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October 29, 2005

T3 Serial Cables

Q. Seeing as how you know about T3 Disk Lights, could you tell me how to use the serial port on a T3 - it looks like a phone connector but seems to need four wires.

A: Well, if you need to know about Sun Serial Ports, the ultimate reference can be found at SunHelp: Serial Port Resources. This wonderful document suggests for the T3:

Sun StorEdge T3 Disk Tray (This information is reprinted from the Sun StorEdge T3 Disk Tray Installation, Operation, and Service Manual.)
Pin  Function

1    Ground

2-3  Reserved

4    Ground

5    RXD

6    TXD

The controller card has an RS-232 serial port connector (RJ11-6). A standard serial cable is used to connect the controller service interface to a dumb terminal or computer serial port with terminal emulation.
Note: The serial port is reserved for special service procedures that can be performed only by qualified, trained service personnel. Do not attempt to perform any procedures through the serial port or you risk damaging the disk tray configuration and data.

In Australia, you cannot buy an RJ11-6 but you can buy RJ12 adaptors at Dick Smith. These are exactly the part you need. Given how fiddly the plugs are, I would use 6 core cable, wire up the RJ12 and an RJ45 at the other end (don't worry about cable order at this point). Then use an RJ45-25pin convertor plug that lets you shift the wires around. Make sure that pin 1 on the RJ12 ends up being pin 1 on the 25 ping serial plug. Pins 5 and 6 should be 3 and 2 respectively.

As for the warning about using it, you should be aware that all the boot messages are sent to that serial port..... if you have a misbehaving T3, a serial cable is the ONLY way to check what is happening. It certainly lets you check the status of the network port and the status of the components as well.

Note that the T3plus is quite different so make sure you actually have a T3 if you want to use this cable.

Posted by Ozguru at October 29, 2005 06:00 AM