Trackmaster FVX325, Field Service Manual

Page: 117 / 205

TRACKMASTER
9-2
FVX, TMX Series Service Manual August, 2006
SOFTWARE REQUIREMENTS
SPEED CONTROL
There are two outputs and one input required for speed control. The belt enable output must
be fully energized to put the belt into a run mode. The speed control output is a 25hz 1024
count pulse width modulated output which is filtered to produce an analog voltage referenced
to a fixed voltage supplied by the inverter. The belt speed is measured by sampling the state
of a magnetic reed switch input attached to the motor shaft.
Based on calibration, the speed is controlled by outputting an analog speed reference to the
inverter and enabling the belt run output. The speed input is averaged over a two second
period to provide measured speed accuracy of 0.01mph or less. If an over speed or under
speed condition is measured, the belt will shut off automatically. An over speed condition is
defined as 1mph over the current target speed. An under speed condition is defined as 1mph
below the current target speed. If the measured speed is within range, it is used to make
minor adjustments to the speed output if it is determined that the actual speed and measured
speed differ by more than 0.08 mph. These small adjustments (1:1024) are only allowed to
be at 4 second intervals to provide for the settle time of the motor inverter output and heavily
averaged speed input after making the previous adjustment.
ELEVATION CONTROL
The elevation position is constantly monitored by counting and recording changes in the state
of the elevation microswitch sensor. Each debounced state is counted as positive if the
elevation motor is engaged in the up direction and negative if it is engaged in the down
direction. Using this count and the calibration numbers, the elevation position is controlled
by turning on the motor in the desired direction and counting until the target number of
counts has been reached. At that time, the elevation motors are disengaged until another
setpoint position is requested.
COMMUNICATION
Hardware
- DB9 Connector 9 pin PC/AT Style
Pin Description
2 Transmit Data
3 Receive Data
5 Signal Ground
- RS232 (+/- 10V)
- 4800 Baud
- No Parity
- 8 Data Bits
- 1 Stop Bit
- Full Duplex