Siemens SIMATIC S7 System Manual page 534

Libraries
9.4 Open user communication library
Network 32: Call the DISCONNECT instruction with Req = FALSE to check the status of the
disconnect operation.
Network 33: If Done is TRUE, this means that the disconnect is complete, so try to reconnect
on the next scan.
If Busy is TRUE (this would be normal), stay in the "Disconnect Wait" state.
If there is an error, check the reason, and you may need to change state based upon the
error code.
Network 34: Exit Switch.
534
System Manual, V2.3, 07/2017, A5E03822230-AF
S7-200 SMART