Adding some comments.
(*
* (c) 2005 Mario de Sousa
*
* Offered to the public under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
* Public License for more details.
*
* This code is made available on the understanding that it will not be
* used in safety-critical situations without a full and competent review.
*)
(*
* An IEC 61131-3 IL and ST compiler.
*
* Based on the
* FINAL DRAFT - IEC 61131-3, 2nd Ed. (2001-12-10)
*
*)
(*
* This is part of the library conatining the functions
* and function blocks defined in the standard.
*
* Timer Function Blocks
* ---------------------
*
* NOTE: The timing diagrams in the comments were taken from the
* IEC 61131-3 standard.
*)
(****************************************************************
TP - pulse timing - state machine
+--------+ ++ ++ +--------+
IN | | || || | |
--+ +-----++-++---+ +---------
t0 t1 t2 t3 t4 t5
+----+ +----+ +----+
Q | | | | | |
--+ +---------+ +--+ +-------------
t0 t0+PT t2 t2+PT t4 t4+PT
PT +---+ + +---+
: / | /| / |
ET : / | / | / |
: / | / | / |
: / | / | / |
0-+ +-----+ +--+ +---------
t0 t1 t2 t4 t5
2 +---+ + +---+
STATE 1 +----+ | +----| +----+ |
0 --+ +-----+ +--+ +---------
****************************************************************)
FUNCTION_BLOCK TP
VAR_INPUT
IN : BOOL; (* first input parameter *)
PT : TIME; (* second input parameter *)
END_VAR
VAR_OUTPUT
Q : BOOL := FALSE; (* first output parameter *)
ET : TIME := T#0s; (* second output parameter *)
END_VAR
VAR
STATE : SINT := 0; (* internal state: 0-reset, 1-counting, 2-set *)
PREV_IN : BOOL := FALSE;
CURRENT_TIME, START_TIME : TIME;
END_VAR
{data__->CURRENT_TIME = __CURRENT_TIME;}
IF ((STATE = 0) AND NOT(PREV_IN) AND IN) (* found rising edge on IN *)
THEN
(* start timer... *)
STATE := 1;
Q := TRUE;
START_TIME := CURRENT_TIME;
ELSIF (STATE = 1)
THEN
IF ((START_TIME + PT) <= CURRENT_TIME)
THEN
STATE := 2;
Q := FALSE;
ET := PT;
ELSE
ET := CURRENT_TIME - START_TIME;
END_IF;
END_IF;
IF ((STATE = 2) AND NOT(IN))
THEN
ET := T#0s;
STATE := 0;
END_IF;
PREV_IN := IN;
END_FUNCTION_BLOCK
(****************************************************************
TON - On-delay timing - state machine
+--------+ +---+ +--------+
IN | | | | | |
--+ +--------+ +---+ +-------------
t0 t1 t2 t3 t4 t5
+---+ +---+
Q | | | |
-------+ +---------------------+ +-------------
t0+PT t1 t4+PT t5
PT +---+ +---+
: / | + / |
ET : / | /| / |
: / | / | / |
: / | / | / |
0-+ +--------+ +---+ +-------------
t0 t1 t2 t3 t4 t5
2 +---+ +---+
STATE 1 +----+ | +---+ +----+ |
0 --+ +--------+ +---+ +------
****************************************************************)
FUNCTION_BLOCK TON
VAR_INPUT
IN : BOOL; (* first input parameter *)
PT : TIME; (* second input parameter *)
END_VAR
VAR_OUTPUT
Q : BOOL := FALSE; (* first output parameter *)
ET : TIME := T#0s; (* second output parameter *)
END_VAR
VAR
STATE : SINT := 0; (* internal state: 0-reset, 1-counting, 2-set *)
PREV_IN : BOOL := FALSE;
CURRENT_TIME, START_TIME : TIME;
END_VAR
{data__->CURRENT_TIME = __CURRENT_TIME;}
IF ((STATE = 0) AND NOT(PREV_IN) AND IN) (* found rising edge on IN *)
THEN
(* start timer... *)
STATE := 1;
Q := FALSE;
START_TIME := CURRENT_TIME;
ELSE
(* STATE is 1 or 2 !! *)
IF (NOT(IN))
THEN
ET := T#0s;
Q := FALSE;
STATE := 0;
ELSIF (STATE = 1)
THEN
IF ((START_TIME + PT) <= CURRENT_TIME)
THEN
STATE := 2;
Q := TRUE;
ET := PT;
ELSE
ET := CURRENT_TIME - START_TIME;
END_IF;
END_IF;
END_IF;
PREV_IN := IN;
END_FUNCTION_BLOCK
(****************************************************************
TOFF - Off-delay timing - state machine
+--------+ +---+ +--------+
IN | | | | | |
---+ +--------+ +---+ +-----------
t0 t1 t2 t3 t4 t5
+-------------+ +---------------------+
Q | | | |
---+ +---+ +------
t0 t1+PT t2 t5+PT
PT +---+ +------
: / | + /
ET : / | /| /
: / | / | /
: / | / | /
0------------+ +---+ +--------+
t1 t3 t5
2 +---+ +------
STATE 1 +----+ | +---+ +----+
0 -------------+ +---+ +--------+
****************************************************************)
FUNCTION_BLOCK TOFF
VAR_INPUT
IN : BOOL; (* first input parameter *)
PT : TIME; (* second input parameter *)
END_VAR
VAR_OUTPUT
Q : BOOL := FALSE; (* first output parameter *)
ET : TIME := T#0s; (* second output parameter *)
END_VAR
VAR
STATE : SINT := 0; (* internal state: 0-reset, 1-counting, 2-set *)
PREV_IN : BOOL := FALSE;
CURRENT_TIME, START_TIME : TIME;
END_VAR
{data__->CURRENT_TIME = __CURRENT_TIME;}
IF ((STATE = 0) AND PREV_IN AND NOT(IN)) (* found falling edge on IN *)
THEN
(* start timer... *)
STATE := 1;
START_TIME := CURRENT_TIME;
ELSE
(* STATE is 1 or 2 !! *)
IF (IN)
THEN
ET := T#0s;
STATE := 0;
ELSIF (STATE = 1)
THEN
IF ((START_TIME + PT) <= CURRENT_TIME)
THEN
STATE := 2;
ET := PT;
ELSE
ET := CURRENT_TIME - START_TIME;
END_IF;
END_IF;
END_IF;
Q := IN OR (STATE = 1);
PREV_IN := IN;
END_FUNCTION_BLOCK