6100 BSC Programming Manual

6100 BSC Link and Station Management
CONTROL State
A station is in CONTROL state if a connection exists, ID
exchange is complete if required, and neither station owns
the line. It is in this state that line bidding occurs.
TRANSITIONS TO CONTROL STATE. The following events cause
transitions to CONTROL state from other states:
• The application makes a CONTROL request to connect the line.
If the line is leased or does not require ID exchange, the
state changes from DISCONNECTED to CONTROL.
• The application makes its first request to read or write
from the line, without first making a CONTROL request. If the
line is leased or does not require ID exchange, the state
changes from DISCONNECTED to CONTROL. If the line requires ID
exchange, the state changes first to CIRCUIT ASSURANCE; if the
same request (like WRITEREAD) also performs ID exchange, the
state then changes from CIRCUIT ASSURANCE to CONTROL.
• The application sends an EOT sequence to end a series of
messages, or the remote station sends an EOT sequence for
the same purpose. The state changes from READ or WRITE
to CONTROL.
• The retry count is exhausted on either a READ request or
the READ part of a WRITEREAD. The corresponding status
codes are 162, 163, 172, 173, 175, and 177. (See
Section 3 for descriptions of the errors.)
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