6100 BSC Programming Manual

6100 BSC Concepts and Context
You must use these values instead of the normal ASCII sequences
for ACK 0 and WACK, because BSC translates the output buffer
character by character. The ASCII sequences--for instance,
10 30 for ACK 0--would not produce the correct EBCDIC control
sequences.
ERROR HANDLING. The following parameters affect how BSC
handles errors:
BSCRETRIES<n>. This parameter specifies how often BSC repeats
an operation that has failed. The value can be from 0 through
255; the default value is 7.
The occasion for a retry may be one of the following:
• After a line bid, a message block, or another transmission,
the station receives no acknowledgement within the timeout
interval. In this case, the repeated transmission is ENQ:
"Please repeat that reply."
• After line bid, a message block, or another transmission,
a station receives a NAK, a WAK, or a garbled response.
In the case of a NAK, the retry is identical with the
previous transmission. In the case of a WAK or a
garbled response, the retry is ENQ: "Are you ready yet?"
or "Please repeat that reply."
• A station receives a bad message block or other transmission,
and sends a NAK in reply. In this case, the retry is an
effort to read the repeated transmission.
• A station receives a TTD sequence, instead of a message
block. In this case, the retry is an effort to read the
next transmission (i.e., a message block or another TTD).
BSCREADTO<n>. This parameter specifies how long a station
waits for the next message block before reporting an error to
the application. Because no retries occur in this case, the
value should be quite large.
The value expresses the timeout interval in 10-ms units. Its
range is 0 through 32767. Its default value is 3000 (30
seconds).
BSCNONSTOPON, BSCNONSTOPOFF. This parameter specifies whether,
in the case of a path switch or channel error, the protocol state
is retained or becomes undefined. If BSCNONSTOPON is in effect,
a path switch doesn't change the protocol state; the application
can retry its request. If BSCNONSTOPOFF is in effect, a path
switch leaves the state undefined, and the application must
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