We start by setting up I/O descriptions using the Address/Symbol editor.
We select “Add New Record” and enter the address, description, and symbol for the Emergency Stop input and Conveyor Motors 1 and 2 outputs.
Note that we have assigned these I/O to the add-on I/O cards instead of the on-board I/O located on the CPU module.
There are two reasons for this.
- First, if the CPU hardware fails, we do not have to de-terminate I/O wiring to replace the CPU. This saves time and prevents possible short circuits.
- Secondly, the digital outputs of the OW8 card can handle a greater load than the on-board outputs, such as the ones needed for the motor start relays.