Item Type: Relay Board Module Control Terminal: 19-Wire interface, all interfaces have wiring terminals, which is convenient for users to wire 1. DC+: External DC Power Supply Positive (5V, 12V and 24V Modules Available) 2. DC-: External DC Power Supply Negative 3. XM: Common Terminal of Photoelectric Isolation Chip If high level control is adopted: this signal should be connected to the negative pole of the power supply of the user control board If low level control is used: this signal should be connected to the positive pole of the user control board power supply 4. X1-X16: Relay Control Interface, If XM is connected to the negative pole of the power supply: when this port is high (relative to XM), the corresponding relay is closed If XM is connected to the positive pole of the power supply: when this port is low (relative to XM), the corresponding relay is closed Relay Output Terminal: 48-Wire interface, all interfaces have wiring terminals, which is convenient for users to connect 1. NO1--NO16: The relay normally open interface, the relay is suspended before being closed, and it is short-connected to COM after being closed. 2. COM1--COM16: Relay Common Interface 3. NC1--NC16: Normally closed interface of the relay, the relay is short-connected with COM before the pull-in, and it is suspended after the pull-in.