msousa@276: (* Following taken directly from the IEC 61131.3 draft standard *) msousa@276: msousa@276: (* msousa@276: * An IEC 61131-3 IL and ST compiler. msousa@276: * msousa@276: * Based on the msousa@276: * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10) msousa@276: * msousa@276: *) msousa@276: msousa@276: lbessard@192: FUNCTION_BLOCK HYSTERESIS lbessard@192: (* Boolean hysteresis on difference *) lbessard@192: (* of REAL inputs, XIN1 - XIN2 *) lbessard@192: VAR_INPUT XIN1, XIN2, EPS : REAL; END_VAR lbessard@192: VAR_OUTPUT Q : BOOL := 0; END_VAR lbessard@192: IF Q THEN IF XIN1 < (XIN2 - EPS) THEN Q := 0; END_IF ; lbessard@192: ELSIF XIN1 > (XIN2 + EPS) THEN Q := 1 ; lbessard@192: END_IF ; lbessard@192: END_FUNCTION_BLOCK lbessard@192: