I/O For Normal Operation; Trigger Inputs; Timed Pulse Output - National Instruments NI PCIe-8255R User Manual

I/O for Normal Operation

Trigger Inputs

Timed Pulse Output

© National Instruments Corporation
The following sections describe I/O functions that are available on the
NI 8255R during normal operation.
Trigger inputs are available from both TTL inputs and isolated inputs. You
can use these trigger inputs to synchronize the NI 8255R with an external
event, such as the assertion of a signal generated by a proximity sensor or
a PLC, to indicate that an inspection item is passing in front of the camera.
The NI 8255R can use this input to initiate a timed pulse for camera control,
lighting control, encoder pulse counting, and result output timing.
For more information about creating a timed pulse output, refer to the
Timed Pulse Output section.
TTL Input 0, TTL Input 1, TRIG 0, ISO Input 6, ISO Input 7, ISO Input 8,
and ISO Input 11 can alternatively function as general-purpose inputs.
ISO Input 5 can alternatively function as a latch for the product selection
port.
The NI 8255R is capable of timed pulse output on six different digital
outputs, which provides precise control over time-critical signals, such as
camera exposure. This section describes the various uses for the timed
pulse output and the parameters you can set to control these outputs.
Uses for timed pulse output include controlling camera reset and exposure,
controlling strobe lighting, operating plungers on an assembly line, and
communicating with PLCs. You can configure the start of the pulse output
generation to occur from software or from a rising or falling edge of a
trigger input.
In addition to controlling the timing of pulse output, you can also configure
the polarity of the output signal, resulting in a high-true or low-true signal.
Based on the polarity setting, the output signal asserts after the appropriate
delay time and de-asserts after the configured pulse width. You can set the
delay time in microseconds or in quadrature encoder counts from the start
signal—either a hardware trigger or a software command. Width is always
configured in microseconds.
2-5
Chapter 2 Hardware Overview
NI PCIe-8255R User Manual