Spectrum Controls 1746sc-CTR4 - Manual (Page 22)

22 SLC 500 ™ 50 KHz Counter / Flowmeter Input Module
Operating Modes The module’s operating mode determines the number of available counters
and which inputs are attached to them. There are two operating modes
and their input assignments are summarized in the table below.
Table 3.2 Module operating modes
Operational Mode CTR8 (CTR4) Input Channel Configuration
Single Ended Input 8 (4) Channels – One per input
Single Ended Up/Down 4 (2) Channels - One Input / One Direction Discrete
Quadrature Input 4 (2) Channels - Two per input.
Input Configurations Input configurations determine how the 8 inputs cause the counter to
increment or decrement. The four available configurations are:
• Uni-Directional (up)
• Bi-Directional (up and down using two channels)
• X1 Quadrature Encoder
• X4 Quadrature Encoder
See the “Summary of Available Counter Configurations” for the input
configurations available for the counters, based on operating mode.
Uni-Directional
With this configuration, the input increments in an upward direction. All
8 channels may be configured in the unidirectional mode. Every clock
pulse will increment the counter on the rising edge. Note: The direction
of the counter may be inverted by setting the Count Direction bit described
in the Configuration chapter.
Bi-Directional
The bidirectional counter requires 2 input channels. In this mode one
channel is used as the counter input and the 2
nd channel is used to
determine the count direction. The counter will increment when the
Direction Channel value is 0, and will decrement when the Counter
Direction Channel value is 1.
X1 Quadrature Encoder
The quadrature mode requires 2 input channels. When a quadrature
encoder is attached to an input channel pair, A and B, the count direction
is determined by the phase angle between inputs A and B. If A leads B,
the counter increments. If B leads A, the counter decrements. (The
counter changes value only on one edge of input 1.) The counter
increments once per quadrature cycle.