First, ensure that the power supply to the WSA PC-220 is stable and within the specified range. Check all connections to ensure they are secure and properly terminated. Next, verify the programming settings in the panel, particularly those related to communication protocols and device addressing. If everything seems correct, try resetting the panel to its default settings and reprogramming it from scratch. If the issue persists, it might indicate a hardware problem with the panel itself, and you may need to contact technical support for further assistance.