ACC X.25 Protocol User's Guide

X.25 Application Programming
Sending and Receiving Data
Chapter 478
Sending Interrupt Data
To send an X.25 interrupt data packet, you should use the ZCOM API
call zx25send_int().
If the X.25 link has been configured for 1980 operations, you may send
only one byte of interrupt data. If you are using 1984 or later, you may
send up to 32 bytes of interrupt data. After sending an interrupt data
packet, you are not allowed to send another interrupt data packet until
the interrupt confirmation status is received, or the confirmation times
out.
For more information on using the zx25send_int() API call, refer to the
call description later in this chapter.
NOTE Previous releases of the ACC X.25 Protocol provided a mechanism to
send X.25 interrupt data packets via a zcntl() call. This mechanism is
now obsoleted, but remains available in this release for backwards
compatibility.
Application Use of the M, Q, & D-Bits
Messages can be sent and received with the D, M, and Q bits set. The
application program uses the message tag byte in the ZCOM message
request header (zmrq_type). The tag byte is defined in this structure as
field mrqtag. The tag byte should be set in messages sent and examined
in messages received.
Table 4-1 Tag Byte in Send Messages
7 6 5 4 3 2 1 0
QD M
Table 4-2 Tag Byte in Receive Messages
7 6 5 4 3 2 1 0
QD M Q