Can't detect Compaq DLT 35/70Gb external drive

[Tony Cassell]

I have a DEC Qlogic SCSI card that is identical to a card working on another PC. I am connecting a Compaq DLT 35/70Gb external drive to the card and when I scan the SCSI bus the tape drive is not connected. The scsi cable and terminator work on another tape drive OK. The SCSI card can see an external drive array ok. The SCSI card is set to SCSI ID 7. I have tried the tape on ID 4, 5 and 6. How do I determine if the tape drive is working correctly?

[Marino Meloni_1]

there is two scsi standard for the electrical level of the communication, and both are not compatible:

you can have SE (Single Ended) or HVD (High Voltage Differential) also called Differential.

you should have all the components of the same scsi bus with the same interface in order to communicate, even if the connectors are the same, the hba, the terminator and the drive should all be or SE or differentials

marino

[Tony Cassell]

Mario,

Thanks for sending me along the right path. The card is SE, the cable is SE, the terminator however, is differential. I am hoping that's the problem, as I have an identical tape drive running on an identical SCSI card in an identical machine.

[Tony Cassell]

The tape drive couldn't be seen because the drive and SCSI card were SE and the terminator was LVD

[Tony Cassell]

conflicting types of SCSI devices on the same bus. SE vs LVD.