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AC Lift System – Position Monitoring
The unit also requires an absolute measurement of lift position. This is achieved through the use of
a potentiometer. The potentiometer is turned by gearing in the lift motor, which changes the wiper
resistance.
With +3.3V DC applied across the potentiometer, the center wiper connection will be a variable
voltage (between 0 and +3.3V DC), dependent on the position of the lift. This variable voltage is
applied to the input of a 16-bit A/D converter which converts the analog voltage into a 16-bit binary
numeric representation that the processor can understand.
As the voltage returned by the potentiometer changes between 0 and 3.3V DC, the corresponding
A/D values change between 0 and 65507. In this way, the processor can keep track of where the lift
is positioned.
It is important to note that since the potentiometer is mechanically connected to the gearing of the
motor, it would be unlikely for a lift motor to go out of calibration without having some damage that
needs to be repaired, see Troubleshooting the Incline System if this occurs.
Drive / Lift System Control
The Drive/ Lift System consists of an AC drive motor controller, an AC lift motor controller and a
+8.5V DC power supply to power the console.
The electronic circuits in the console operate on +5V DC, however the lower control module sends
+8.5V DC due to the optional external equipment such as Fitlinxx, that may be connected to the
CSAFE (Communication Standard for All Fitness Equipment) port. Sending a higher voltage
(+8.5V) and regulating the voltage down to +5V DC, ensures that we can supply enough power to
both the console and the optional external equipment.
It is important to note that the lower control module is a different part number for a
120V unit than for a 240V unit.
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