Phoenix Contact 2701399 NLC-START-01 NANOLINE STARTER KIT NPN-TRANSISTOR 2701399 Ficha De Dados

Códigos do produto

2701399

nanoNavigator

2-8

PHOENIX CONTACT

2373_en_B

2.4

Flow Charting Primer

This flow charting primer is for new users that have no experience with flow chart

programming. It provides a brief introduction to flow chart programming concepts

specifically as they relate to programming the nanoLC using nanoNavigator. For those

already familiar with flow chart programming, skip to the next section, “Designing a Control

2.4.1

Introduction and History

Although flow charting predates 1947, it was formally introduced at that time as a way to

clearly communicate computer program designs. This ‘new method’ of using labeled blocks

to show the order of a process became so successful that the American National Standards

Institute (ANSI) developed standards for flow charts in the early 1970s.

After that, flow charts became a standard for displaying all types of procedures (product

launches, quality practices, troubleshooting documentation, etc.), as well as a very reliable

means for monitoring and controlling electro-mechanical devices through PC-based

programs. This is because people from all walks of life could easily understand a graphical

path with instructions of what to do along the way.

Flow charts are step-by-step procedures written using blocks (actions and decisions) and

flow lines. Flow lines indicate direction of movement (or path) from block-to-block. Flow

charts are simple to write, easy to understand, and programming knowledge isn’t required

to write a flow chart!

In control programs, flow chart paths return to a desired point in the path – to repeat the

process. Generally, it takes multiple flow charts to create a control project, although it is

conceivable that simple projects may require only one flow chart.

Control projects are a set of flow charts that control a process. Control projects run on a

computer (like the nanoLC or a PC). The computer runs a program that scans through user-

designed flow charts in a desired sequence. To do this, projects need to perform the

following tasks:

–

Control the process by monitoring inputs

–

Manipulate outputs as required

–

Display status information (normal conditions)

–

Display diagnostic information (abnormal conditions)

–

Recover from an error

nanoLC solves all flow charts in a project on each scan cycle (for more information on scan