Envoy Application Programming Manual

BISYNC Centralized Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
4-27
READ Procedure
Table 4-10 lists the file-system errors that may occur on an initial READ.
Example 4-7. Initial READ (Line in CONTROL State)
Supervisor (Local) Tributary (Remote)
line state = CONTROL
CALL READ(...)
| EOT SYN-poll addr 1-ENQ -->
| <-- EOT
| EOT SYN-poll addr 2-ENQ -->
| <-- EOT
| .
| . .
| . .
| .
| EOT SYN-poll addr n-ENQ -->
| <-- message 1
|
(Initial READ completes)
error = 0
line state = READ
MCW.<8:15> contains the entry number for station "n"
Note. The initial message from the tributary is not acknowledged by the initial READ. The sub-
sequent READ acknowledges the initial message.
Table 4-10. Initial READ File-System Errors (page 1 of 2)
Error Number Description Resultant Line State
0 No error. A station responded with a message.
The message is returned to the application pro-
cess's buffer.
READ
160 Request is invalid for device state; protocol
error.
unknown
161 Impossible event occurred for line state. unknown
162 Operation timed out. No message was received
within the timeout or retry limits.
CONTROL
171 No response received. The station indicated in
the message control word did not respond to the
poll sequence within the line's timeout period.
The station is placed in the nonresponding sta-
tion list.
CONTROL