RoboteQ AX2850 - Manual (Page 82)

Installing, Connecting and Using the Encoder Mod-
82 AX2550 Motor Controller User’s Manual Version 1.9b. June 1, 2007
The actual formula is as follows:
Distance = (Destination - Counter value) / Divider
Where: divider is a configurable parameter of value 1, 2, 4, 8, 16, 32, 64 or 127
If computed distance is less than -127, then reported distance is -127
If computed distance is larger than +127, then reported distance is +127
Important Notice
Encoders do not report an absolute position value but a count that is relative to the
point where the motor shaft was at power up. It is typically necessary to have the
motors moved to a “home” position and reset the counters at that reference point.
RS232 Communication with the Encoder Module
The Encoder Module contains its own Microcontroller and firmware in Flash. When
present, it responds to a large set of dedicated commands and queries via the controller’s
serial port. See “RS232 Encoder Command Set” on page 155.
Destination= 50,050
distance at divider
50 1
25 2
12 4
6 8
3 16
1 32
0 64
0 128
Counter= 50,000
FIGURE 52. Small distance computation example
Destination= 50,000
distance at divider
127 1
127 2
127 4
127 8
127 16
127 32
78 64
39 128
Counter= 45,000
FIGURE 53. Large distance computation example