Chapter 5
Signal Connections
NI PCI-7342 Hardware User Manual
5-14
ni.com
You can configure each ADC channel for motion feedback, simple
A/D conversion, or both.
You can use the Read ADC function to read the digital value of analog
voltage on any of the eight ADC channels on the controller. Table 5-3
shows the range of values read back and the voltage resolution for each
setting. The voltage resolution is in volts per least significant bit
(V/LSB).
As indicated in Figure 5-3, when configured as analog feedback, an
analog sensor acts like a limited range absolute position device with a
full-scale position range. You can map any ADC channel as feedback
to any axis.
You can enable and disable individual ADC channels in software.
Disable unused ADC channels for the highest multiplexer 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 available. You can use this output as a low-current
supply to sensors that require a stable reference.
•
Analog Input Ground
—This separate return connection is available
to help keep digital noise out of the analog input. Use this reference
ground connection and not Digital Ground (digital I/O reference) or
Analog Output Ground as the reference for the analog inputs.
Table 5-3.
Analog Input Voltage Ranges
Input Range
Binary Values
Resolution
±10 V
–2,048 to 2,047
0.0049 V/LSB
±5 V
–2,048 to 2,047
0.0024 V/LSB
0–10 V
0 to 4,095
0.0024 V/LSB
0–5 V
0 to 4,095
0.0012 V/LSB
