Understanding how the PLC will scan and update your program is critical in programming and troubleshooting your system. Typically a PLC will solve your logic from left to right, top to bottom. The status of the memory from the previous rung, are available for the next rung to use. We will look at a few examples to determine how the PLC will solve logic to illustrate the above program scanning. Keep on Reading!
The program control instructions will allow us to specify what parts of the logic get solved and when this happens. This will control how the PLC will scan and solve your logic in your program. Keep on Reading!
Compare and math instructions in the Click PLC will allow you to do a number of things. We will use the compare instructions to turn on bits which will indicate production shifts. Using the math instruction we will convert the number of units made to a weight. Keep on Reading!
We will look at a PLC programming example of delaying the start of 7 motors. Each motor will be on a switch that the operator can select at any time. The motor outputs should have a 5 second delay between the outputs coming on.
This question originally came from PLCTalk.net. An original solution to the problem came from Peter Steinhoff. His solution is what we will be presenting. It is simple and straight forward.