The interface board feature an on board Multi channel TDL2A-433-9 OEM serial modem, MAX232 RS232 driver, 9 way D connector, 5V voltage regulator and SMA RF connector, hence requires just a Voltage supply to power up and operate without any additional interface circuitry. The TDL2A modules would be soldered directly on to the interface board for better grounding and to improve RF performance. The helical antenna and the SMA connector shown are optional. User could also use a two pin terminal block instead to mount a 1/4 whip antenna made of piece of wire or metal rod