X25AM Programming Manual

PTP Applications
X25AM Programming Manual—527201-001
3-12
Mode 2
WRITE Request
Your application posts a WRITE to a subdevice file. The first word in the buffer is the
MCW, followed by a packet of data. WRITE COUNT should equal the size of the
packet in the buffer plus the MCW.
WRITEREAD Request
If your application is using mode 2 correctly, it will need to write various buffer formats,
such as the Call Request. If it is necessary for your application to see the network
response to the packet issued as a result of a WRITE, a WRITEREAD, rather than a
WRITE, is required. Table 3-6 shows the typical network responses when the WRITE
portion of the WRITEREAD has been successful.
If no error occurs, the WRITEREAD completes normally and the buffer contains the
network response. For example, this might be a clear packet in response to a Call
Request. Your application must process the response and determine what should be
done next.
Application Buffer Formats
The packet format used in the application buffer does not look exactly like the X.25
packet-type specification. Figure 3-2 on page 3-13 illustrates the X25AM packet buffer
and the X.25 packet specification for each packet type.
Table 3-6. WRITEREAD Network Acknowledgements
WRITE Buffer
Format Results In READ Buffer Format
Data ---> RR, RNR, Restart, Reset, Clear
Interrupt ---> Interrupt Confirmation, Restart, Reset, Clear
Reset ---> Reset Confirmation
Clear ---> Clear Confirmation
Call Request ---> Call Accepted, Restart, Clear