6100 BSC Programming Manual

Writing Applications that Use 6100 BSC
In short, aborting a request is a drastic action to take. It is
useful mainly in two cases:
• A request is taking so long you think it might never complete.
For instance, if a line has no connect timeout and a CONTROL
CONNECT request is taking too long, you might abort the
request in order to issue another one (like SET
CONFIGURATION).
• A path switch occurs during the request. For instance,
you issue a READ request, and the call completes with error
210. (See Appendix A, "File System Error Codes"). In this
case, the file system call has completed, but the READ
request may still be active; if you issued another READ
request to recover from the path switch, it would be rejected
because of the outstanding request. A reasonable solution to
this problem is to ABORT the current request. Then either
station can send an EOT to reset the line, and a new bid can
occur. (Another solution to this problem is to set the
BSCNONSTOPON parameter so you can reissue requests.)
ABORT can be issued at any time, with the line in any state.
ABORT leaves the line in the state in which its activity was
interrupted.
The request buffer format is:
Function := 69
Modifier := Doesn't matter
Request ID := A unique value from 1 to 32767,
application-determined
Text Out := Doesn't matter
Text In := Doesn't matter
Text := None
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