PRACTICE PROBLEM SOLUTIONS
1. To control a conveyor system
2. For simple designs
3. A PLC is a computer based controller that uses inputs to monitor a process, and uses outputs to control a process using a program.
4. Less expensive for complex processes, debugging tools, reliable, flexible, easy to expand, etc.
5. A PLC could replace a few relays. In this case the relays might be easier to install and less expensive. To control a more complex system the controller might need timing, counting and other mathematical calculations. In this case a PLC would be a better choice.
6. The ladder logic outputs were modelled on relay logic diagrams. The output in a relay ladder diagram is a relay coil that switches a set of output contacts.
7. off, on
8. Generic: LD A, LD B, OR, ST Y, END; Allen Bradley: SOR, BST, XIO A, NXB, XIO B, BND, OTE Y, EOR, END