Terastation Serial console
This page describes the hardware modifications needed to convert the TeraStation UPS serial port to a console port so that you can see the TeraStation's boot messages.
If opening the TeraStation did not void your warranty, this will. Opening the case probably doesn't void your warranty since the manual for the TeraStation gives detailed instructions on how to replace a drive. However, soldering pin-head/jumpers onto the mainboard is clearly not sanctioned as a necessary end-user activity by the manufacturer.
Enabling the console serial port requires some soldering skills, so practice on a dead mainboard first.
If you add a serial console, it is your own decision and I'm not responsible for any damage. These are just tips on what to do, if you are not sure what I'm talking about, don't try it.
As we can see from the hardware page, the CPU offers two serial ports. The first one is used for the system console, but it's not accessible from outside the box. The second one is used to communicate with the XXX microcontroller.
But there actually is a serial port on the back of the box. Officially it is used to communicate with the UPS. If we open the TeraStation, there is a serial port in lower back corner:
Close to it is a Sipex3220EE level shifter to convert the 5v (or 3.3v) TTL-levels to RS232.
If we look closely, we see that the three (actually four) pins of the level shifter are connected to middle pin of the three connectors: JP3 (TxD), JP4 (RxD), JP5 (Vcc).
In order to connect the system console we must first remove the three 0Ω resistor (R437, R440, R441) and move them to (R438, R439, R442). Instead of moving them, we could just remove them and add pin-heads/jumpers to allow simple switching.
In any case the Rx line from the CPU will still not be connected. We also have to bridge R76 to connect it. Do not remove R75, it is a 10kΩ pull-down. If you remove it the input line to the CPU will float and feed random junk to it, not what you want.
If you add pin-heads/jumpers, then you can use them to toggle from serial console (all jumpers to the left, as shown) and UPS support (all to the right). Always put the jumpers all to the left or all to the right. If you don't you might kill the CPU.
J1 can be used to directly access the serial console, but it uses 3.3v TTL levels and you need a separate level shifter. I added some connectors, as I already had a proper level shifter from some other embedded projects. (From memory: Pin1 is Vcc, Pin2 is GND, Pin3 is RxD, Pin4 is TxD, but I'd have to check to be sure.)
With all the jumpers to the left you can now connect your PC to the serial console using a cross-over (null modem) cable. Start your terminal program, configure the serial port to use 57600 8N1, aka:
- Speed: 57600
- Parity: none
- Data Bits: 8
- Stop Bits: 1
- No flow control
If you power on the reassembled TeraStation you can see the boot messages.
The crucial information came from TeraStation �?��?��?��?� - シリアルコンソール�?� SSH.