National Instruments 7334 - Manual (Page 38)

Chapter 5 Signal Connections
© National Instruments Corporation 5-13 7344/7334 Hardware User Manual
scan rate performance. Properly enabled, the scan rate is high enough
to support analog feedback at the highest PID sample rate.
• Analog Reference—For convenience, 7.5 V (nominal) analog
reference voltage is made available. You can use this output as a low
current supply to sensors that require a stable reference.
• Analog Input Ground—To help keep digital noise out of the analog
input, a separate return connection is provided. You should use this
reference ground connection and not Digital Ground (digital I/O
reference) or Analog Output Ground as the reference for the analog
inputs.
Wiring Concerns
For proper use of each ADC input channel, the analog signal to be
measured should be connected to the channel input and its ground reference
connected to the Analog Input Ground.
Note If an external reference voltage is used, it must not be connected to the analog
reference output, since this is an output signal only. You should, however, connect the
common of the external reference to the Analog Input Ground pin for proper A/D reference
and improved voltage measurement.
Other Motion I/O Connections
The 7344/7334 controller provides other motion I/O connections as
follows:
• Host +5 V—This is the internal +5 V supply of the host computer. This
signal is typically used to detect when the host computer is powered
and to shut down external motion system components when the host
computer is turned off or disconnected from the motion accessory.
Caution The host +5 V signal is limited to <100 mA and should not be used to power any
external devices, except those intended in the host bus monitor circuits on the UMI and
drive products.