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Seeking Advice on MinDIN 8 to USB Converter - Printable Version

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Seeking Advice on MinDIN 8 to USB Converter - Diesel - 08-13-2023

I'm seeking information or recommendations about compatible adapters for listening to COM1 on the IRIS Indigo through USB Serial, as I'm planning to use it for checking any messages that may appear during the initial power-on diagnostics, etc. I've found limited online resources about this and would appreciate any specific knowledge or insights anyone might have.

RE: Seeking Advice on MinDIN 8 to USB Converter - weblacky - 08-14-2023

(08-13-2023, 11:39 PM)Diesel Wrote:  I'm seeking information or recommendations about compatible adapters for listening to COM1 on the IRIS Indigo through USB, as I'm planning to use it for checking any messages that may appear during the initial power-on diagnostics, etc. I've found limited online resources about this and would appreciate any specific knowledge or insights anyone might have.

It's not proprietary, it's RS-422.  So buy a USB to RS422 adapter (page 181-182): http://www.sgistuff.net/hardware/systems/documents/007-9065-050-indigo.pdf

Then cable it to a Mindin-8 with parts from Mouser or digikey.

The Iris Indigo keyboard/mouse port IS proprietary, not the rest.

I don't know much about the difference but I think a "Computer to Device cable" : https://ipc2u.com/articles/knowledge-base/the-main-differences-between-rs-232-rs-422-and-rs-485/

Looks like you need to make a DB9 to MiniDin-8 converter cable.  Use Pinout signal info in indigo manual to creeate a signal match.

Thanks.

RE: Seeking Advice on MinDIN 8 to USB Converter - robespierre - 08-14-2023

The USB-to-RS422 adapters provide a DTE port, and the Indigo has a DTE port. So you would need a null-modem type cable.
The standard cable of that type was called an "ImageWriter II cable". Serial printers also have DTE ports.

RE: Seeking Advice on MinDIN 8 to USB Converter - weblacky - 08-14-2023

(08-14-2023, 12:32 AM)robespierre Wrote:  The USB-to-RS422 adapters provide a DTE port, and the Indigo has a DTE port. So you would need a null-modem type cable.
The standard cable of that type was called an "ImageWriter II cable". Serial printers also have DTE ports.

Can you please track down and post the pinout...I found nothing for NULL modem cabling for a one-to-many RS-422 protocol, that's why I didn't post such a claim myself.  Computer-to-Device cabling on the above site already swaps TX and RX in RS-422 cabling for "computer to device" picture shown..isn't what a cable to dumb terminal would do anyway?  OP asked for serial terminal interface, doesn't the "computer-to-device" cable presented not appear to be that?

Can you please provide a source, I cannot find one single reference to a Null modem cable pinout existing for RS-422, since it's a master-slave (multi-slave capable bus) it doesn't appear to need it.

RE: Seeking Advice on MinDIN 8 to USB Converter - johnnym - 08-14-2023

(08-14-2023, 01:09 AM)weblacky Wrote:  Can you please track down and post the pinout...I found nothing for NULL modem cabling for a one-to-many RS-422 protocol, that's why I didn't post such a claim myself.  Computer-to-Device cabling on the above site already swaps TX and RX in RS-422 cabling for "computer to device" picture shown..isn't what a cable to dumb terminal would do anyway?  OP asked for serial terminal interface, doesn't the "computer-to-device" cable presented not appear to be that?

Can you please provide a source, I cannot find one single reference to a Null modem cable pinout existing for RS-422, since it's a master-slave (multi-slave capable bus) it doesn't appear to need it.

I use null modem cables I originally created for accessing my Power Macs wih Stealth Serial Port. I used the connection scheme as described here:

Code:
Mini DIN-8 (male) | DB-9 (female) | RS-232 Signal
------------------+---------------+--------------
1                 | 8, 6, 1       | CTS, DSR, DCD
2                 | 7             | RTS
3                 | 2             | RXD
4                 | 5             | SGND
5                 | 3             | TXD
6                 | -             | NC
7                 | 4             | DTR
8                 | 5             | SGND

I use these cables to access my Indigo, Indigo²s, Indys and Origin200 (MSC port). I am currently unaware of any hardware configuration inside SGI machines that switch from RS-232 to RS-422. This worked for me out of the box for all machines listed, so it's either detected automatically or it's prefconfigured to RS-232. Or my serial to USB adapters have a play in here.

RE: Seeking Advice on MinDIN 8 to USB Converter - weblacky - 08-14-2023

Taking another look its claims "4D compatible" serial. Which is compatible with both RS-422 & RS-232, which is confusing but both are mentioned. So you're right in that later SGI system manuals for Indy/Indigo2 reference Indigo in their pinout notation.

I guess they are in fact the exact same pin out as a Indy/Indigo2. I don't know why they mention Mac RS – 422 compatibility at all but I guess they're trying to imply that they're tolerant of both voltages.