Statement List (STL) - DCE FEL ČVUT v Praze

10.12 CC Conditional Call
Format
Description
Status word
Example
CC
Program Control Instructions
CC (conditional block call) calls a logic block if RLO=1. CC
is used to call logic blocks of the FC or FB type without parameters. CC is used in the
same way as the CALL instruction except that you cannot transfer parameters with
the calling program. The instruction saves the return address (selector and relative
address), the selectors of the two current data blocks, as well as the MA bit into the B
(block) stack, deactivates the MCR dependency, creates the local data area of the
block to be called, and begins executing the called code. The address for the logic
block can be specified absolutely or symbolically.
BR CC 1 CC 0 OV OS OR STA RLO /FC
writes: - - - - 0 0 1 1 0
STL Explanation
A I 2.0 //Check signal state at input I 2.0.
CC FC6 //Call function FC6 if I 2.0 is "1".
A M 3.0 //Executed upon return from called function (I 2.0 = 1) or directly after
A I 2.0 statement if I 2.0 = 0.
Note
If the CALL instruction calls a function block (FB) or a system function block (SFB),
an instance data block (DB no.) must be specified in the statement. For a call with the
CC instruction, you cannot assign a data block to the address in the statement.
Depending on the network you are working with, the Program Editor either generates
the UC instruction or the CC instruction during conversion from the Ladder Logic
programming language to the Statement List programming language. You should
attempt to use the CALL instruction instead to avoid errors occurring in your
programs.
Statement List (STL) for S7-300 and S7-400 Programming
A5E00706960-01 10-15