When one terminal on a port is enabled, then polls (UP frame)
with the go-ahead signal will be transmitted. When all terminals
are disabled no more polls will be transmitted.
Once a terminal is enabled SNRM command frames will be transmitted to
that terminal at 10 second intervals until a UA response is received.
When a terminal is disabled, no more frames will be transmitted
with that terminal's address (there is no disconnect procedure).
Response Timers |
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The T1 timer is used as in normal HDLC/NRM operation, to time
the response to a frame transmitted with the P-bit set to 1.
Because in loop mode there are usually no frames transmitted
with the P-bit set to 1 (other than TEST), there is an additional
1 second timer which is started each time an I-frame is transmitted.
If no acknowledgment has been received when this timer expires,
an RR frame with the P-bit set to 1 is transmitted to solicit a
response from the secondary station.
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