Siemens Simatic S7-1500R System Manual page 150

Special features in program execution
● You create the user program for the S7-1500R/H redundant system in the top CPU (for
example PLC_1) in the STEP 7 project tree.
● The S7-1500R/H redundant system does not support some of the instructions the
S7-1500 CPUs. Instructions that are not supported by the S7-1500R/H redundant system
are grayed out in STEP 7 in the "Instructions" task card.
STEP 7 shows the instructions that are not supported in the program code in red. If you
compile program code with instructions that are not supported, STEP 7 outputs an error
message.
The instructions that are not supported are set out in the section Restrictions (Page 150).
● In the case of instructions with the "LADDR" block parameter, you use this parameter to
determine which of the two CPUs is the target of this instruction.
Example: To read out the I&M data of the CPU with redundancy ID 1, specify the HW
identifier 65149 (or the "Local1" system constant) at the "LADDR" block parameter of the
Get_IM_Data instruction.
You can find more information about the block parameters and the system constants of
the S7-1500R/H redundant system in the STEP 7 online help.
● In the case of a SYNCUP, the execution time of many instructions operating
asynchronously is extended.
● Temporary local data for functions (FCs): The system initialization for standard access is
identical for S7-1500R/H-CPUs as for optimized block access. Information on system
initialization for optimized block access can be found in the STEP 7 online help.
Programming style guide
The programming guidelines described in the programming style guide help you to create a
uniform program code that is easier to maintain and reuse. This means that errors can be
detected (e.g. by compiler) and avoided early on.
The programming style guide is available on the Internet
(https://support.industry.siemens.com/cs/ww/en/view/109478084).
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA
Basics of program execution
7.1 Programming the S7-1500R/H
149