HOST COMMAND SET REFERENCE
UNILINK HOST
ADAPTER5–9
USER MANUAL
5.3.2 Br
oadcast Network Data T
ransfer — 02
The BROADCAST NETWORK DATA TRANSFER command sends the
Primitive data to all online secondary devices. The secondary device log
contains
only those secondary devices in the network that are online. However
,
this
type of
information transfer does not use the full TIW
A
Y I HDLC integrity
checks
to ensure message delivery
.
If the adapter is configured as an MHIU in EHA mode, the host applications
software must issue a POLL command for each secondary device to collect the
responses
or some responses may be lost. In any other configuration, you should
include a data element that is set in the secondary with the broadcast and
checked by the host applications software by sending a SEND NETWORK
DATA
command to determine if the broadcast message was received. The
data
element can also be checked by the secondary devices program to cause it to
perform a programmed process. This function can be more efficiently handled
in
non-MHIU/EHA networks by using macros for data acquisition.
NOTE
Before the data is broadcast, all pending TIWAY II–Frames from all HIUs will be processed. Then nofurther directives will be processed until thebroadcast completes. This could have a seriousimpact on the response time for normal networkoperations and should be used carefully.
The
following are typical uses for this command.
Time synchronization for all secondary devices. This could be used to
signal all secondaries to reset their counters at the beginning of a
production
period.
Data collection via a snapshot read. The broadcast could signal the
secondaries to move data to a designated area in the secondary device
which
will be retrieved later with a POLL or SEND NETWORK DA
TA
command.