Weidmuller GPRS Alarm Unit - Manual (Page 76)

Hardware
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5.2 Installation notes
Make sure that at least 35 mm of space is left above the module.
A space of 35 mm must be provided beneath the module for routing of
the cables for the interfaces and for the power supply.
5.2.1 Functional earthing
For functional earthing, connect the "Functional earthing" terminal on
the housing of the IE-GPRS-I/O to the equipotential bonding of the
control cabinet.
The connection "Functional earth" serves for purely operational
functions (modem function).
Make sure that the cross-section of the interconnecting line does not
exceed 4 mm
2 .