Envoy Application Programming Manual

BISYNC Point-To-Point Protocol
Envoy Application Programming Manual—427159-001
3-18
READ Procedure
Note that the initial message from the remote station is not acknowledged by the initial
READ. The subsequent READ acknowledges the initial message.
A timeout (Example 3-2
) can occur while the local station is waiting for a line bid from
the remote station. A timeout occurs if the remote does not bid for the line within the
specified timeout and retry settings. A timeout error causes the call to READ to
complete with a CCL indication. A subsequent call to FILEINFO returns an error 162
(operation timed out).
The file-system errors shown in Table 3-10
can occur on an initial READ.
Example 3-1. Initial Read (Line in CONTROL State)
Local Remote
line state - CONTROL
CALL READ (...) |
| <--ENQ (bid)
| ACKD -->
|
| <--message 1
(READ completes)
error = 0
line state = READ
Example 3-2. Timeout on Initial Read
Local Remote
line state - CONTROL
CALL READ (...)
|
| (no bid)
|
(READ completes)
error = 162
line state = CONTROL
Table 3-10. Errors on Initial READ for BISYNC Point-to-Point (page 1 of 2)
Error
Number Description
Resultant Line
State
0 No error. Message is returned to buffer of the application
process.
READ
140 Modem error. READ
160 Request is invalid for device state; protocol error. unknown
161 Impossible event occurred for line state. unknown