Automating Manufacturing Systems - Process Control and ...

plc il - 18.9
Program File 2:
Label
Opcode
Operand
Comment
START:
CAL
3
(* Jump to program file 3 *)
Program File 3:
Label
Opcode
Operand
Comment
TEST:
ON:
LD
BCD_TO_INT
ST
GT
JMPC
CAL
LD
ST
CAL
LD
ST
RET
%I:000
%N7:0
100
ON
RES(C5:0)
2
%C5:0.PR
TON(C5:0)
%C5:0.DN
%O:001/00
(* Load the word from input card 000 *)
(* Convert the BCD value to an integer *)
(* Store the value in N7:0 *)
(* Check for the stored value (N7:0) > 100 *)
(* If true jump to ON *)
(* Reset the timer *)
(* Load a value of 2 - for the preset *)
(* Store 2 in the preset value *)
(* Update the timer *)
(* Get the timer done condition bit *)
(* Set the output bit *)
(* Return from the subroutine *)
Figure 18.7
An Example of an IL Program
18.4 SUMMARY
• Ladder logic can be converted to IL programs, but IL programs cannot always be
converted to ladder logic.
• IL programs use a stack to delay operations indicated by parentheses.