My SCSI Terminal Server isn't functioning, what things can I check?

Solution:

Check overall bus length. It could be that adding our unit extended the bus to the point where some noise that had always been at a tolerable level no longer is.  The general rule of thumb for single-ended SCSI is: the shorter the cable, the more reliable it is.

Check cable routing.  Make sure the cables go directly from one unit to the next and are not any longer than they have to be. Make sure our internal termination is removed if we are not at the end of the bus.

Make sure all SCSI connections are secure. Sometimes the little clips do not always snap in place unless you wiggle the cable a little.

Termination:
The rule with terminating SCSI connections is that there should be one termination point (terminating device) at each end of the bus. Keep in mind that one end of the bus will be internal to the system if any internal devices are connected to the same host adapter (controller card) as some external devices.

Current models of the SCSI Terminal Server products with a termination switch on the back use Active Termination. The leftmost switch in the four position dip switch bank (numbered 1) is the termination switch. On older units which have a rotary switch for setting the SCSI ID, the internal termination is in the form of socketed resister packs much like the ones used on hard drives. Since use of these require opening the cabinet, most users choose to use standard external terminators and simply plug them into us, which works fine.

If you think you might be having problems with our internal termination, when we are terminating the bus, try removing/disabling our internal termination and using "active" external termination instead. Also, make sure there is only one external termination point on the bus. There could be local termination accidentally left present on another external device such as a disk or tape drive inside an external expansion cabinet.

On newer units with internal termination, The LED just to the left of the four position dip switch is the termination LED. It is only on when termination is enabled AND termination power is OK. If the LED is off and termination is enabled, it indicates a problem with termination power. If the LED is off and termination is disabled, nothing is indicated.

"Fast-SCSI" compatibility:
Our units are 100% compatible with Fast-SCSI host adapters. What some people don't realize, is that transfer rates are negotiated individually for each unit on the bus, depending on both the Target and Initiator's abilities... or more importantly... what they have in common. Mainly, it is important to understand that a slow device should not affect the transfer rates of faster devices on the same bus. If it does, it can only be due to host adapter software limitations, overall SCSI bus length, or SCSI cable or connection problems.

Wide SCSI or "SCSI-3" 68pin connections:
All our units are standard SCSI-2 using the standard "Micro-D" 50 pin connector. They are compatible with wide SCSI controller cards, but you must get a "Wide to Narrow SCSI" or "68 to 50 pin SCSI" adapter cable for connection. Make sure the cable has what is called either "Partial Termination" or "9-wire Termination", so the unused bus signals are properly terminated in the adapter cable. Without this termination, any wide devices on this bus (including internal devices, as they are on the same bus) may start to fail.