National Instruments NI PCI-8254R - Manual (Page 23)

Chapter 2 Digital I/O
NI PCI-8254R User Manual 2-12 ni.com
Considerations When Connecting the Digital I/O
The isolated trigger inputs on the NI 8254R are current sinking and
optically isolated. The following are considerations you need to make when
connecting the digital I/O.
Wiring an Isolated Input to a Sourcing Output Device
You can wire an isolated input to a sourcing output device, as shown in the
following figure. Refer to the NI PCI-8254R Quick Start Guide for
switching thresholds and current requirements.
Caution Do not apply a voltage greater than 30 VDC to the isolated inputs. Doing so could
damage the NI 8254R.
The following figure shows an example of connecting an isolated input to
a sourcing output device.
Vcc
Sourcing
Output
Device
V
Current
Limiter
C
NI 8254R
Input