BECKHOFF CX1100-000x - Manual (Page 23)

Product overview
Embedded PC 21
PROGRAM MAIN
VAR
Taster AT %IB0 : USINT;
END_VAR
A simple CASE statement can then be used to evaluate the switch, and the desired function can be initiated, e.g.:
CASE Taster OF
0: ACTION := NONE;
1: ACTION := UP;
2: ACTION := DOWN;
4: ACTION := LEFT;
8: ACTION := RIGHT;
16: ACTION := SELECT;
END_CASE;
In this case, "ACTION" is a newly defined ENUM type. It is also possible for the desired action to be activated
immediately.
The sum of the numerical values is used for the combined functions. In other words, UP (1) and RIGHT (8) would be
8 + 1 = 9. In this way, only sensible combinations are possible. In other words, switch positions that are opposite to
one another cannot be selected without damaging the switch.
If the programmer does not want to carry out the evaluation, the TwinCAT System provides a library function that
implements conversion of the switch input into an ENUM type. For this purpose, the library for the CX Systems,
TcSystemCX.lib, must be integrated into the library manager. The function is called "F_CXNaviSwitch(iCX1100_IN :
USINT)", and returns an ENUM type. This encodes the direction of the switch that has been pressed as names, for
example e_CX1100_NaviSwitch_MIDDLE for <Middle>. The full list of valid possibilities is:
 e_CX1100_NaviSwitch_IDLE
 e_CX1100_NaviSwitch_MIDDLE
 e_CX1100_NaviSwitch_TOP
 e_CX1100_NaviSwitch_TOPRIGHT
 e_CX1100_NaviSwitch_RIGHT
 e_CX1100_NaviSwitch_BOTTOMRIGHT
 e_CX1100_NaviSwitch_BOTTOM
 e_CX1100_NaviSwitch_BOTTOMLEFT
 e_CX1100_NaviSwitch_LEFT
 e_CX1100_NaviSwitch_TOPLEFT
 e_CX1100_NaviSwitch_MIDDLE_TOP
 e_CX1100_NaviSwitch_MIDDLE_TOPRIGHT
 e_CX1100_NaviSwitch_MIDDLE_RIGHT
 e_CX1100_NaviSwitch_MIDDLE_BOTTOMRIGHT
 e_CX1100_NaviSwitch_MIDDLE_BOTTOM
 e_CX1100_NaviSwitch_MIDDLE_BOTTOMLEFT
 e_CX1100_NaviSwitch_MIDDLE_LEFT