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Entry type: FAQ Entry ID: 109760536, Entry date: 12/19/2018

Switching the 3VA2 ON of OFF via communication networks using EFB300 and MO320

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How can the molded case circuit breaker 3VA2 be switched via communication using EFB300 and MO320?



The SEO520 is equipped with two spring packages (for very fast switch actions) and a communication interface. This interface enables the SEO520 to switch the braker without any additional external wiring, it just needs the power supply.
Another option to remotely switch the 3VA2 is to use a combination of the standard motor operator MO320 and a digital output module on a network (like ET200S on PROFIBUS). Disadvantage is always the missing logical link between COMx00 and this additional module.
Suggested proposal: The external function box EFB300 offers 4 digital outputs. Two of them can be used to operate the MO320 when they are connected as shown in the drawing attached in this FAQ.


  • 3VA2 with ETU 5 or 8-series and firmware release 4.2 or higher (check with product versions Exy noted at the front of the ETU, depending on In and type of ETU):

  • COM060 with firmware release 4.2 or higher (Download available FW-update from SIOS)
  • COM800/100 mit Firmware 4.2 or higher (Download available FW-Spdate from SIOS)
  • EFB300
  • MO320 (DC24 ...60 V, AC110 ... 230 V or DC110 ... 250 V)


The outputs DO2 and DO3 of the EFB300 are used to control the inputs of the MO320; only the relay outputs can be used. The parts for MAN and AUT in the drawing are optional.
To switch the breaker via MO320 the outputs must be controlled like shown below:

The settings of the EFB300 must be configured in order to use the outputs to control the breaker. Please configure the digital output 2 and 3 as shown in the screenshot from powerconfig 3.11 below (powerconfig is available for download in the SIOS portal).

Control the outputs via Ethernet (Modbus TCP)

To control the outputs, the command 0x06 in Modbus Register EFB_MMB_OUT_REMOTE (0x9CCB) has to be used.

As know, for Modbus, the address has to be decreased by 1.
Example: EFB_MMB_OUT_REMOTE turns from 0x9CCB to 0x9CCA.

Control the outputs via PROFIBUS or PROFINET

The intended bits to control the breaker in the cyclic channel can only be used with SEO520.

To control the EFB300 outputs an acyclic service has to be used. The content of a data block must be written using data set DS48. This is done in the S7 with the following call.

This example shows how the call works. The content of data block DB88 with the length of 6 byte is written to the PROFIBUS/PROFINET of COM800/COM100 using DS48 and the corresponding ID (identification number given in hardware config).

The content of DB88 (where 88 is just an example) must be:


REG_ADDR must be filled with 0x9CCA (Modbus Register).
BREAKER_ADDR is the address of the breaker on the 3VA-line. Only addresses 1 to 8 are allowed. 
REG_CNT must be filled with 0x01
CONTROL_VALUE contains the data which is going to be sent to EFB_MMB_OUT_REMOTE.

It is also possible to control multiple breakers at the same time with just one acyclic telegram. To do so, the DB88 has to be extended with the exact same principles for every single breaker and the WRREC has to be adjusted.

  FAQ_switch_MO320_via_EFB300.pdf (83,8 KB)

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