Reference Guide

ZCOM C I/F Library Routines
Introduction
Chapter 4140
ZLU Definition
The zlu field of a <zaddr_type> parameter specifies the ZLU address. The
checksum field of a <zaddr_type> parameter is a checksum used to verify
the address of the message. All routine calls that specify ‘(with
checksum)’ in the ZLU definition must have both fields defined correctly
for successful processing.
The checksum minimizes the possibility of messages being accidentally
misdirected. The checksum is calculated based on the type and name of
the ZLU, hence the checksum does not change even when the system is
restarted. If the program that opened the ZLU is killed, it may reopen
the same ZLU by referencing it by ZLU name and the same checksum
will be generated. This allows any other message sources to deliver data
to a restarted ZLU without any impact.
The node field of a <zaddr_type> parameter must contain a valid node
number or zero if it is an input parameter. However, if it is a return
parameter, such as in the zopen call, then the node number returned is
the local node as defined in the “configuration file”. Note that specifying
a node number of zero is the same as specifying the local node number. If
a remote node is specified, it must be defined in the Node-Definition
section of the TTGEN configuration file. Refer to the ACC Utilities Guide
for more information about the TTGEN configuration or the ttgen(1) man
page file.