The Instrument Control Unit or ICU is the interface between the spacecraft and the EPD sensors. All EPD sensors are connected to the ICU, which provides them a telecommand and telemetry communication link, time synchronization, processing and power.
The ICU is composed of the Common Data Processing Unit (CDPU) and the Low Voltage Power Supply (LVPS), operating in a cold redundant configuration. Therefore the ICU contains four electronic boards, two for the CDPU (nominal+redundant) and two for the LVPS (nominal+redundant). The LVPS provides power to the CDPU and the sensors.
The ICU boards are packaged in a single box in order to reduce mass and to simplify harnessing and interfaces. This box is mounted inside the spacecraft body.
Sensors have also an interface to receive a pulse per second from the ICU. The pulse per second is generated synchronously with the reception of the SpaceWire time-code that the spacecraft transmits periodically. Sensors, as a response to this pulse, provide synchronized data to the ICU with a 1-second period, except SIS that sends data with a 3-second period. The ICU shares information with MAG, RPW and SWA Solar Orbiter instruments to allow synchronized high data rate burst-mode operations following the on-board identification of predefined triggering events in the EPD data.