63
FC-21 Flow Computer
Mass Flow is inferred by the volumetric flow and density (or implied density) of a fluid.
Maximum Batch Preset
The Maximum Batch Preset allows the user to program the Maximum Batch value allowed to be entered
by the operator. If an operator should try to program a batch higher then this value, the unit will not allow
the value to be entered and will prompt the user with an error message saying that the Maximum Batch
Preset has been exceeded.
Maximum Drain Time
The unit declares that a batch is “done” when the flow rate equals “0”. A flow rate may be present long
after the Preset Relay de-energizes due to slow reacting valves or leaky valves. The Maximum Drain
Time allows the user to enter an amount of time (0 to 99 seconds) to wait before declaring “Batch Done”.
After the Preset Batch quantity is reached, the unit will declare “Batch Done” when the flow rate is “0” or
the Maximum Drain Time has expired. The batch data will then be available for printing and datalogging.
Max Window
The max. window time sets the maximum sample time (1 to 99 sec) for the ratemeter.
Modem Init Master
The "Modem Init Master" menu allows the user to select whether the unit will engage in a configuration
conversation with the modem on power up or impart no setup information to the modem and use it "as
is". For most users it is recommended to choose "yes" for "Modem Init Master".
Orifice Plate Flowmeter
A class of flow measurement devices where the measured signal (differential pressure) has a square law
relationship to flow.
Parity
A method for detecting errors in transmissions of serial communications data.
Preset
A set point used to trigger the relay outputs of the FC-21.
Print Interval
The print interval allows the FC-21 to transmit information to the serial port at selectable time intervals.
Private Code
An operator password code which authorizes changes to the setup of the instrument but blocks access to
the Service/Calibration/Test mode. The private code also blocks the clearing of the Grand Total.
Process Parameters
Any sensor information which has been scaled to engineering units including Flow, Temperature and
Density.
Pulldown
(Input Termination)
The termination of an input at which the input is pulled down to ground through a resistor. Inputs that
are terminated by this method need to be driven high with a positive voltage pulse.
Pullup
(Input Termination)
The termination of an input at which the input is pulled up to a positive voltage through a resistor.
Inputs that are terminated by this method need to be pulled low with a sinking current or contact to
ground .
Pulse Output
The pulse output of the FC-21 is available for remote accumulation of the total or sent to peripheral
devices, such as a PLC. The output can be scaled using the Pulse Output Scaling Constant.
Quad
Abbreviation for Quadrature. Quadrature signals are used for direction control. Two flowmeter signals
are output with a 90
°
phase shift. The counter counts UP when channel A precedes channel B, and
counts DOWN when Channel A lags Channel B.
Quick Setup
A utility that provides for rapid configuration of an instrument. The FC-21 quick setup provides the
12. Glossary Of Terms
(Continued)
