Envoy Application Programming Manual

BISYNC Point-To-Point Protocol
Envoy Application Programming Manual—427159-001
3-38
Initial WRITE Operation
Figure 3-6 shows the action of the local station using the SWIFT BISYNC Point-to-
Point protocol in response to line conditions on an initial WRITE.
Figure 3-6. SWIFT Point-to-Point Initial WRITE
018CDT .CDD
Send ENQ
CALL WRITE...
2
No
Wait for Response
Error
= 167
Error
= 168
Timeout?
Text Recd?
Yes
Retry
Count = 0?
Error
= 177
Yes
Retry
Count = 0?
Error
= 171
Yes
Incorrect
ACKn?
EOT Recd?
RVI Recd?
Yes
Retry
Count = 0?
Error
= 172
NAK Recd?
Protocol
Error?
ACKD Recd?
Error
= 171
Error
= 175
Retry
Count = 0?
Retry
Count = 0?
Yes
Yes
No
No
Yes
See
Continuation
WRITE
Yes
No
No
No
No
No
Yes
Yes
Yes
No
No
No
Yes
Yes
* Data Terminal Ready if Switched Line
** The SWIFT protocol has fixed values for
retry count:
30 for the WACK ENQ sequence and 3 for
repeat last reply.
No
*Drop DTR
No
Yes No
Error
= 166
Station
Primary?
Wrong
Protocol?
Yes
Retry
Count = 0?
Error
= 171
WACK Recd?
**Repeat
Last Reply
**Retry
Count = 0?
Error
= 166
Error
= 164
Error
= 169
ENQ Recd?
DLE EOT
Recd?
Yes
Yes
No
Yes
Yes
No
Yes
Text Overrun?
Yes
Retry
Count = 0?
Error
= 171
Yes
No
No
No
No
No