Question about serial ports on old mac G3

Summary: How do I configure AppleTalk over a serial port on a G3/MacOS8.6?



Disclaimer: This may be incorrect, or may make no sense, because I don't know anything much about these systems!

We have an older PowerPC Mac system that controls a piece of scientific equipment (which I'll call 'the machine'). Apparently it uses appletalk via an inbuilt round 'modem' port on the mac (which I assume is a serial port).

We're trying to encourage a second system to be our 'backup' in case of problems with the original system. It's a slightly less old G3 running MacOS 8.6. It has a Keyspan SXPro serial card with four serial ports, identical to the 'modem' port on the PowerPC Mac.

The problem is that we can't get the G3 to talk to the machine through these ports. I think what we need is an Appletalk connection via the serial port.

On the (non-communicating) G3, the Appletalk setting called "connect via" only allow us to choose "remote only" or "ethernet", whereas the (communicating) PowerPC system allows us to choose both of those, as well as "modem port", which is currently selected and working.

... any ideas?

It has been a very long time since Appletalk so I may miss something.

You need these connectors

PHONENET PLUS FARALLON 2 PORT APPLETALK 8 PIN CONNECTOR | eBay

large lot Apple appletalk localtak equipment lot | eBay

they hook together with telephone cable with the 4 pin ends. I remember the end of the lines (they connect in a line - daisy chain style) and I seem to remember they had to be terminated in the two extreme ends with a plug with a resistor. I could not find a link on ebay.

Does the machine have any other network connectors other than Appletalk? Is it possible the machine receives only to the port and cannot be a network device? Is there a USB or printer connector like on older PC style printers? There are USB to Appletalk and Ethernet to Applenet adapters out there.

On getting Appletalk to work, I seem to remember once it "sees" a network, Appletalk will appear allowing you to select it. Once selected I remember restarting the machine and it was ready. Appletalk was in the Printer window but not sure. Been like 20 years now... Pictures would help.

You may need a driver for that Keyspan card to make it show up in connect via. If thats a minidin connector you can use old apple printer cables. You also have to turn on Appletalk in its control panel and you may have to set up the device like a printer in the chooser. There are ethernet to appletalk adapters. You also may have to choose between modem port or printer port with the Keyspan driver. Look on the old powermac for a Keyspan driver in the Extensions folder. copy it and move it to the G3..