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WVME-DM2 Installation and Configuration Notes
June 25, 1998
BWI
887D Main Street
Monroe, CT 06468
800-419-0294
FAX 203-261-5061
www.bwi.com
!! NOTICE !!
When inserting the disk module into a VME card cage, only apply pressure to the ejector
handles, or if necessary, at the very base of the front panel where it is attached to the
circuit board. Applying pressure to the top of the front panel could cause damage to the
module.
1. Module Power
The WVME-DM2 may obtain power from the VME bus, via the P2 paddle board, or both. Only
one pin on the VME bus backplane carries +12 volts. This provides insufficient current capacity
to meet the startup current requirements for many disk drives. The P2 paddle board has a power
connector which supplies additional power through the user defined pins. Four additional pins
are used for +12 volts, +5 volts, and ground, and two pins are used for -12 volts (NOTE: -12 volts
is not used on the WVME-DM2, but is used on other BWI disk modules).
The P2 paddle board power connections may be used in addition to, or instead of, the VME
power connections. To isolate the WVME-DM2 from the VME bus power supply, it is necessary
to cut W1 and W2 on the circuit board. These jumpers are located near the back edge of the
board between the P1 and P2 connectors. The ground connection between the WVME-DM2 and
the VME bus cannot be broken. If the WVME-DM2 is isolated from the VME bus power supply, a
limited hot swap capability is available by switching the disk module power separately from the
VME bus power. If the module power is shut off, the disk module may be removed without
shutting down the VME bus system. NOTE that it is necessary to insure that the VME bus
system software can handle the disk drive being powered down and then restarting for this
scheme to be effective.
The P2 paddle board supplied with the WVME-DM2 includes the mating connector for the power
connector, with pigtail leads to be connected to the user's system. The color code for the leads
is:
Red
Orange
Black
+5 volts
+12 volts
ground
2. System Configuration
The WVME-DM2 may be attached to the SCSI bus using either the front panel connector, the P2
connector, or both, allowing the module to be used at the end or in the middle of a SCSI chain. If
the WVME-DM2 module is used at the end of a SCSI chain, the appropriate terminators should
be enabled. If the SCSI bus is connected via the P2 connector, the on-board terminators near
the front panel connector should be enabled. If the SCSI bus is connected via the front panel
connector, the terminators near the P2 connector should be enabled. See the section below for
information on configuring the on-board terminators. If the WVME-DM2 module is in the center of
the SCSI chain, both the front panel and the P2 connectors should be used to connect to the
SCSI bus, so that the SCSI bus runs through the module. The WVME-DM2 module has been
specifically designed to meet the SCSI specification for stub lengths (max. 1 1/2") when
configured this way. The onboard terminators should be disabled in this case.
3. Terminator Configuration
The WVME-DM2 module pr ovides two sets of SCSI terminators, one set near the P2 connector
and one set near the front panel connector. The P2 terminator is enabled by inserting resistor
packs in the sockets for RP1 and RP2, and configured with Jumpers K1, K2, and K3. The front
panel terminator is enabled by inserting resistor packs in the sockets for RP3 and RP4, and
configured with jumpers K4, K5, and K6. The resistor packs are 10-pin SIPs containing nine 110
ohm resistors with pin 1 common.
If only the front panel connector is used for the SCSI bus, the terminator near the P2 connector
should be enabled. If only the P2 connector is used for the SCSI bus, the terminator near the
front panel should be enabled. If the module is used in pass-through mode and both connectors
are connected to the SCSI bus, neither terminator should be enabled. Note that an external
terminator may be connected to the front panel connector to allow the occasional connection of
peripherals such as tape drives without reconfiguring the module.
The on-board terminators may be configured as standard active terminators, or may be
configured to provide Forced Perfect termination (FPT) on the three critical SCSI timing signal,
Request, Acknowledge, and Select. To configure the terminators for standard active termination,
position the jumpers on the appropriate jumper blocks (K1, K2, and K3 for the terminator near the
P2 connector, K4, K5, and K6 for the terminator near the front panel connector) on pins 1 - 2 of
each jumper. To enable FPT, position the jumpers on pins 2 - 3 of the appropriate jumpers. Pin
1 of each jumper is to the left side of the board when the board is viewed from the front.
To disable termination, remove the appropriate resistor packs, and either configure the jumpers
for active termination, or remove them entirely.
The WVME-DM2 module should never be used with both on-board terminators enabled. Also,
any terminators included on installed drives should be disabled.
4. Front Panel Indicators
The green LED indicates that terminator power is available on the SCSI bus. The module may
have red or yellow LEDs to indicate drive activity.
5. Selecting SCSI ID
Each device connected to the SCSI bus must be assigned an ID number. The SCSI ID may be
set to any value from 0 to 7. There should be onlyone device with each ID on the bus. Note that
an ID number must be assigned to the host computer as well as the drives. Typically, the host
computer is either ID 0 or ID 7, depending on the operating system used.
The SCSI ID for each drive is set with a 16-position rotary switch onthe front panel. Positions 0 7 set the SCSI ID correspondingly. Themost significant bit of the switch is usually ignored, so
that positions 8 - 15 of the switch duplicate positions 0 - 7. On some modules, the fourth bit may
be used to select special drive options, such as delayed motor start.