User Manual

Table Of Contents
Connecting a Voltage Source to Analog Inputs
Advanced Digital Motor Controller User Manual 51
1K to 10K
Ohm Pot
Internal Resistors
and Converter
+5V
Ground
A/D
20kOhm
33kOhm
FIGURE 3-9. Potentiometer wiring
Because the voltage at the potentiometer output is related to the actual voltage at the
controller’s 5V output, configure the analog input in “Relative Mode. This mode measures
the actual voltage at the 5V output in order to eliminate any imprecision due to source
voltage variations. Configure using the PC Utility.
Connecting Potentiometers for Commands with Safety band guards
When a potentiometer is used for sensing a critical command (Speed or Brake, for exam-
ple) it is critically important that the controller reverts to a safe condition in case wiring is
sectioned. This can be done by adding resistors at each end of the potentiometer so that
the full 0V or the full 5V will never be present, during normal operation, when the potenti-
ometer is moved end to end.
Using this circuit shown below, the Analog input will be pulled to 0V if the two top wires
of the pot are cut, and pulled to 5V if the bottom wire is cut. In normal operation, using
the shown resistor values, the analog voltage at the input will vary from 0.2V to 4.8V.
5K Ohm Pot
Internal Resistors
and Converter
+5V
220 Ohm
220 Ohm
Ground
A/D
20kOhm
33kOhm
FIGURE 3-10. Potentiometer wiring in Position mode