Envoy Application Programming Manual

BISYNC Point-To-Point Protocol
Envoy Application Programming Manual—427159-001
3-37
Initial WRITE Operation
Initial WRITE Operation
Figure 3-5 shows the action of the local station using the standard BISYNC Point-to-
Point protocol in response to line conditions on an initial WRITE.
Figure 3-5. BISYNC Point-to-Point Initial WRITE
017CDT .CDD
Send ENQ
CALL WRITE...
2
No
No
Wait for Response
*Drop DTR
Error
= 167
Error
= 168
Timeout?
No
Yes No
Error
= 166
Station
Primary?
Text Overrun?
Wrong
Protocol?
Yes
Retry
Count = 0?
Error
= 171
Yes
Retry
Count = 0?
Error
= 171
Yes
Retry
Count = 0?
Error
= 171
WACK Recd?
Yes
Incorrect
ACKn?
EOT Recd?
RVI Recd?
Yes
Retry
Count = 0?
Error
= 172
**Repeat
Last Reply
NAK Recd?
Protocol
Error?
ACKD Recd?
Error
= 172
Error
= 175
**Retry
Count = 0?
Error
= 166
Error
= 164
Retry
Count = 0?
Retry
Count = 0?
Error
= 169
ENQ Recd?
DLE EOT
Recd?
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
No
Yes
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
No
No