Statement List (STL) - DCE FEL ČVUT v Praze

B.6 Example: Word Logic Instructions
Heating an Oven
Programming Examples
The operator of the oven starts the oven heating by pushing the start push button.
The operator can set the length of time for heating by using the thumbwheel switches
shown in the figure. The value that the operator sets indicates seconds in binary
coded decimal (BCD) format.
Oven
Heat
Q 4.0
Statement List
7....
X X X X 0 0 0 1
Thumbwheels for setting BCD digits
Start push button I 0.7
4 4 4
...0 7...
...0
1 0 0 1 0 0 0 1
Bits
IW0
IB0 IB1
Bytes
System Component Absolute Address
Start Push Button I 0.7
Thumbwheel for ones I 1.0 to I 1.3
Thumbwheel for tens I 1.4 to I 1.7
Thumbwheel for hundreds I 0.0 to I 0.3
Heating starts Q 4.0
STL Explanation
A T1 //If the timer is running,
= Q 4.0 //then turn on the heat.
BEC //If the timer is running, then end processing here. This prevents timer
T1 from being restarted if the push button is pressed.
L IW0
AW W#16#0FFF //Mask input bits I 0.4 through I 0.7 (that is, reset them to 0). The
time value in seconds is in the low word of accumulator 1 in binary coded
decimal format.
OW W#16#2000 Assign the time base as seconds in bits 12 and 13 of the low word of
accumulator 1.
A I 0.7
SE T1 //Start timer T1 as an extended pulse timer if the push button is
pressed.
Statement List (STL) for S7-300 and S7-400 Programming
A5E00706960-01 B-13