User`s guide

76 DC 900-1516D

ICP2432 User’s Guide for OpenVMS Alpha (DLITE Interface)

4.3.2.1 Node 1

Node 1 is the primary node number to which all data is written. The VMS driver allows

multiple programs to write to the same node number. The P4 parameter in the QIO call

should be 0x0101 for all writes.

4.3.2.2 Node 2

Node 2 is the alternate write node. Its use varies per protocol. In some documents,

node 2 is referred to as the “express node” for sending priority packets to the ICP. How-

ever, for most protocols this node is treated the same as node 1. Unless your protocol

programmer’s guide says otherwise, you should not use node 2 to write data packets to

the ICP. You should use node 2 to send the

TERMINATE command described in

Section 4.3.3.3 on page 79.

4.3.2.3 Nodes 3 through 126

Nodes 3 through 126 are used as “read only” nodes and are assigned for use by the

ATTACH command. Although most Protogate protocols allow multiple sessions per

node number, it is easier if your programs assign a separate node number per session.

The Freeway server assigns the next lowest available read node number for each new

connection it receives. Again, your program does not have to follow this scheme. It

would be easier to assign a fixed node number for each ICP port (or service). For exam-

ple, a session to port 0 would always use node 3, port 1 would use node 4, and so on.

4.3.3 DLI Session Commands

The following commands are used to establish and terminate sessions with Protogate

protocols on the ICP. The command codes described here are placed in the command