User's Manual

28 Chapter3
Using HDLC.FRAME Protocol
Status and Error Messages
Unsolicited Status Messages
The unsolicited status messages (mrq.mrqcode = =
ZCOM_MRQCODE_STATUS) are used to inform the application
program of eventswhichoccur 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. This
could occur when an terminal has been enabled, or after an error
condition h as been cleared.
For status codes within request code 5 (unsolicited status report) bit 7
willbesettoindicatetheUP/DOWNstateoftheterminalaftertheevent
which caused the status report. Bit 7 will be set if the terminal state was
DOWN, and it will be clear if the terminal state was UP. An unsolicited
status report of zero (UP, no error detected) is used to indicate the
terminal has just come UP after being DOWN.
Z7340A ACC Interface
The following unsolicited status codes may be received by an application
program from the HDLC.FRAME protocol on a Z7340A ACC interface.
Table 3-3 Z7340A Interface Unsolicited Status Codes
Unsolicited
Status Code
Description
IO_OK No error detected.
Normal communications have been established or
resumed.
IO_DSBL Terminal Disabled
ST25XDCD Loss of DCD signal
ST25XCTS Loss of CTS signal
IO_STATS This message is sent in response to a CW_STATS control
write. The data buffer contains a x25l2stat_type structure
(defined in zcomx25.h)
IO_ALRDY_ENBL An enable request is received, while HDLC.FRAME is
already enabled. No action is taken and this unsolicited
status code is returned with the UP/DOWN bit set to
reflect the state of the port.