Normally, the DS1206 is powered through its power jack.
The power jack of the DS1206 accepts "small" power connectors with 3.5mm diameter. Use APR-P0011, APR-P0012, or APR-P0013 power adaptor supplied by Tibbo or similar adaptor with 12V nominal output voltage. Adaptor current rating should be at least 500mA. On the power jack, the ground is "on the outside", as shown on the figure below.
Alternatively, the DS1206 can be powered through a pin 9 of the DB9M (RS232) connector. Two internal diodes combine power jack and pin 9 inputs into a single line, which goes to the internal regulator of the DS1206.
The pin 9 of the RS232 port can also be used to provide "12V" power to an attached serial device. Many small serial devices, such as barcode scanners, accept power on pin 9 of their DB9 connectors.
"12V" actually means "input power on the power jack", which is not necessarily stabilized. The power line of the jack passes through a software-controlled switch and is then connected to pin 9 of the RS232 port through a Schottky diode (shown on the diagram below). Therefore, the voltage on pin 9 is close to the input voltage on the power jack. Also, the maximum current an attached serial device can source depends on the maximum output power of the power adaptor (power supply) plugged into the power jack (minus the power consumed by the DS1206 itself).
Tibbo serial-over-IP application supplied with the DS1206 has a dedicated "PS" ("Power on pin 9") setting to control the power switch. To turn the power switch on from within your Tibbo BASIC/C application, enable (configure as output) line PL_IO_NUM8_PWROUT and then set this line to HIGH. Additional programming information can be found in TIDE, TiOS, Tibbo BASIC, and Tibbo C Manual (see i.o object and DS1206 platform documentation).
If you want to use pin 9 of the DB9M connector to power an attached serial device, then you must power the DS1206 itself through the power jack. We know you understand this, but we still had to mention it.