Siemens SIMATIC TIWAY 1 - Manual (Page 113)

HOST COMMAND SET REFERENCE
UNILINK HOST ADAPTER 5–28
USER MANUAL
02 = Connect Secondary. This macro type performs the
CONNECT SECONDARY function for the single secondary
device in the background mode. When the connect attempt is
complete, the MRSW will be set to 8004 hex and the exception flag
will be set. The MRSW can be retrieved with the GATHER
MACRO RESPONSE command. This macro type will be
automatically enabled when the command is processed and will
be disabled when the connect attempt is complete.
03 = Disconnect Secondary. This macro type performs the
DISCONNECT SECONDARY function for the single secondary
device in the background mode. This function performs exactly
like Macro Type 2, except a disconnect is performed. When the
disconnect attempt is complete, the MRSW will be set to 8005 hex
and the exception flag will be set.
The macro will remain undefined and an ERROR RESPONSE
will be returned if the associated secondary device is offline.
When executed, the secondary will be removed from the
secondary log and all associated macros for that secondary will be
disabled and their exception flags set.
If the HIU processing this command was given permission to
issue a DISC on the network when it was initialized, then this
command also issues a DISC directive that logically disconnects
the specified secondary from the network. This does not prevent
another HIU from reconnecting the secondary. Once a secondary
device is logically disconnected it will appear offline to all HIUs
on the network, causing the remaining network HIUs to set the
exception flag and MRSWs for any macros associated with that
secondary.