Chapter 2
Installation
©
National Instruments Corporation
2-5
NI PXI-8214 User Manual
Both ends of the SCSI bus must be terminated. The PXI-8214 default
configuration terminates one end of the SCSI bus. (To change this
configuration, refer to the
Termination Configuration
section.) The other
end of your SCSI bus must be terminated also. Many SCSI devices have
onboard termination that can be enabled, or you can add an external
terminator to the end of the bus. Improper termination can cause
unpredictable bus operation.
Cautions
The PXI 8214 is a 16-bit SCSI interface using active termination that fully
terminates one end of the 16-bit SCSI bus. The user must provide termination for the other
bus end.
You can use 8-bit devices (such as most SCSI CD-ROMs), but you must be careful when
cabling and terminating these devices. If only 8-bit devices reside on the SCSI bus, you can
use the 8-bit termination on those devices as the end termination.
However, if both 8-bit and 16-bit devices are used, end termination must be from either a
16-bit device at the end of the bus or an external 16-bit terminator. Terminating a 16-bit
SCSI bus with an 8-bit device can result in unpredictable bus operation.
Each device must have at least 0.1 m (3.93 in.) of cabling between them.
When connecting more than one device, you must use a daisy-chain
configuration. A star configuration is not allowed.
Figure 2-2.
Single SCSI Device with Independent Termination
PXI 8214
Terminated
Device ID 7
Each cable is at
least 100 cm
SCSI CD-ROM
Device ID 4
Termination of SCSI Bus