Although the IM Gap field of the BCCB data structure allows values as low as 4 µs for gap time (note this corresponds to a dead bus time of 2 µs) the protocol engine requires time to process the messages. The actual minimum time the protocol engine needs before it can send out the next message is greater than 4 µs, and the minimum value depends on the type of message that proceeds the message to be sent.
If the previous message is a broadcast message and therefore has no status response word the protocol engine needs a minimum gap time of 9.7 µs before the message can be sent. If the IM Gap value of the BCCB structure is set to a value below this it will result in a gap time of approximately 9.7 µs.
If the previous message is one that has a status response word from an RT then the protocol engine needs a minimum gap time of approximately 6.0 µs before the message can be sent.
