Siemens Simatic S7-1500R System Manual page 211

Commissioning
9.4 Operating and system states
③
Finishing tasks
The instructions running asynchronously on the primary CPU are terminated and new ones
are accepted but not started.
From this point on, restarted asynchronous instructions are delayed until the "Copying the
working memory" phase. The "BUSY" output parameter of instructions is"1". However,
processing does not yet start.
The communication connections in the primary CPU are temporarily ended. You can no
longer delete, load, generate or compress blocks in the user program. You can no longer run
any test or commissioning functions.
Table 9- 7
210
Preparing the copying of the work memory
Primary CPU Backup CPU
S7-1500R/H redundant system
System Manual, 10/2018, A5E41814787-AA