Chapter 1. Product Description
EK–SMCPR–UG. A01
387404-001
1–13
1.2.3.2 Controlling the Internal SCSI Bus
The I/O module controls the internal SCSI bus in the following manner:
•
Isolates the internal SCSI bus from the external SCSI bus.
•
Provides single-ended SCSI bus termination.
•
Disconnects the internal SCSI bus from the external SCSI bus when the EMU so
directs.
•
Distributes TERMPOWER (+5 V dc) to the internal SCSI bus.
•
Turns ON the green internal TERMPOWER LED (see Figure 1-9) when the internal
TERMPOWER is present.
•
Turns OFF the green internal TERMPOWER LED (see Figure 1-9) when there is an
internal TERMPOWER overcurrent condition.
1.2.3.3 Controlling the External SCSI Bus
The I/O module controls the external SCSI bus in the following manner:
•
Provides single-ended SCSI bus termination.
•
Distributes TERMPOWER (+5 V dc) to the external SCSI bus.
•
Turns ON the green external TERMPOWER LED (see Figure 1-9) when the external
TERMPOWER is present.
•
Turns OFF the green external TERMPOWER LED(see Figure 1-9) when there is an
external TERMPOWER overcurrent condition.
•
Automatically disables the external bus termination when a cable is connected to the
right hand VHDCI connector.
1.2.3.4 Controlling the Fault Bus
The I/O module controls the fault bus operation in the following manner:
•
Provides a fault bus driver for improved signal transmission.
•
Distributes the FAULT_CLK and FAULT_DATA signals from the master enclosure
to the expansion enclosures.
•
Distributes the SHELF_OK and SWAP_L signals from the expansion enclosures to
the master enclosure.
1.2.3.5 “Warm Swapping” I/O Modules and Cables
You can replace either the I/O module or a cable when the associated SCSI bus is
quiesced (no data transfers occurring) – a warm swap. This enables you to correct
problems affecting only one bus without disrupting data transfers on the other five buses.
