Feature:1. RELAY: Relay is an electrical control device, an electrical appliance that causes a predetermined step change in the controlled quantity in an electrical output circuit when the change in the input quantity (excitation) meets the specified requirements.2. AUTO SWITCH: It has an interactive relationship between the control system (also known as input circuit) and the controlled system (also known as output circuit). Usually used in automated control circuits, it is actually an automatic switch that uses a small current to control the functioning of a large current.3. MULTI FUNCTION: It plays the role of automatic adjustment, safety protecting, switching circuits and so on in the circuit, and it is a very practical accessory.4. COMMUNICATING CHIP: RS232 relay module is equipped with mature and stable 8 bit MCU and RS232 level communicating chip, which adopts RS232 communicating protocol in standard for MODBUS RTU format.5. 3 CHANNEL: This relay module can realize 3 channel input signal detection, 3 channel relay output, which can be used for digital detection or power control occasions.Specification:Item Type: Relay Module Material: PCBPower Supply Voltage: 5-32VCommunicating Protocol: Support Standard For Modbus RTU ProtocolCommunicating Interface: Support RS232 InterfaceCommunicating Baud Rate: 4800 9600 19200, Default 9600bps, Support Power Down SavingOutput Signal: Relay Switch SignalDevice Address: Range 1-255, Default 255, Support Power Down Save.Package List:1 x Relay Module