1.3 PROGRAM DESIGN METHODS
• NOTE: these are structured design methods - although many of the design activities are obvious, by following the same steps, others can understand what you have done, and others will get similar results when they solve a similar problem. This is a simple start, and we will advance to significant design techniques later.
1.3.1 Process Sequence Bits
• A simple process will typically go through clear steps. Each step should follow the other, and when done the process goes back to the beginning.
• The general steps to this method are,
1. Understand the process
2. Write the steps of operation and give each a number
3. For each step assign a bit
4. Write the ladder logic to turn the bits on/off as the process moves through its states.
• Consider the problem below.
1.3.2 Timing Diagrams
• By writing a timing diagram, the sequence of steps in a program can be obvious.
• The general steps to this method are,
1. Understand the process
2. Identify the outputs that are time dependant
3. For each step assign a timer
4. Write the ladder logic to turn the outputs on/off as time progresses.
• Consider the problem below.
