Fiber-optic star coupler for IEC 60870-5-103 RER 125

Enables various modules to be interconnected over the LON bus to form a communication system

Not active product since 2012

The RER 125 unit functions as an interconnector of devices using the IEC 60870-5-103 protocol.

It provides the power required by all the cards within the unit by integration of a single or double power supply. The supply voltage of the power supply card is either 110...240 VAC/DC or 24...60 VDC. These power supply cards can be used in any combination.

Further, the RER 125 unit contains an I/O module card. This module incorporates two fault relays used for diagnosing the condition of the power supply cards. The external power source required for the power supply cards is wired through this card. The fault relays can be connected to an alarm unit for monitoring the power supplies of the RER 125 unit.

The RER 125 unit provides the mother board connection for the option cards. The mother board contains two internal open collector buses and a power supply line, to which all eight option card slots are attached.


  • Used as interconnector for devices using the IEC 60870-5-103 protocol

Product benefits

  • Enables a large number of device to be connected

Product features

  • 8 slots for option cards (SFIB103)
  • Communication speed 9600/19200 bps

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