ACC HDLC-NRM (SDLC) User's Guide

Chapter 3 39
Using HDLC-NRM (SDLC) Protocols
Status and Error Messages
Unsolicited Status Messages
The unsolicited status messages are used to inform the application
program of events which occur affecting communicationswith the remote
station. The status code “No error detected” is used to inform the
application that the remote station is communicating normally, either
after an enable request, or some error condition.
The status codes marked with a † contain command/response reason
code information, in the format described in Table 3-2.
The unsolicited status codes listed in following table may be sent to an
application program by the HDLC-NRM (SDLC) protocol.
Table 3-2 Unsolicited Status Codes
Unsolicited Status
Code Value
Description
IO_OK
(0)
No error detected.
Normal communications have been established or
resumed.
IO_DSBL
(1)
Terminal Disabled.
The processing for the disable request has completed.
IO_TX_TMOUT
(2)
Cable or local modem fault.
A transmit blockage exception condition exists.
IO_TX_RETRY
(4)
Too many retransmissions.
There were too many retransmissions required to
obtain a successful acknowledgment or response.
IO_INV_RESP
(9)
†
Invalid terminal response.
A command/response reject condition has been
detected by a primary station.
IO_POLL
(13)
Host has stopped polling.
For a secondary station, a poll has not been received
for the duration of the configured poll timer.