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Chapter 5
Signal Connections
7344 Hardware User Manual
ADC Input
5
6
7
8
You can configure each ADC channel for motion feedback, simple
A/D conversion, or both.
You can read the digital value of analog voltage on any of the
controller's eight ADC channels by using the Read ADC function. The
range of values read back and the voltage resolution for each setting
are shown in Table 5-3. The voltage resolution is given in volts per
least significant bit (V/LSB).
Table 5-3. Analog Input Voltage Ranges
Input Range
±10 V
±5 V
0–10 V
0–5 V
When configured as analog feedback, an analog sensor acts like a
limited range absolute position device with a full-scale position range
as indicated in Table 5-3. You can map any ADC channel as feedback
to any axis.
You can enable and disable individual ADC channels in software. You
should 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 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.
Table 5-2. Internal ADC Channels
Filtered +5 V
Floating (NC)
Analog Reference (7.5 V)
Analog Input Ground
Binary Values
–2,048 to 2,047
–2,048 to 2,047
0 to 4,095
0 to 4,095
5-12
Signal
Resolution
0.0049 V/LSB
0.0024 V/LSB
0.0024 V/LSB
0.0012 V/LSB
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