Siemens SIMATIC S5 Manual page 260

Application of the Function Block
Using the temperature controller module in multiprocessor operation
(relevant for the S5-135U and S5-155U)
If the temperature controller module is operated in a PLC with several CPU modules, you must
ensure that the module can only be addressed by one CPU module.
Interrupting the user program by event and time-driven interrupts in the S5-115U
The user program is always interrupted at command boundaries. If interrupt OBs are programmed
in the user program, in which the scratchpad flag area (flag bytes FY200 to FY255) is used, make
sure that this flag area is saved and reloaded before exiting the interrupt OB. The function block
FB 162 must not be called in the interrupt OBs.
Start-up procedure with the S5-115U
Cyclic program execution following "cold restart" (OB 21) and "automatic warm restart" (OB 22)
begins at the start of OB 1.
The function block is normally called with the command KS (cold restart) following a cold restart
and with the command PA (assign parameters) following an automatic warm restart.
If neither "PA" or "KS" are executed following an automatic cold restart, the IP is placed in a queue.
Interrupting the user program by event and time-driven interrupts with the S5-135U
The user program is interrupted at block boundaries or at command boundaries if data block DX0
has suitable parameters assigned.
If interrupt OBs are programmed in the user program in which the scratchpad flag area (flag bytes
FY200 to FY255) is used, make sure the flag area is saved and reloaded before exiting the interrupt
OB. The same applies to the operating system data RS60 and RS61.
Function block FB162 must not be called in the interrupt OBs.
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