lib/hysteresis_st.txt
author Laurent Bessard
Thu, 13 Sep 2012 16:35:10 +0200
changeset 633 73b56dc69e61
parent 276 1679f514f38a
permissions -rwxr-xr-x
Fix bug with task interval using fixed_point value for duration items
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(* Following taken directly from the IEC 61131.3 draft standard *)
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(*
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 * An IEC 61131-3 IL and ST compiler.
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 *
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 * Based on the
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 * FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
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 *
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 *)
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FUNCTION_BLOCK HYSTERESIS
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    (* Boolean hysteresis on difference *)
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    (* of REAL inputs, XIN1 - XIN2      *)
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  VAR_INPUT XIN1, XIN2, EPS : REAL; END_VAR
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  VAR_OUTPUT Q : BOOL := 0; END_VAR
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  IF Q THEN IF XIN1 < (XIN2 - EPS) THEN Q := 0; END_IF ;
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  ELSIF XIN1 > (XIN2 + EPS) THEN Q := 1 ;
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  END_IF ;
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END_FUNCTION_BLOCK
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