1. If the LED subtitle printer (display screen) control card uses an RS232 serial port and you are using a laptop, you generally need to use a USB to RS232 cable for auxiliary connection. Some systems cannot directly recognize the driver for the USB to RS232 cable, so you need to install the driver from the CD that came with the USB to RS232 cable to display "Successfully established communication with the controller". If your control card supplier uses the same software for multiple models, you also need to select the matching model.
2. If the LED subtitle printer (display screen) control card uses a network port and the software does not have an automatic IP address selection function, you need to set it manually.
3. Check if the cable is intact. Note: We have encountered similar situations many times. Telephone and remote computer assistance methods have been tried without success, and even having the customer replace the cable didn't solve the problem. Finally, when we went to check, we found that the customer was using a handmade cable from a small market stall. Replacing it with the cable we brought immediately resolved the connection. A normal set of cables costs no more than 20 yuan.
4. It's generally not a card problem, because manufacturers conduct multiple testing processes such as aging and power-on checks after production.
5. Check if the card and screen cables are connected backwards, and if the power cord is connected incorrectly. Some power supplies have mismatched indicator labels and wiring terminals; be sure to check carefully, as this is often overlooked when busy.
6. If it's a desktop computer, check if the serial port is oxidized, causing poor contact.
