ACC Error Guide

X.25 Status and Completion Messages
Introduction
Chapter 474
Introduction
X.25 may produce a wide range of buffer status codes and unsolicited
status messages, apart from the standard communications statuses.
Most of the messages are received by the zx25d driver. The ACC X.25
driver (zx25d) may also produce error messages which will be logged to
the system error logging device by zmlog. Refer to the ACC Utilities
Reference Guide for more information on zmlog. The messages logged by
the zx25d driver are explained in Chapter 12, “ZX25D System
Messages.”
Status messages are retrieved by an application using the zread()
routine. To determine whether the message retrieved is a data message
or a status message, you must examine the ZCOM message header
returned. For example, if the variable mhdp is a pointer to the ZCOM
message header returned by zread(), then you should examine the
following fields to determine if the message read was an unsolicited
status message from the X.25 subsystem:
mhdp->mid.mstype contains the value ZCOM_MSTYPE_RSLT to
indicate a response message from a local terminal. The
mhdp->mrq.mrqcode field will further indicate what
kind of response message was read.
mhdp->mrq.mrqcode contains the value ZCOM_MRQCODE_STATUS
to indicate the response message contains unsolicited
status data.
mhdp->mrq.mrqcode contains the value ZCOM_MRQCODE_CNTWR
to indicate the response message contains buffer
completion status for a control write request (zcntl).
Usually, this indicates an error condition.
mhdp->mrq.mrqcode contains the value ZCOM_MRQCODE_WRITE
to indicate the response message contains buffer
completion status for a write request (zsend). This can
indicate an error condition or notification that the data
has been transmitted and acknowledged (L2 RR) by the
remote system (DCE).
mhdp->mid.mzsrce.zlu contains the ZLU number of the X.25 link or
Virtual Circuit the status message is associated with.