An Arbitrated Loop has the following states:
Monitoring | Each port acts as a repeater while listening for further instructions. | |
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Arbitration | The port requests to own the loop. | |
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Open | The port wins arbitration and connects to another device. | |
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Closed | The port relinquishes control of the loop and the loop is in the process of returning | |
to a monitoring state. | ||
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A node can be “hot plugged” where it is inserted or removed from the loop. When hot plugged, the loop loses “sync” and must “reinitialize”. The loop will be able to recover any lost communications during the hot plugging. Typically, a backplane may have a “bypass” circuit. See Figure 6. When enabled, the bypass circuit will remove the device from the loop while keeping the loop connected. The loop will remain operational while the device is connected, performs its POSTs, and becomes ready.
Figure 6. Typical Backplane Bypass Circuit
56 | ZeusIOPS |
