[Introduction]:ME31-AAAX4220 is a network I/O networking module with 2-way A-type relay output, 2-way analog (0-20mA/4-20mA) input, 4-way dry contact input detection, supports ModbusTCP protocol or ModbusRTU protocol for acquisition and control, and the device can also be used as a simple Modbus gateway (automatically send commands with non-local Modbus addresses through serial ports/network ports).
| No. | Label | Description |
| 1 | TX(LED) | Serial port send data indicator light |
| 2 | RX(LED) | Serial port receiving data indicator light |
| 3 | LINK (LED) | network connection light |
| 4 | NET (LED) | Network data sending and receiving indicator light |
| 5 | PWR (LED) | Power input indicator |
| 6 | DI1 (LED) | Digital channel 1 input indicator |
| 7 | DI2(LED) | Digital channel 2 input indicator |
| 8 | DI3 (LED) | Digital channel 3 input indicator |
| 9 | DI4 (LED) | Digital channel 4 input indicator |
| 10 | DO1 (LED) | The first relay output indicator |
| 11 | DO2(LED) | The second relay output indicator |
| 12 | GND | Negative pole of power input terminal, DC 8V~28V, 5.08mm Phoenix terminal. |
| 13 | VCC | Positive pole of power input terminal, DC 8V~28V, 5.08mm Phoenix terminal. |
| 14 | AI1 | Analog input channel 1, supports 0 to 20mA current input, 5.08mm Phoenix terminal. |
| 15 | GND | Channel 1 analog input ground, DC 8V~28V, 5.08mm Phoenix terminal. |
| 16 | Al2 | Analog input channel 2, supports 0 to 20mA current input, 5.08mm Phoenix terminal. |
| 17 | GND | Channel 2 analog input ground, DC 8V~28v, 5.08mm Phoenix terminal. |
| 18 | NO1 | Relay 1 normally open pin, used with relay 1 common terminal, 5.08mm Phoenix terminal. |
| 19 | COM1 | Common terminal of relay 1, used in conjunction with the normally open pin of relay 1, 5.08mm Phoenix terminal. |
| 20 | NO2 | Relay 2 normally open pin, used with relay 2 common terminal, 5.08mm Phoenix terminal. |
| 21 | COM2 | Common terminal of relay 2, used in conjunction with the normally open pin of relay 2, 5.08mm Phoenix terminal. |
| 22 | Ethernet | Ethernet interface, standard RJ45 interface. |
| 23 | DI4 | Digital input channel 4, supports dry contact access, 5.08mm Phoenix terminal. |
| 24 | DI3 | Digital input channel 3, supports dry contact access, 5.08mm Phoenix terminal. |
| 25 | DI2 | Digital input channel 2, supports dry contact access, 5.08mm Phoenix terminal. |
| 26 | DI1 | Digital input channel 1, supports dry contact access, 5.08mm Phoenix terminal. |
| 27 | GND | Channel 1-4 digital input ground, 5.08mm Phoenix terminal. |
| 28 | 485-A | The A of the serial port is connected to the A interface of the external device, and the 5.08mm Phoenix terminal. |
| 29 | 485-B | The B of the serial port is connected to the B interface of the external device, and the 5.08mm Phoenix terminal. |