A very brief trouble shooting guide for Small Computer System Interface (SCSI) adapters:

• Make sure you are using the latest BIOS from your motherboard manufacturer. Some have had problems with their PCI bus slots not working properly
• Check to be sure that all SCSI devices attached to the bus powered on.
• Make sure all SCSI cables and power cables properly connected. Try removing and reseating all the connectors to be sure.
• Check that the host adapter and each device on each SCSI bus channel have a unique SCSI ID setting.
• Make sure the SCSI bus is terminated properly. Remember there should only be two terminators on the bus, one on each end. All other termination should be removed or disabled.
• If your system BIOS setup has settings for controlling PCI bus configuration, make sure the PCI slot containing the SCSI adapter is configured for an available interrupt. If your system is Plug and Play, use the Windows Device Manager to check and possibly change the resource configuration.
• Make sure the host adapter is installed in a PCI slot that supports bus mastering. Check your motherboard documentation and try moving the SCSI host adapter to a different PCI slot.

Some additional tips:

• Start by adding one device at a time. Rather than plug numerous peripherals into a single card all at once, start with the host adapter. Then install one device, making sure everything works before moving on to the next.
• Keep good documentation. When you add a Device, write down the SCSI ID address, any other switch and jumper settings, such as SCSI Parity, Terminator power and Delayed or Remote Start. For the host adapter, record the BIOS addresses, Interrupt, DMA channel and I/O Port addresses used by the adapter and any other jumper or configuration settings, such as termination, that might be important to know later.
• Use proper termination. Each end of the bus must be terminated, preferably with active or Forced Perfect,FPT terminators. If you are using any Fast SCSI-2 device, you must use active terminators rather than the cheaper passive types. If you have only internal or external devices on the bus, the host adapter and last device on the chain should be terminated. If you have external and internal devices on the chain, you generally will terminate the first and last of these devices but not the SCSI host adapter, which is in the middle of the bus.
• Use high-quality shielded SCSI cables. Make sure that your cable connectors match your devices.

The SCSI ID setting is very simple. Up to 7 SCSI devices can be used on a single narrow SCSI bus or up to 15 devices on a wide SCSI bus. Each device must have its own unique SCSI ID address. There are 8 or 16 addresses respectively and the host adapters are factory set to ID7 or 15, which is the highest priority ID.

SCSI termination is required at both ends of the bus, there are no exceptions. If the host adapter is at one end of the bus it must have termination enabled. If the host adapter is in the middle of the bus, and if both internal and external bus links are present, the host adapter must have termination disabled and the devices at each end of the bus must have terminators installed.

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