National Instruments SCB-68 - Manual (Page 41)

Chapter 3 Connecting Signals
© National Instruments Corporation 3-13 SCB-68 Shielded Connector Block User Manual
All digital timing connections are referenced to DGND. Figure 3-8
demonstrates how to connect two external timing signals to the PFI pins of
a DAQ device.
Figure 3-8. Timing I/O Connections
Noise Considerations
Environmental noise can seriously affect the measurement accuracy of
your application if you do not take proper care when running signal
wires between signal sources and the device. The following
recommendations apply mainly to AI signal routing to the device,
although they also apply to signal routing in general.
Minimize noise pickup and maximize measurement accuracy by taking
the following precautions:
• Use differential AI connections to reject common-mode noise, if
the DAQ device that you are using supports DIFF input mode.
• Use individually shielded, twisted-pair wires to connect AI signals
to the device. With this type of wire, the signals attached to the
DGND
PFI0
PFI2
I/O Connector
SCB-68
PFI0
Source
PFI2
Source