Question on SCSI Termination

Lamaman71 · 17 June 2024, 18:01

Hi Folks,

I have A4091 with a ZuluSCSI. I recently connected an external Zip drive, set the ID and Termination. Also switched switch 7 on the A4091 for external devices.

Does the SCSI Zip drive now need to be switched on all the time for the termination to work?

Kin Hell · 17 June 2024, 20:37

Shouldn't need to with Active termination in place & that you have both ends of the SCSI bus terminated correctly.

Have you tried it "off" to answer your own question?

Lamaman71 · 18 June 2024, 01:29

Ive tried both. When the ZIP drive is off - and Ive not tested exhaustively - Ive had a few errors accessing the SD Card on the A4091. Im wondering if the cause might be the lack of termination when the zip drive is off.

Daedalus · 19 June 2024, 09:51

In general powering the drive shouldn't be needed. SCSI hosts provide power for termination. That's not to say of course that there isn't a failure or design flaw involved, or a marginal connection somewhere. I take it the other end of the chain (connected internally) is terminated also?

patrik · 19 June 2024, 10:16

The ZIP drive terminator would need to be configured to source termination power from the SCSI bus for it to work with the ZIP drive unpowered. Should be detailed in the ZIP drive manual. If that is not possible, use a separate external terminator after the ZIP drive, they always source termination power from the bus as they can’t get it anywhere else.

17 June 2024, 18:01	#1
Lamaman71 Registered User Join Date: Sep 2021 Location: Katy, USA Posts: 163	Question on SCSI Termination Hi Folks, I have A4091 with a ZuluSCSI. I recently connected an external Zip drive, set the ID and Termination. Also switched switch 7 on the A4091 for external devices. Does the SCSI Zip drive now need to be switched on all the time for the termination to work?

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17 June 2024, 20:37	#2
Kin Hell 0ld0r Git Join Date: Mar 2009 Location: Cornwall, UK Posts: 1,660	Shouldn't need to with Active termination in place & that you have both ends of the SCSI bus terminated correctly. Have you tried it "off" to answer your own question?

18 June 2024, 01:29	#3
Lamaman71 Registered User Join Date: Sep 2021 Location: Katy, USA Posts: 163	Ive tried both. When the ZIP drive is off - and Ive not tested exhaustively - Ive had a few errors accessing the SD Card on the A4091. Im wondering if the cause might be the lack of termination when the zip drive is off.

19 June 2024, 09:51	#4
Daedalus Registered User Join Date: Jun 2009 Location: Dublin, then Glasgow Posts: 6,381	In general powering the drive shouldn't be needed. SCSI hosts provide power for termination. That's not to say of course that there isn't a failure or design flaw involved, or a marginal connection somewhere. I take it the other end of the chain (connected internally) is terminated also?

19 June 2024, 10:16	#5
patrik Registered User Join Date: Jan 2005 Location: Umeå Age: 43 Posts: 935	The ZIP drive terminator would need to be configured to source termination power from the SCSI bus for it to work with the ZIP drive unpowered. Should be detailed in the ZIP drive manual. If that is not possible, use a separate external terminator after the ZIP drive, they always source termination power from the bus as they can’t get it anywhere else.

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