User Manual

Table Of Contents
Connecting Sensors and Actuators to Input/Outputs
52 Advanced Digital Motor Controller User Manual V2.0, July 8, 2019
The controller’s analog channels are configured by default so that the min and max com-
mand range is from 0.25V to 4.75V. These values can be changed using the PC configura-
tion utility. This ensures that the full travel of the pot is used to generate a command that
spans from full min to full max.
If the Min/Max safety is enabled for the selected analog input, the command will be con-
sidered invalid if the voltage is lower than 0.1V or higher than 4.9. These values cannot be
changed.
Connecting Tachometer to Analog Inputs
When operating in closed loop speed mode, tachometers can be connected to the con-
troller to report the measured motor speed. The tachometer can be a good quality brushed
DC motor used as a generator. The tachometer shaft must be directly tied to that of the
motor with the least possible slack.
Since the controller only accepts a 0 to 5V positive voltage as its input, the circuit shown
in Figure 3-11 must be used between the controller and the tachometer: a 10kOhm poten-
tiometer is used to scale the tachometer output voltage to -2.5V (max reverse speed) and
+2.5V (max forward speed). The two 1kOhm resistors form a voltage divider that sets the
idle voltage at mid-point (2.5V), which is interpreted as the zero position by the controller.
With this circuitry, the controller will see 2.5V at its input when the tachometer is
stopped, 0V when running in full reverse, and +5V in full forward.
20KOhm
1kOhm
Max Speed Adjust
10kOhm pot
1kOhm
Internal Resistors
and Converter
+5V
Ground
A/D
Ta ch
AIN
33K
Ohm
FIGURE 3-11. Tachometer wiring diagram
The tachometers can generate voltages in excess of 2.5 volts at full speed. It is important,
therefore, to set the potentiometer to the minimum value (cursor all the way down per
this drawing) during the first installation.
Since in closed loop control the measured speed is the basis for the controller’s power
output (i.e. deliver more power if slower than the desired speed, less if higher), an ad-
justment and calibration phase is necessary. This procedure is described in “Closed Loop
Speed Mode” section of this manual.