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How do I expand the M340 architecture to include 4 backplanes?

Published date: 21 August 2019

I need more IO than one rack can handle, How do I expand the M340 architecture to include 4 backplanes?

Product Line:
Modicon M340
Modicon M580

EcoStruxure Control Expert
Unity Pro


In order to expand an M340 configuration to include 4 backplanes, you will need 4 BMXXBE1000 modules.
The M340 CPU can have a maximum of 3 expansion racks for a total of 4 racks, including the Main Rack, which is refered to as Rack 0.
You will need to add the 3 expansion racks to your Control Expert project by going into the PLC Bus configuration and Double-clicking on the small square icon uder the Main Rack that is connected by a line to the other square Icon with the 0 in it. This will open the New Device configuration where you will select the new rack.
This will need to be done for each additional rack. You can then add the desired modules to the configuration. Keep in mind, the BMXXBE1000 modules are not selecting in this configuration, it is transparent to the CPU configuration.

To set up the BMXXBE1000 modules, you will need to set up the DIP switches on the side of the module in Binary for the corresponding Rack number it will be placed in, Switch 1 is the Most significant Bit, while Switch 3 is Least significant.

Lastly, you will need to use BMX XBC or TSX CBY Cab;es to interconnect the rack extender modules and use TSX TLYEX to terminate the unused ends.

Refer to the attached document for further expanation and diagrams.

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