6100 ADCCP Programming Manual

Link States and Transitions
ADCCP Link and Station Management
069225 Tandem Computers Incorporated 2–5
Figure 2-3. Link States and Transitions
DISC^IDLE
DISC^WAIT
READY^IDLE
Line Downloaded
ADCCP Asserts DTR
Modem Asserts DSR
Frame Queued
for Output
Frame
Sent
DSR Timeout
Disconnect
Request or
Modem Error
XMIT
009
Receives Data
DISC^IDLE State The DISC^IDLE state occurs after the LIU has been downloaded and started with
CMI, but before ADCCP has asserted a DTR signal to the modem. The DISC^IDLE
state can also occur if the modem was reset by an application request or link error.
In the case where the LIU has been downloaded and started with CMI, the DISC^IDLE
state persists while the application opens the line, possibly sets or modifies the line’s
configuration, and starts the line with the START request. If the line is a leased line,
the START request causes a state transition. If the line is a switched line, the
application issues a START request, then a MODEM CONTROL request.
If a STOP request puts the line in the DISC^IDLE state, the state persists until the
application issues either a START request or a START request and then a MODEM
CONTROL request. If a MODEM CONTROL request caused the line to be
disconnected, the state persists until the application makes a MODEM CONTROL
connect request.
DISC^WAIT State In the DISC^WAIT state, the application has issued a START request (for a leased line)
or a MODEM CONTROL connect request (for a switched line). The state lasts until the
modem asserts DSR or until the application issues a disconnect request.