Wenn du ein Handybord hast, dann solltest du auch ein Handbuch zu IC dem Betriebssystem haben.
Meine letzte Version ist: IC 5.0.4 Build on Mar 4. 2005, 15:13:24
http://www.kipr.org/
http://www.botball.org/
http://www.sourceforge.net/projects/interactive-c/

Ich hab mal in der Hilfe bei Encoder geschaut.

Encoders Index
The enable_encoder() library function is used to start a process which updates the transition count for the encoder specified. The encoder library functions are designed for sensors connected to (digital) ports 7,8,12,13 on the Handyboard (The corresponding <encoder#> values are 0,1,2,3), or in 1,2, or 3 on the RCX. Every enabled encoder uses a lot of the processor -- so don't enable an encoder unless you are going to use it, and never put an enable statement inside of a loop.

enable_encoder(<encoder#>);
/* turns on the specified encoder (either 0,1,2, or 3 which are
plugged into digital ports 7,8, 12 & 13 respectively, on the HB).
This should be done only once - never enable an already enabled
encoder. If an encoder is not enabled, read_encoder will
always return 0. */
disable_encoder(<encoder#>)
/* turns off the specified encoder */
reset_encoder(<encoder#>)
/* sets the specified encoder value to 0 */
read_encoder(<encoder#>)
/* returns an int that is the current value of the specified
encoder */