Chapter 3 PLC System Configuration & Settings Method 2 Right-click the blank in the system configuration area and click Add from the context menu, then double-click on the selected redundant expansion backplane. The new redundant expansion backplane is placed underneath the selected backplane. Right-click the left side of the selected backplane graphic, choose Add from the context menu and double-click on the redundant expansion backplane (rack) to add. The new backplane is placed underneath the selected backplane. 3-143