European Space Agency

RDIU (Remote Data and Interface Units)


The objective of this project is the development and qualification of a new version of Remote Data and Interface Units (RDIU) enabling to respond to a larger range of telecommunication payloads in a cost effective manner.

The main activity consists of the design, development, manufacture, test and qualification of the BUSTM module, which generates two redundant OBDH buses outside the RDIU interfacing to other payload units.

The achieved improvements are (1) significant reduction of analog telemetries to be acquired by the RDIU, (2) reuse of payload units with RUBI (OBDH) interface qualified and used on SB4000 satellites, (3) simplification of the payload harness, and (4) simplification of payload assembling and integration tests.

In addition the new hardware includes the firmware evolution in order to manage two external OBDH buses and to generate a generic firmware compatible with various RDIU versions.

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Key issues of this project are:

  • DDR documentation including RDIU equipment documentation (for topics related to the BUSTM module, BUSTM module documentation and firmware documentation,

  • BUSTM EM module,

  • Test report of the BUSTM module,

  • RDIU qualification test reports.


The new version of Remote Data and Interface Units (RDIU) will allow quickly to respond to a larger range of telecommunication payloads in a cost effective manner, providing interface to 60 payload units via OBDH-RS485 data bus, including the acquisition of 32 analog and 64 digital telemetry data.


The main functions of the BUSTM board are the provision of two redundant external OBDH-RS485 data buses to interface up to 60 Remote Terminals on the payload, the acquisition of 32 analog (ANA format) and 64 digital (DB format) differential sensors.

The BUSTM board includes two identical Nominal and Redundant electronic functions, named bricks, which operate in cold redundancy. It is thus possible to power independently both the nominal and redundant bricks. These two redundant bricks have no common parts, except the back plane interface connector, and the external interface connectors for ANA/DB inputs, and interface with the same 60 remote terminals and the same 32 ANA, 64 DB external sensors. Each brick is supplied by the CVRDIU board converter of the dedicated RT1553 board, so simultaneously switched ON/OFF.

The main function of the software used by the microcontroller of the RT1553 board (core board of the RDIU) is the treatment of commands received by the RDIU on the 1553 bus before transmitted to the related boards through the internal data bus, and the collection of all internal and the payload units TMs, under platform computer control.


The development activities are:

  • Design, development and documentation of the BUSTM board,

  • Manufacturing and validation tests of the EM,

  • Development of the test equipment for the BUSTM board,

  • Development of a new standard and flexible firmware embedded in the equipment,

  • Qualification of the new RDIU on the PFM model.

Current status

Finished (November 2007).

Status date

Tuesday, February 12, 2008 - 15:38