DSP222H_Manual_A
Page 2 of 17
1. General Description
The DSP-222 is a dual-channel inductive loop vehicle detector sensor unit designed to
meet the State of California, Department of Transportation, (Caltrans) specification
TSCES dated January of 1989 and the addendum dated July of 1991.
2. General Characteristics
The sensor unit incorporates a double-sided 44-pin edge connector for the connection
of power, loop inputs and call outputs and sensor unit reset. Each channel has
individual front-panel controls for setting sensitivity, frequency, and pulse/presence
mode. Each channel is also equipped with two high-intensity front-panel LEDs which
are used to indicate the detect state and fail condition of the individual channels. Call
outputs are optically isolated solid-state transistors. The sensor unit occupies one
position of a standard 170 input file. Each channel of the DSP-222 will automatically
tune to any loop and lead-in inductance between 50 and 750 microhenries with a loop
system “Q” as low as 5. The unit will detect inductance changes as small as 0.01%
∆
L/L.
3. Installation and Adjustments
The sensor unit is factory shipped with all switches set to off signifying both channels
are disabled. The MIN PRESENCE jumper J1 located on the printed circuit board is
installed forcing all detection outputs to last a minimum of 100 ms in the presence
mode. The ALTERNATE jumper J2 located on the printed circuit board is installed
forcing both channels to operate in the non-scanning mode.
a) Remove the MIN PRESENCE jumper J1 on the circuit board to allow presence
outputs of times less than 100 ms, if so desired.
b) Remove the ALTERNATE jumper J2 on the circuit board to allow both channels to
scan sequentially, if so desired.
c) Make sure that the sensor unit is firmly seated into its position in the input file.
d) Set the PULSE switch on for pulse operation. Set the PULSE switch off for presence
operation.
e) Adjust sensitivity by setting switches S1, S2, and S4 to the desired position using
standard binary coding. Sensitivity 1 is the lowest setting and Sensitivity 7 is the highest
