What are Fieldbus coupling devices?
Fieldbus coupling equipment (often informally referred to as bricks)

So that the end user does not have to construct and commission junction boxes using conventional terminal blocks. A photo of a Fieldbus coupling device from the Turck brand appears here.
Where fieldbus couplers are used?
For all industrial fieldbus systems, FF or otherwise, coupling devices are highly recommended. These devices not only provide a convenient way to form highly reliable connections between field instruments and the trunk cable, but many of them are equipped with features such as short circuit protection and spur status LED indication.
Installation:
Cables that connect to a coupling device must be fitted with unique plugs that match the coupler sockets. This introduces a bit of a issue when trying to pull such a cable through an electrical conduit: the bulky plug needs either over-sized conduit to accommodate the width of the plug, or after pulling through the conduit it needs the plug to be installed on the cable.
It should be observed that while a correctly protected and grounded FF cable is quite susceptible to interference with radio frequencies, coupling systems may have “fragile places” where radio interference can discover its way into the section.
In any case, it is a good practice to avoid “keying” any portable radio transmitter in the near vicinity of a Fieldbus coupling device.
Uses of fieldbus coupler:
This Fieldbus connecting unit is properly marked as a section guard, as it not only drives couples to the Fieldbus segment’s primary