6100 ADCCP Programming Manual

Station States and Transitions
ADCCP Link and Station Management
069225 Tandem Computers Incorporated 2–11
FRMROUT Occurs when the local station has transmitted a FRMR or RSPR frame
and is waiting for a mode-setting frame or request to clear the
condition. (A primary station expects a MODE SET request from the
application. A secondary station expects a mode-setting frame to
arrive on the line.) Application requests to send data will fail, and
arriving frames for the station are discarded until the mode-setting
frame arrives. The ADCCP protocol module responds to an arriving
frame with the poll bit set by sending another FRMR or RSPR frame
with the poll bit set. (A combined primary substation sends a RSPR.
A secondary substation sends a FRMR.)
LRNR Occurs when an application requests a station RNR, demanding that
the local station refuse incoming I-frames. When an application
requests a station RNR, the application can send data to the remote
station, but the ADCCP protocol module discards I-frames arriving
from the remote station. The local station sends RNR supervisory
frames, instead of the RR frames it would send if it wished to receive
data.
NOPOLL Occurs when an application requests it. In this situation, the
application’s requests to send data fail, and all incoming frames are
discarded. The local station behaves as if it were dead, except that the
station remains in the same state it was in prior to its “dead” behavior.
An application request can clear the NOPOLL condition.
REJOUT Occurs when the local station has sent a REJ frame and is expecting
the arrival of the rejected frame. Incoming frames are discarded until
the expected frame arrives. If the T1TIMER expires before the
expected frame arrives, a primary or combined station transmits an
RR frame with the poll bit set. If the permitted number of retries is
exhausted:
The ERRORSTOP condition occurs.
The station state changes to LDS (DEAD).
SREJOUT Occurs when the local station has sent an SREJ frame and is expecting
the arrival of the rejected frame. Incoming frames are held pending
receipt of the expected frame. If the T1TIMER expires before the
expected frame arrives, ADCCP discards the frames that were being
held and sends a REJ to the remote station.