If an initiator detects the release of the BSY signal by the target at any other time, the target is indicating an error condition to the initiator. The target may perform this transition to the BUS FREE phase independent of the state of the ATN signal. The initiator shall manage this condition as an unsuccessful I/O process termination. The target terminates the I/O process by clearing all pending data and status information for the affected nexus. The target may optionally prepare sense data that may be retrieved by a REQUEST SENSE command.
ARBITRATION PhaseThe ARBITRATION phase allows one SCSI device to gain control of the SCSI so that it can initiate or resume an I/O process.
The procedure for an SCSI device to obtain control of the SCSI bus is as follows:
a)The SCSI device shall first wait for the BUS FREE phase to occur. The BUS FREE phase detected whenever both the BSY and SEL signals are simultaneously and continuously false for a minimum of a bus settle delay.
b)The SCSI device shall wait a minimum of a bus free after detection of the BUS FREE phase (i.e. after the BSY and SEL signals are both false for a bus settle delay) before driving any signal
c)3)Following the bus free delay in Step(b), the SCSI device may arbitrate for the SCSI bus by asserting both the BSY signal and its own SCSI ID, however the SCSI device shall not arbitrate (i.e. assert the BSY signal and its SCSI ID) if more than a bus settle delay has passed since the BUS FREE phase was last observed.
M3099GX/GH OEM Manual |