Envoy Application Programming Manual

BISYNC Centralized Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
4-47
Programming Examples
The following conversational exchange (Example 4-17) shows the control sequences
associated with polling the network. The polling type is specified as noncontinuous; one
pass is made through the poll list with each call to the READ while the line is in the
CONTROL state. In the following example, stations 0 and 1 have nothing to send,
station 2 does.
The following conversational exchange (Example 4-18
) shows the control sequences
associated with selecting a tributary station. In the following example, station 2 is
selected.
Example 4-17. Control Sequences Associated with Network Poll
Supervisor (Local) Tributary (Remote)
CALL READ
| (poll) EOT SYN SYN PA ENQ -->
| <-- EOT (station 0)
| (poll) EOT SYN SYN PB ENQ -->
| <-- EOT (station 1)
| (poll) EOT SYN SYN PC ENQ -->
(READ completes) <-- message (station 2)
error = 0
line state = READ
MCW.<8:15> = 2
Example 4-18. Control Sequences Associated with Selection of Tributary
Supervisor (Local) Tributary (Remote)
(MCW.<8:15> := 6;)
CALL WRITE
| (sel) EOT SYN SYN Sa ENQ -->
| <-- ACK0 (station 2)
| message -->
|
|
|
(WRITE completes) <-- ACK1 (station 2)
error = 0 line state = WRITE