User guide

Neuron C Programmer’s Guide 117
6
How Devices Communicate Using
Application Messages
This chapter describes the use of application messages,
which can be used in place of or in addition to network
variables. The request/response mechanism, a special use of
application messages, is also described. Other topics
covered include preemption mode, asynchronous and direct
event processing, the use of completion events with
messages and with network variables, and authentication
for messages.
Application messages are used for creating a proprietary
interface (that is, non-interoperable) to a device. The same
mechanism used for application messaging can also be used
to create foreign-frame messages (for proprietary gateways)
and explicitly addressed network variable messages.