Board / Slot Keying
Keying a board is used to allow or disallow board styles from being plugged into certain slots. A card which is keyed to a particular slot will only plug into that slot, or any other slot which accepts that key. Keying the card and chassis forces users to install cards into a particular slot or particular order. A system board keyed the same way as slot one, but not keyed to any other slot forces the installation of that board into slot one and no other.
There are three main ways a board and chassis may be keyed. The most popular way to key a system is to add a key to the bottom of the board face plate, and than key the bottom face of the card cage within the chassis. The second most popular way to key a card is to key the rear board connectors on the card and than key the connectors on the back plane to accept the card. A third way to key a system is to apply form fitting keying systems around both the board and backplane connectors. This last method is normally used only after the system is designed with out a formal keyed system is left out, but found to be required.
Birtcher {Conduction Cooled Keying}
How To Specify a Equipment Chassis; Index page
