Spectrum Controls 140 EHC 204 00sc - Manual (Page 29)

Quantum Series 140 EHC 204 00sc 140 EHC 208 00sc
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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 de-
scribed in the Configuration chapter.
Bi-Directional
The bidirectional counter requires 2 input channels. In this mode the first channel is used as the
counter input and the 2 nd channel is used to determine the count direction. The counter will incre-
ment when the Direction Channel value is 0, and will decrement when the Counter Direction Chan-
nel value is 1.
X1 Quadrature Encoder
The quadrature mode requires 2 input channels. When a quadrature encoder is attached to
inputs 1 and 2, the count direction is determined by the phase angle between inputs 1 and 2. If 1
leads 2, the counter increments. If 2 leads 1, the counter decrements. (The counter changes value
only on one edge of input 1.) The counter increments once per quadrature cycle.
X4 Quadrature Encoder
Like the X1 quadrature encoder, the count direction is determined by the phase angle between
inputs 1 and 2. If 1 leads 2, the counter increments. If 2 leads 1, the counter decrements. However,
the counter changes value on the rising and falling edges of inputs 1 and 2. The counter increments
four times per quadrature cycle.
Note: If 2 is low, the count increments on the rising edge of input 1 and decrements on the
falling edge of input 1. If 2 is high, all transitions on input 1 are ignored.
B
Forward Rotation Reverse Rotation
A
Input A
Input B
Quadrature
Encoder
B
A
x1 Count
x4 Count
1 2 3 2 1 0
1 2 3 4 5 6 7 8 9 10 11 12 11 10 9 8 7 6 5 4 3 2 1 0