Envoy Application Programming Manual

ADM-2 Multipoint Supervisor Protocol
Envoy Application Programming Manual—427159-001
7-26
READ Procedure
Table 7-8 shows file-system errors that may occur on an initial READ.
Example 7-9. Initial READ (Line in CONTROL State)
Application Process Terminal
line state = CONTROL
CALL READ(...)
| EOT a1 a1 p ENQ -->
| <-- EOT
| EOT a2 a2 p ENQ -->
| . <-- EOT
| . .
| . .
| EOT an an p ENQ --> .
| message
(READ completes)
error = 0
line state = READ
MCW.<8:15> contains entry number for station "n"
Note. The message from the terminal is not acknowledged by the initial READ. The following
READ acknowledges the message
Table 7-8. Initial READ File-System Errors (page 1 of 2)
Error Numbers Description Resultant Line Number
0 No error. A station responded with a
message. Message is returned to the
buffer of the application process.
READ
160 Request is invalid for device state;
protocol error.
unknown
161 Impossible event occurred for line state.
unknown
171 No response received. The terminal
indicated in the message control word did
not respond to the poll sequence within
the line’s timeout period. The terminal is
placed in the nonresponding terminal list.
CONTROL
172 Reply not proper for protocol. The data
received while waiting for a response to
the poll sequence was not proper for the
ASCII protocol.
CONTROL
173 Transmission error. The message received
was in error and a NAK sequence was
sent the number of times specified by the
retry value.
CONTROL