Configuration Guidelines

The system software cannot perform all actions in all states. The host must operate in accordance with the following restrictions of each state:

• If the system software is in any state other than Active, only the Core Message Set is available. The Core Message Set is a small subset of the API messages. Use the Core Message Set only for downloading system software and for tracking the status of the Matrix Controller.

• The system software can use hardware resources only if they are reported in the Card Status Report message.

• Before the host can configure the Excel platform, the Active system software must send a Poll message with the Ready For Configuration status bit set.

• The host monitors the Poll messages status bit, "Download this Matrix", and initiates a download if it is set. The system software cannot leave the Boot state until it has received a valid download.

• The host monitors all the status bits in the Poll message for indications of failure which prevents the Excel platform from operating with defective hardware.

• Only one Matrix Controller transitions to the Active state. The host can either allow the Excel platform to select which Matrix Controller becomes Active, or it can send a Become Active message to the Matrix Controller that it wants to address as the active Matrix Controller.

In a non-redundant system, the system software runs in exactly the same states and follows the same rules. The only difference is that the single Matrix Controller always runs in the active state.