Connecting a serial console to QNAP TS-21x devices

If you want to connect a serial console to a QNAP TS-21x device, you'll need a 3.3V TTL to RS-232 level shifter. The serial connector is of type JST PHR-4 and the wires need to be crimped into a JST SPH-002T-P0.5S connector pin before it can be fitted inside the JST PHR-4 connector. The layout is as follows from right (1) to left (4):

TX (red)
VCC (green)
RX (black)
GND (white)

On the TS-219, the serial port can be accesses fairly easily through the hard drive slot at the front. On the TS-219P, the serial connector is labelled CN3 and is very hard to reach via the SATA slot. On newer TS-219P+ devices (revision 1.3 of the board), the connector is labelled CN1.

Once you have connected your serial console, you can use a terminal emulation program to connect to U-Boot, the boot loader used by this device. You have to connect with 115200 baud and set the parameters to 8N1 (8 data bits, no parity, 1 stop bit). U-Boot on a separate page about U-Boot.