Chapter 3
Digital I/O Functionality
©
National Instruments Corporation
3-7
NI CVS-1450 Series User Manual
Quadrature Encoder
The quadrature encoder uses ISO Input 6 for its Phase A input and
ISO Input 7 for its Phase B input. Encoder speed is limited by the speed of
the isolated inputs. Each isolated input can change at a maximum rate of
100 kHz, making the maximum encoder rate 400,000 counts/s.
The quadrature encoder can also be used as a timebase for the pulse
generation delay.
Figure 3-4 shows a rising edge trigger and a low pulse with a quadrature
encoder delay and a microsecond width.
Figure 3-4.
Rising Edge Trigger, Low Pulse with a Quadrature Encoder Delay
Product Selection Port
The product selection port consists of a group of five isolated digital
inputs that the software running on the NI CVS-1450 device reads
simultaneously. You can program the NI CVS-1450 device to switch
between up to 32 (2
5
) inspection sequences for different parts on an
assembly line.
Based on the input to the product selection port, you can configure the
application software to run the appropriate inspection sequence. For
example, an upstream NI CVS-1450 device programmed for part
classification might drive the product selection port of a downstream
NI CVS-1450 device. Alternatively, a PLC with information about
which part is being inspected can drive the product selection port of the
NI CVS-1450 device.
Phase A
Phase B
Delay
Width
Trigger
Low Pulse
