Справочник Пользователя для National Instruments NI VISION PCI-8254R

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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 8254R programmed for part classification might 
drive the product selection port of a downstream NI 8254R. Alternatively, 
a PLC with information about which part is being inspected can drive the 
product selection port of the NI 8254R.

You can configure the product selection port to use ISO Input 5 as a latch. 
A rising edge on ISO Input 5 can latch the data into a data register on the 
NI 8254R. Before each inspection, the software checks the status of the 
product select inputs and reads the most recent value latched into the 
register. If ISO Input 5 is not used as a latch, it can be used as an extra bit 
of data.

In Vision Builder AI, ISO Input 5 is always designated as a latch.

Table 2-3 lists the product selection ports.

General-purpose inputs and outputs are available as both TTL and isolated 
connections. The software running on the NI 8254R can read the inputs and 
drive the outputs high or low at any time.

Table 2-3.  NI 8254R Product Selection Ports

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