5190/5194 Modular Tape Subsystem Manual

Introduction to the Modular Tape Subsystem
5190/5194 Modular Tape Subsystem Manual—426878-002
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Back-End Board (3216 Controller)
Each 3216 tape controller supports one or two drive CRUs. Figure 1-6 shows the 3216
logic board and BIC.
Back-End Board (3216 Controller)
The back-end board (BEB) translates fiber-optic signals from the 3216 controller into
SCSI commands and information for the cartridge tape drive. A cage-like sheet-metal
enclosure houses the BEB and plugs into a SCSI port on the back of the drive CRU.
The BEB enclosure is visible only when the hinged door on the rear of the module (the
rear bezel door) is lowered. For an illustration of a BEB, see Figure 3-13 on page 3-25.
One BEB can serve one or two drive CRUs. If a module contains two drive CRUs, a
daisy-chain cable links the SCSI port on the rear of the first drive CRU to a port on the
rear of the second drive CRU.
The BEB contains four light-emitting diodes (LEDs). Two LEDs are external (easily
viewed at the back of the BEB cage) and two smaller LEDs are mounted internally on
the circuit board of the BEB. The internal LEDs are used by trained service providers.
You do not need to use the internal LEDs to troubleshoot the BEB.
All BEB LEDs are visible if the hinged door on the rear of the module is lowered or
removed. For a description of the BEB LEDs, see Replacing a BEB on page 6-2. For
BEB problem-solving using these LEDs, see Troubleshooting a BEB on page 6-2.
Fiber-Optic Cable
A duplex fiber-optic cable connects the 3216 BIC to the BEB at the rear of the tape
drive module. Cable lengths can range from 10 meters (33 feet, the default length) to
2 kilometers (1.2 miles). Part numbers for fiber-optic cables are listed in Appendix A,
Part Numbers.
Figure 1-6. 3216 Logic Board and Fiber-Optic BIC
3216 Logic Board 3216 BIC
Red Fault LED
Green Power-On LED
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