Siemens SIMATIC S7-1200

Basic instructions
8.8 Program control operations
S7-1200 Programmable controller
306 System Manual, V4.2, 09/2016, A5E02486680-AK
8.8.4
RET (Return)
The optional RET instruction is used to terminate the execution of the current block. If and
only if there is power flow to the RET coil (LAD) or if the RET box input is true (FBD), then
program execution of the current block will end at that point and instructions beyond the RET
instruction will not be executed. If the current block is an OB, the "Return_Value" parameter
is ignored. If the current block is a FC or FB, the value of the "Return_Value" parameter is
passed back to the calling routine as the ENO value of the called box.
You are not required to use a RET instruction as the last instruction in a block; this is done
automatically for you. You can have multiple RET instructions within a single block.
For SCL, see the RETURN (Page 325) statement.
Table 8- 136 Return_Value (RET) execution control instruction
LAD
FBD
SCL
Description
RETURN;
Terminates the execution of the current block
Table 8- 137 Data types for the parameters
Parameter
Data type
Description
Return_Value Bool The "Return_value" parameter of the RET instruction is assigned to the ENO output
of the block call box in the calling block.
Sample steps for using the RET instruction inside an FC code block:
1. Create a new project and add an FC:
2. Edit the FC:
– Add instructions from the instruction tree.
– Add a RET instruction, including one of the following for the "Return_Value"
parameter:
TRUE, FALSE, or a memory location that specifies the required return value.
– Add more instructions.
3. Call the FC from MAIN [OB1].
The EN input on the FC box in the MAIN code block must be true to begin execution of the
FC.
The value specified by the RET instruction in the FC will be present on the ENO output of the
FC box in the MAIN code block following execution of the FC for which power flow to the
RET instruction is true.