You should also note that bit I:1/02 is also in a High or True state.

You should now be able to see the current state of each bit associated with input card I:1. When you have the Data Table showing, select the 'Input Table' from the drop down Table list box. Now open the Data Table display by clicking on the Data Table icon located on the toolbar (3rd from right) at the top of the screen. With the door fully closed, what signal level would you expect to see at the limit switch inputs I:1/03 and I:1/04? To confirm your assessment of the current limit switch states, place the PLC into the RUN mode which will initiate scanning.

Run your mouse over each switch, and you should see a tool-tip text box appear, which denotes that the selected switch is wired using a set of Normally Open contacts. When the door is in the closed position, both limit switches are in their activated state (Not Normal). Take the time to familiarize yourself with the components used in the Door system, and take particular note of the current state of the limit switches.

1 LogixPro Door Simulation Student Exercise Utilizing Relay Logic The ProSim-II Door Simulation From the Simulations Menu at the top of the screen, select the Door Simulation.