Siemens SIMATIC TIWAY 1 - Manual (Page 97)

HOST COMMAND SET REFERENCE
UNILINK HOST ADAPTER 5–12
USER MANUAL
5.3.4 Connect Secondaries — 04
The CONNECT SECONDARIES command logically connects one or more
secondaries to the network. Each host computer must issue this command for
the secondary devices that it will be communicating with.
Trying to connect many secondary devices at the same time could cause the host
command time-out to expire if the secondary devices do not respond in that time
limit. If this occurs, the error response will be returned and the host computer
will have to retrieve the secondary log to determine which secondary devices
were connected.
Command: 04 [aa]
Response: 04 [bb]
Usage: INITIATION
Modes: MHIU/EHA, HIU/EHA, MHIU, HIU
Parameters:
aa The secondary addresses to be connected. Specifying address FF
will attempt to connect all secondaries.
bb The secondary addresses that connected properly. If bb is 00 hex,
none of the secondaries addressed were connected.