Envoy Application Programming Manual

ADM-2 Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
7-30
WRITE Procedure
The call to the WRITE procedure completes when the terminal acknowledges the
message. The successful transmission of the message is indicated by a condition code of
CCE upon completion of the WRITE.
WRITE of Special Message (Line in READ State)
A WRITE of a special message while the line is in the READ state (Example 7-14)
causes Envoy to acknowledge the preceding message and read the associated EOT
indication, then to transmit the message from the buffer of the application process (the
selection sequence is skipped). The call to the WRITE procedure completes when a
terminal acknowledges the message. The successful transmission of the message is
indicated by a condition code of CCE upon completion of the WRITE.
Example 7-13. WRITE of Normal Text Message (Line in READ State)
Application Process Terminal
line state = READ
MCW.<6> = 0 (message type = normal)
CALL WRITE(...)
|
| ACK -->
| <-- EOT
| (sel) EOT a1 a1 q ENQ -->
| <-- ACK
| message -->
| <-- ACK
(WRITE completes)
error = 0
line state = CONTROL
Example 7-14. WRITE of Special Message (Line in READ State)
Application Process Terminal
line state = READ
MCW.<6> = 1 (message type = special,
message = sequential select)
CALL WRITE(...)
| ACK -->
| <-- EOT
| EOT a1 a1 ra2 a2 r.an an s STX-text-ETX -->
|
| <-- ACK
(WRITE completes)
error = 0
line state = CONTROL