The Cycle Timer
Owners Manual
1.6 Logic Input Installation
If your PCT was ordered with the optional count push button kit, or the optional photo-eye kit, some / all of the logic
wiring you need may have already been completed by the factory. However you may still wish to review this
section for information on how the PCT logic inputs are operated.
The PCT's logic inputs are designed to be activated by connecting an input screw terminal (HOLD, T-RST,B-RST,
or CNT) to a ground screw terminal (GND). Typically this is accomplished with a push button switch, whisker
switch, or mechanical relay contact. However it can also be done with an NPN or CURRENT SINKING photo-eye,
proximity sensor, or solid state relay.
The digital logic inputs are sampled once every 10mS, and then processed by a simple software debounce
algorithm. Transient conditions lasting less than 30mS are rejected as noise. Due to this filtering, the maximum
allowed count rate is 10Hz, with a 50% duty cycle waveform (50mS On Time, 50mS Off Time), and the minimum
width of a reset pulse is 50mS.
If your PCT was purchased with the optional logic input extension cable, the factory will have already installed
wiring that provides the CNT-1 and HOLD inputs on a six foot extension cable terminated in a four pin Molex
Minifit Jr connector as diagrammed below.
Even if the logic input extension cable is installed, it is still permissible to use the customer logic input connector to
connect other devices to the PCT. The CNT-1 wire of the extension cable is connected in parallel with the CNT-1
screw terminal on the customer logic input connector.
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INPUT
INPUT
GND
GND
PPT Logic Input
PPT Logic Input
Customer Wiring
Customer Wiring
Push Button
Switch
NPN
Transister
Optional Logic Input
Extension Cable Pinout
