With 1 isolated digital input, it can match the 5-24V input level, and the module actively notify the computer when the level changes. The module is easy to operate, and most of the serial port commands only need 1 byte to realize the function. Provide VB host computer program and source code, which makes it easier to realize computer remote control. After each is accepted, the module returns the status of all relays. In addition, the module can also respond to the relay status query from the host computer program. The upper computer program can judge whether each operation is successful through these feedbacks from the module, and improve the accuracy of control. Adopt CH340G chip USB-TTL solution. Control the pull-in and release of 1-way relay through USB serial port , and the controls the delay of 1 ~ 255 seconds. STC15F104W as the main control chip, Weight: 0.28990787453 pounds, Manufacturer: Tuidzljd