ACC HDLC-NRM (SDLC) User's Guide

Using HDLC-NRM (SDLC) Protocols
Status and Error Messages
Chapter 340
Unsolicited Status Messages
The unsolicited status messages are used to inform the application
program of events which occur affecting communications with 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.