Вот простейший код, который тормозит на определённых шагах:
Код:
PROGRAM PLC_PRG
VAR
	targetSpeed, tmpSpeed, resultSpeed: INT (1..18);
	isAccStep: BOOL;
	delay: TON;
END_VAR

IF targetSpeed <> tmpSpeed THEN
	delay(IN := isAccStep, PT := T#1s);
	tmpSpeed := tmpSpeed + LIMIT(-1, targetSpeed - tmpSpeed, 1) * (BOOL_TO_INT(delay.Q) + BOOL_TO_INT(NOT isAccStep));
END_IF

isAccStep := tmpSpeed = 11 OR tmpSpeed = 14 OR tmpSpeed = 17;

IF targetSpeed = tmpSpeed OR isAccStep THEN
	resultSpeed := tmpSpeed;
END_IF