Uf251_01d_oi_e.doc / Aug-16
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2.
Introduction
UF 251 represents a small and low-cost, but highly performing converter for industrial
applications, where analog signals need to be converted into a frequency or a serial data
format. The unit has been designed as a compact module with 12 screw terminals and two 9-
position SUB-D connectors (female and male). The housing is suitable for standard DIN rail
mounting.
A voltage input signal of ±10 V can be directly applied to screw terminals 1 and 4 (AGND). The
input resistance is approximately 100 kOhm.
It is also possible to use a potentiometer to set input voltage by connecting the centre tap of
the potentiometer to screw terminal 3 and the end taps to screw terminals 2 and 4. The
resistance of the potentiometer should be about 1 kOhm.
For use of current input signals ±20 mA, connect the current loop to screw terminals 3 and 4
(AGND) and bridge screw terminal 3 to screw terminal 7. The input resistance is approximately
150 Ohm.
The output frequency range is programmable and extends from 0.01 Hz to 100 kHz (HTL output)
and 500 kHz (TTL differential respectively RS422 output). HTL and RS422 output signals can be
used independently. Additionally, the unit provides a programmable marker pulse. The output
frequency direction can either be set by control input “UP-DOWN” or is determined by the
polarity of the input signal.
In “Motorized Potentiometer” Function Mode the UF251 can output a programmable frequency
curve, under control of inputs “UP” and “DOWN”.
In “Repeat Mode” the unit can output a cyclic frequency curve, controlled by the inputs
“UP-DOWN” and “SET”
For applications with unstable input signals the unit provides a programmable digital filter to
smoothen the output signal (floating average filter).