MKS Mass-Flo 1479A, Instruction Manual, Page: 39 / 72

Chapter Four: Operation The Optional Input
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The Optional Input
The 1479/2479 MFCs can control flow based on a 0 to 5 Volt signal from an external sensing
device using the optional input feature. A common application of this feature is for pressure
control using input from a pressure transducer.
To use the optional input feature, route the output from the desired external device to the
appropriate “optional input” position for the connector; either a 15-pin Type “D” or an Edge Card
Connector. For the connector pinouts, refer to Table 4, page 20, and Table 5, page 21,
respectively.
Note
The 9-pin Type “D” connector does not support the optional input
feature. This feature is only available on the 15-pin Type “D” and Edge
Card connectors.
Voltage applied to the optional input pin overrides the signal generated by the flow sensor
internal to the 1479 unit. The control electronics drives the valve so that the optional input signal
matches the set point. Use the same pin for the set point signal, regardless of whether you are
using the optional input or the standard flow control signal.
Metered flow output is still available on the standard output pin.