1 FUNCTION_BLOCK CMD_MONITOR

     2  VAR_INPUT AUTO_CMD : BOOL ; (* Automated command *)

     3           AUTO_MODE : BOOL ; (* AUTO_CMD enable *)

     4             MAN_CMD : BOOL ; (* Manual Command *)

     5         MAN_CMD_CHK : BOOL ; (* Negated MAN_CMD to debounce *)  

     6           T_CMD_MAX : TIME ; (* Max time from CMD to FDBK *)

     7                FDBK : BOOL ; (* Confirmation of CMD completion     

     8                                 by operative unit *)               

     9                 ACK : BOOL ; (* Acknowledge/cancel ALRM *)         

    10  END_VAR

    11  VAR_OUTPUT CMD : BOOL ;   (* Command to operative unit *)

    12            ALRM : BOOL ;   (* T_CMD_MAX expired without FDBK *)

    13  END_VAR

    14  VAR CMD_TMR : TON ;    (* CMD-to-FDBK timer *)

    15      ALRM_FF : SR ;     (* Note over-riding S input: *)

    16  END_VAR                (* Command must be cancelled before

    17                               "ACK" can cancel alarm *)

    18  (* Function Block Body *)

    19     CMD := AUTO_CMD & AUTO_MODE

    20           OR MAN_CMD & NOT MAN_CMD_CHK & NOT AUTO_MODE ;

    21     CMD_TMR (IN := CMD, PT := T_CMD_MAX);

    22     ALRM_FF (S1 := CMD_TMR.Q & NOT FDBK, R := ACK);

    23     ALRM := ALRM_FF.Q1;

    24 

    25 END_FUNCTION_BLOCK