// 状态机
CASE State OF
0: // 初始状态
Running := FALSE;
Finished := FALSE;
IF Start THEN
State := 1;
END_IF
1: // 启动状态
Running := TRUE;
Finished := FALSE;
IF Stop THEN
State := 0;
ELSIF StepMode OR NOT Step THEN
State := 2;
END_IF
2: // 单步状态
Running := TRUE;
Finished := FALSE;
IF Stop THEN
State := 0;
ELSIF NOT StepMode AND Step THEN
State := 1;
END_IF
END_CASE
// 判断是否切换单步模式
IF NOT StepMode AND Step THEN
StepMode := TRUE;
ELSIF StepMode AND NOT Step THEN
StepMode := FALSE;
END_IF[/code]