Envoy ACP/XF Application Programming Manual

Normal Response Mode (NRM) Protocols
EnvoyACP/XF Application Programming Manual–132179
3-20
Responses to a Poll
If the response is an RR or RNR frame and if the response contains the proper station
identification in the address field, polling continues at the next entry. (For more
information about the RR and RNR frames, see S-Frame Command/Response Codes on
page B-7.)
If the response is any other type of frame containing the proper station identification in
the address field, polling halts, the received data and control information passes to the
application’s READ buffer, and the READ request completes. Depending upon the
content of the MCW, the application either issues additional READ requests (to accept
additional data) or issues a WRITE request to transmit an appropriate command or
response.
Table 3-2
lists and describes the errors that can be returned to a poll.
When the READ completes, bits 8 through 15 of the MCW in the READ buffer specify
the station index number. The station index refers to an entry in the station list specified
by a previous DEFINELIST procedure. (The first entry in the list is entry 0, the second
is entry 1, and so on.) Bits 8 through 15 indicate which station responded (or failed to
respond) to the poll.
Table 3-2. Errors Returned to a Poll (a READ from the Supervisor)
Condition
Code
File-System
Error Code Meaning
CCE 0 Condition Code Equal. The polled tributary responded with an
I-frame whose P/F bit was not set. The MCW indicates which
station responded. The rest of the buffer contains received data.
The tributary has more data to send. Issue another READ
request to accept the next I-frame.
CCG 8 Condition Code Greater. The polled tributary responded either
with an I-frame whose P/F was set or with the valid response
U-frame. The MCW indicates which station responded and
which type of frame was received. The rest of the buffer
contains any received data.
CCL 169 Condition Code Less. All defined tributary stations are in the
error-stop state (their addresses have been added to the
nonresponding list).
CCL 171 Condition Code Less. The particular tributary station did not
respond to the poll within the configured timeout period. The
station is added to the error-stop list. The MCW indicates
which station did not respond.
CCL 172 Condition Code Less. Improper response to the poll.
CCL 176 Condition Code Less. Applies to limited polling only. The
specified number of passes were made through the station list
and none of the tributaries had anything to send.