6100 BSC Programming Manual

Writing Applications that Use 6100 BSC
Relinquishing the Line
After completing a series of transmissions, a station must
relinquish the line and return it to CONTROL state. To
accomplish this task, the transmitting station makes a READ
request, instead of WRITE or WRITEREAD. This request sends an
EOT sequence and awaits a line bid.
A READ request of this kind has three common completions:
• If the other station takes the opportunity to bid for the
line, the READ request completes with the first message or
block from the bidding station.
• If the other station does not make a bid within three seconds,
the request completes with a timeout. The application may bid
for the line by making a WRITE or WRITEREAD request.
• If the other station responds with an EOT to decline the
right to bid, the request completes with notice that an
EOT was received. The application may bid for the line
by making a WRITE or WRITEREAD request.
Figure 3-8 illustrates these options.
Notice that to relinquish the line, you don't use the CONTROL
request with the EOT option. The reason is that the CONTROL
request doesn't wait for a reply, whereas the READ request
does.
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