How to ensure uninterrupted operation of I/O module under voltage drops?

To prevent I/O modules from malfunctioning during mains voltage dips or short-term interruptions, both power supply design and software logic must be addressed. The power supply section should have a wide input voltage range and include large-capacity energy storage capacitors, such as electrolytic capacitors, at the inputs to maintain short-term power supply during voltage dips. Use a switching power supply with a holding function or add backup supercapacitor/battery modules. For the internal digital circuits of the module, add large local capacitors to the power supply of core chips such as the CPU and FPGA, and monitor their power supply voltage.

When the voltage falls below a threshold, issue an early warning and enter an orderly sleep or data saving state. For digital outputs, they should be designed to enter a safe state in case of power abnormalities; for example, relay outputs should be designed to disconnect upon power failure. In software, implement watchdog and power monitoring functions. Once a power abnormality is detected, immediately save critical data and lock the output. The communication protocol should include timeout and reconnection mechanisms. During testing, perform voltage dip and interruption tests according to IEC 61000-4-11/34 standards to verify whether the module malfunctions or loses data during the test and subsequent recovery process.