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3.16
Functions of the Network Primary
As stated previously, the network Primary (host) computer has all the
responsibility for network management. This consists of:
Message Flow
Control
•
Message Flow Control
•
Network Initialization
•
Error recovery
The process by which secondary stations on a “hosted” network such as
TIWAY I are invited one at a time to transmit over the physical media is
called “polling.” Polling is one of several techniques used to control the use
of a transmission media by an agreed-upon protocol between computing
devices trying to share a common path. The TIWAY I network polling
sequence is shown in Figure 3-17.
Figure 3-17 TIWAY I Network Polling Sequence
3-36
TIWAY I Overview
SIMATIC TIWAY I Systems Manual