DDM provides real-time monitoring of the optical module's key parameters, such as temperature, voltage, and optical power. This information is transmitted over the module's I2C bus and can be read using a compatible host device. In. Digital Diagnostics Monitoring (DDM), also known as Digital Optical Monitoring (DOM) or Diagnostic Monitoring Interface (DMI), is a standardized feature defined by SFF-8472 that allows network devices to monitor real-time optical transceiver parameters such as temperature, voltage, transmit power. Modern optical transceivers support standard Digital Diagnostics Monitoring (DDM) functions, which enable real-time monitoring of modules' parameters.