National Instruments NI 1450 Series - Manual (Page 53)

Chapter 4 Digital I/O Functionality
NI 1450 Series Compact Vision System User Manual 4-8 ni.com
Table 4-3 lists the product selection ports.
General-Purpose I/O
General-Purpose Inputs
General-purpose inputs are available as both TTL and isolated inputs.
At any time, the software running on the NI 1450 can read these inputs.
The primary difference between general-purpose inputs and trigger inputs
is that you cannot use general-purpose inputs to initiate a timed pulse
generator. In an application, use the general-purpose inputs to get the status
of the inputs at a given point and not to synchronize the NI 1450 system
with an external event.
An example of how to use general-purpose inputs is reading the status of
a general-purpose input as the first step in your inspection sequence and
recording that value as part of your inspection.
General-Purpose Outputs
General-purpose outputs are also available as both TTL and isolated
outputs. At any time, the software running on the NI 1450 can drive these
outputs high or low.
The primary difference between general-purpose outputs and timed pulse
outputs is that the timing of general-purpose outputs is controlled by
software rather than hardware. As a result, timing of general-purpose
outputs changes as the inspection algorithm changes, which makes
general-purpose outputs less appropriate than timed outputs for camera
control, strobe light control, and other applications that require precise
timing.
Table 4-3. Product Selection Port
Function External Connection
Data(5), rising edge latch ISO Input 5
Data(4) ISO Input 4
Data(3) ISO Input 3
Data(2) ISO Input 2
Data(1) ISO Input 1
Data(0) ISO Input 0