Adding a serial port to a QNAP TS-251D

I am using a QNAP TS-251D NAS. Because I would like to switch from QTS to Alpine Linux I though it would be useful to enable the serial port.

The TS-251D has a built-in serial port that is already enabled and only needs to be connected. For that you need a number of parts:

• JST 4-pin connector. I selected Adafruit accessoires JST PH 2mm 4-pins - 3950
• TTL to Serial port level converter. I am using JZK 4 PCs 3V-5V RS232 to TTL serial port module.

In addition, I am using a 3D printed bracket to hold the serial port.

Examinig the QTS environment you can see that there is indeed a /dev/ttyS0 device (a serial port) and it is enabled in the Kernel command line with:

console=ttyS0,115200n8

Simmilarly you can find in the /etc/inittab a line:

ttyS0::respawn:/sbin/getty -L ttyS0 115200 vt100

So there is a serial port available and being used for debugging.

To make it visible to the outside, you only need to connect to JST1

Pins from left to right.

1. GND
2. RX
3. VCC
4. TX

For the bracket to hold the serial port I printed this 3D Model.

Place the Serial module on the 3D printed bracket.

And mount it on the case: