ABB Advant Controller 450 User Manual

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This section is not intended to be a formal guide to application programming but rather a
collection of suggestions and ideas for program design and structuring. The following are
general rules for program design:
• Structure the application program (see below).
• Write programs that are as readily understandable as possible.
• Avoid “smart” programming unless absolutely necessary to achieve the necessary
performance.
• Prepare a draft PC diagram in which the required function is built up with the help of PC
elements.
• Use the largest elements possible.
• Use the most powerful elements possible.
• Use the principles of typical solutions (type circuits).
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When structuring the application program, you must satisfy these three requirements:
• Structuring in accordance with the structure of the plant and the process.
• Structuring in accordance with execution time.
• Function orientation from the typical solution aspect.
The structure elements primarily used are PCPGM, CONTRM and FUNCM. SEQ and STEP
are also used with sequential control.
The elements PCPGM, CONTRM and SEQ are execution-controlling. You can activate and
deactivate these elements from outside—do this when high performance is required. The
elements are only activated when execution of the subsidiary program (-section) is necessary.
Place the execution control in its own module with a short cycle time. Note, however, that there
may be occasions such as at start, stop and emergencies when you must run all programs (-parts)
simultaneously. If there are such occasions, they determine how hard the controller can be
utilized.
Use the following as rules of thumb when structuring:
• Do not place the whole application in just one PC program.
• It is preferable that you place independent parts of the application program which have no
data exchange or a limited data exchange in different PC programs.
• A control module (CONTRM) delimits a function to which a special cycle time is applied.
• A function module (FUNCM) delimits a function consisting of several control modules or
divides a control module into subfunctions.
• Use more than three levels with structure elements only in exceptional cases.
• Use BLOCK elements to close part of a control module when reducing the load on the
controller.

ABB Advant Controller 450 Specifications

General

Brand	ABB
Model	Advant Controller 450
Category	Controller
Language	English