ACC X.25 Protocol User's Guide

ZX25D X.25 Protocol Driver
Virtual Circuit Definitions
Chapter 350
Configuration Parameters Definition
The following configuration values are currently defined for use in X.25
configuration as a replacement for the POLL and SELECT address
fields. These values are used as a symbolic way of configuring the
associated two 16-bit hexadecimal values. For example,
X25_VC_DFLT_Q_D can be used to set the POLL address to 0 and the
SELECT address to 0. If a particular desired configuration value is not
provided by these values, then two hexadecimal values can be used
instead.
X25_VC_DFLT_Q_D 0000h 0000h
X25_VC_Q0_D0 1000h 0000h
The POLL and SELECT words configure the following parameters for
the X.25 Virtual Circuit (terminal type 26) configuration:
D provide D-bit capability (end-to-end packet
acknowledgment) for automatic call packet
Set D is set to indicate above value should be used (else use
default in X.25 Link Terminal’s Option word)
Logical
Channel No. Logical Channel Number is defined here for PVCs only
Packet Size only set for PVCs
Window Size only set for PVCs
They are formatted in the POLL and SELECT words as follows:
Poll Word for X.25 PVC Configuration
D 1 => Allow data packets with the D-bit set to 1 to be
sent over this PVC.
STD 1 => take D value from bit 14 of POLL word, else take
D value from X.25 Link Option word D bit
LCN PVCs Set for PVCs as per subscription
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
DST
D
Logical Channel Number (LCN)