the meter and the physical DB-9 serial port on the back of
the computer. The cable ends will be mirror images of the diagram shown in Figure 3. (See page 21 for
details on accessing RS-232 output.)
Standard Voltage (0-5 Vdc) Output Signal
All MC and VC series flow controllers have a 0-5 Vdc (optional 0-10 Vdc) output signal available on Pin
6. This is generally available in addition to other optionally ordered outputs. This voltage is usually in
the range of 0.010 Vdc for zero flow and 5.0 Vdc for full-scale flow. The output voltage is linear over the
entire range. Ground for this signal is common on Pin 8.
Optional 0-10 Vdc Output Signal
If your controller was ordered with a 0-10 Vdc output signal, it will be available on Pin 6. (See the
Calibration Data Sheet that shipped with your controller to determine which output signals were
ordered.) This voltage is usually in the range of 0.010 Vdc for zero flow and 10.0 Vdc for full-scale flow.
The output voltage is linear over the entire range. Ground for this signal is common on Pin 8.
Optional Current (4-20 mA) Output Signal
If your controller was ordered with a 4-20 mA current output signal, it will be available on Pin 1. (See
the Calibration Data Sheet that shipped with your controller to determine which output signals were
ordered.) The current signal is 4 mA at 0 flow and 20 mA at the controller’s full scale flow. The output
current is linear over the entire range. Ground for this signal is common on Pin 8. (Current output units
require 15-30Vdc power.)
Note: This is a current sourcing device. Do not attempt to connect it to “loop powered” systems.
Optional 2nd Analog Output Signal
You may specify an optional 2nd analog output on Pin 2 at time of order. (See the Calibration Data Sheet
that shipped with your controller to determine which output signals were ordered.) This output may be
a 0-5 Vdc, 0-10 Vdc, or 4-20 mA analog signal that can represent any measured parameter. With this
optional output, a volumetric flow controller could output the volumetric flow rate with a 0-5 Vdc signal
(on pin 6) and a 4-20 mA signal (on pin 2), or a mass flow controller could output the mass flow rate
(0-5 Vdc on pin 6) and the absolute pressure (0-5 Vdc on pin 2).
Note: This is a current sourcing device. Do not attempt to connect it to “loop powered” systems.
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4
6
2 1
DB-9 Serial Port
5
5----------Ground--------------------------------------Ground----------8
3----------Transmit------------------------------------Receive---------3
2----------Receive-------------------------------------Transmit--------5
8 Pin Mini-DIN Port
8
1 2 3 4 5
6 7 8 9
3
4 5
6 7 8
2
Figure 3. Mini-DIN to DB-9 Connection for RS-232 Signals