FBUS-HSE/H1 Linking Device-- unprotected surface mount boards ?

[tgb-beck]

With the HSE Linking device, I noticed that the circuit board opposite the heatsink vent is exposed to the environment. 

This circuit board appears to be an uncoated surface mount (fine pitch) board.

Presumably, this would be mounted facing the "ceiling" of the industrial wiring cabinet, since you would want the processor heat to escape from the top. 

Unfortunately, this means that any dust and junk in the atmosphere collects on the surface of the SMT board.  It wouldn't take much in the

way of fine metal fragments to cause shorts.

So is the board coated ?  Is there an "approved" way of covering the vent with an air filter to protect the device ?

[fieldbus]

Our products meet pollution degree 2 requirements. Adding a filter will not lower pollution degree. You can install the FBUS one of NI's enclosures or an equivalent enclosure to reduce exposure to dust. Enclosure used should have UL or TUV certification (approval) for Ingress Protection (e.g., IP54 min).