Siemens SIMATIC TIWAY 1 - Manual (Page 55)

OPERATION AND APPLICATION
UNILINK HOST ADAPTER 2–45
USER MANUAL
Once the action macro has successfully completed, the trigger macro behaves as
though the link never existed. If it is a repetitive macro, it will be enabled. The
trigger macro’s exception flag is also set as though the link never existed except
that it will not be set until the action macro has completed execution.
The exception flag of the action macro is only set when an error occurs for its
secondary device. If the action macro can not be executed for any reason, such as
the secondary is offline, the link will be automatically terminated. The trigger
macro will then execute as a non-linked macro. You will need to correct the
problem, then execute a recovery subroutine that will perform the following
steps.
1. Disable the trigger macro.
2. Reissue the LINK MACRO command.
3. Enable the trigger macro to start executing the link again.
The link is not automatically terminated if the trigger macro fails.
2.10.10 Network Performance
You can improve the performance of your networks by adjusting the bandwidth
of the HIUs. The statistical commands will provide a picture of transaction
bottlenecks that you can also adjust. One performance measure was already
discussed in Paragraph 2.6.2.
2.10.10.1 Network Bandwidth
The Network Manager serves as the primary in a TIWAY I network. It handles
all communications between HIUs and other secondaries. It uses Network
Manager buffers to temporarily store requests and responses before they are
forwarded to the appropriate devices. These buffers are divided between the
HIUs on the network. The number of buffers assigned to a particular HIU its
bandwidth. The more buffers allocated to the HIU, the more requests the
Network Manager function can simultaneously process for that HIU.