Seagate ST336807FC Cheetah 10K.7 FC Product Manual - Page 84

The - Enable Bypass Port A - EN BYP Port A and - Enable Bypass Port B - EN BYP Port B signals

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9.5.8 Active LED Out The Active LED Out signal is driven by the drive as indicated in Table 33. Table 33: Active LED Out conditions Normal command activity Spun down and no activity Spun down and activity (command executing) Spun up and no activity Spun up and activity (command executing) Spinning up or down Format in progress, each cylinder change LED status Slow blink (20% on and 80% off a 2 sec cycle) On On Off Blinks steadily (50% on and 50% off) Toggles on/off The Active LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the proper +5 volt supply through an appropriate current limiting resistor. The LED and the current limiting resistor are external to the drive. 9.5.9 Enable port bypass signals The - Enable Bypass Port A (- EN BYP Port A) and - Enable Bypass Port B (- EN BYP Port B) signals control the port bypass circuits (PBC) located external to the disc drive. The PBC allows a loop to remain functional in the event of a drive failure or removal. When these signals are active, low, the PBC bypasses the drive on the associated port. When an Enable Bypass signal is active, the corresponding Port Bypass LED signal in connector J1 is driven low by the disc drive. A pull down resistor, 1K, located with the PBC should be used to insure the bypass is enabled if the disc drive is not installed. The Enable Bypass signal is active under failing conditions within the drive, on detection of the Loop Port Bypass primitive sequence, or on removal of the drive. In the bypass state the drive continues to receive on the inbound fibre. Enable Bypass may be deactivated by detection of a Loop Port Enable primitive sequence if the drive has completed self-test and a hardware failure is not present. Failure modes detected by the disc drive that will enable bypass include: • Transmitter/receiver wrap test failure • Loss of receive clock • Loss of transmission clock • Drive interface hardware error 72 Cheetah 10K.7 FC Product Manual, Rev. D

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72
Cheetah 10K.7 FC Product Manual, Rev. D
9.5.8
Active LED Out
The Active LED Out signal is driven by the drive as indicated in Table 33.
The Active LED Out signal is designed to pull down the cathode of an LED. The anode is attached to the
proper +5 volt supply through an appropriate current limiting resistor. The LED and the current limiting resistor
are external to the drive.
9.5.9
Enable port bypass signals
The – Enable Bypass Port A (– EN BYP Port A) and – Enable Bypass Port B (– EN BYP Port B) signals control
the port bypass circuits (PBC) located external to the disc drive. The PBC allows a loop to remain functional in
the event of a drive failure or removal. When these signals are active, low, the PBC bypasses the drive on the
associated port. When an Enable Bypass signal is active, the corresponding Port Bypass LED signal in con-
nector J1 is driven low by the disc drive. A pull down resistor, 1K, located with the PBC should be used to
insure the bypass is enabled if the disc drive is not installed.
The Enable Bypass signal is active under failing conditions within the drive, on detection of the Loop Port
Bypass primitive sequence, or on removal of the drive. In the bypass state the drive continues to receive on the
inbound fibre. Enable Bypass may be deactivated by detection of a Loop Port Enable primitive sequence if the
drive has completed self-test and a hardware failure is not present.
Failure modes detected by the disc drive that will enable bypass include:
•
Transmitter/receiver wrap test failure
•
Loss of receive clock
•
Loss of transmission clock
•
Drive interface hardware error
Table 33:
Active LED Out conditions
Normal command activity
LED status
Spun down and no activity
Slow blink (20% on and 80% off a 2 sec cycle)
Spun down and activity (command executing)
On
Spun up and no activity
On
Spun up and activity (command executing)
Off
Spinning up or down
Blinks steadily (50% on and 50% off)
Format in progress, each cylinder change
Toggles on/off