Rockwell Automation 2706-MB1 MESSAGEVIEW 421 SOFTWARE MANUAL - Manual (Page 51)

4–3 Planning an Application
Publication 2706-817
Here are the steps needed to create an application:
1. The designer should document the application carefully. This
documentation should include the purpose of the application,
what information the operator will need to make good decisions,
and what choices the operator will have to make. The designer
and operator should discuss this document together before the
application is run.
!
ATTENTION: Documentation is often neglected, but
is very important. The operator can make better
decisions if the designer explains what is going on.
2. The designer creates an application, the basic design unit of
MessageBuilder software. It is designed to be loaded in a specific
type of MessageView terminal, run using a specific type of
controller, and direct a specific operation. It includes:
– messages, with their attributes, triggers, embedded graphics,
and embedded display and entry variables
– configuration parameters for communications port(s) of a
specific MessageView terminal
– global attributes that apply to all messages in the application
– tags, which are named references to data addresses in a
specific logic controller (ASCII Triggering devices use the
tags as memory references)
– function keys and LEDs (MessageView 421F terminals only).
3. The designer associates the application with a project, which is
assigned or created when an application is created. A project can
support more than one application, provided that all of them are
designed for the same type of terminal and the same type of logic
controller. It links the application(s) to:
– the tag database
– the specific devices – the MessageView terminal and the PLC,
SLC or ASCII Triggering device – that the application will
interact with.
4. Values associated with variables are stored in controller memory
addresses, and are referenced by the application via named tags.
The designer usually enters all the tags in the Tag Editor Table
View before creating any messages. Tags may also be edited later
when they are assigned to their variables.
Applications and Projects