The EM1202EV-RS and "-TM" devices have "12V"-to-3.3V switching regulator onboard. The power is supplied through the power jack. The power jack of the EM1202EV accepts "small" power connectors with 3.5mm diameter. Use APR-P0011, APR-P0012, or APR-P0013 power adapter supplied by Tibbo or similar adapter with 12V nominal output voltage. Adapter current rating should be at least 500mA. On the power jack, the ground is "on the outside", as shown on the figure below.
Stabilized 3.3V power used by the EM1202EV-RS and "-TM" is also available on pin 12 of the TTL interface connector. This can be used to provide power to an attached serial device.
The EM1202EV-TS board does not have "12V"-to-3.3V regulator at all. 3.3V power required for board operation must be supplied by the external device through pin 12 of the TTL interface connector.