If installing a system with two doors (both with readers for entry and exit), how many Reader Expanders are required?

Two. Each Reader Expander has two reader ports onboard.

One. With reader multiplexing, a single Reader Expander can support two doors with entry and exit readers.

None. The Controller supports reader multiplexing, which allows two doors with entry and exit readers to be controlled onboard.

One. The Controller has two reader ports onboard so a reader expander is required for the other two readers.