Innotech Device Network Cabling - Manual (Page 21)

Innotech Device Network Cabling Installation Instructions
© Mass Electronics Pty Ltd 2007 Chapter 2 – Primary Networks Page 21
2-2.3 Earth Connections
The earth connection type on HMIs and converters depends on the typical application of the device.
A potential earth difference between main installations and remote HMIs can cause problems in the
network.
An attempt must be made to eliminate the earth potential differences between the Net comms
and Global comms network cabling. This applies to any soft or floating earth device connected to a
primary network.
The list below indicates the different types of earth connections.
• The GENII VIEWPORT has terminal 3 for the dedicated earth connection. It is used for the soft earth
path of the comms screen terminal
• The MP01 MiniPort has terminal E for the dedicated earth connection. It is used for the soft earth
path of the comms screen terminal
Where either the GENII VIEWPORT or MP01 MiniPort may have the 24V neutral earthed there is no link to the earth
terminal. Therefore a hard earth connection to the earth terminal is still required.
NOTE
• The CONV E should have the 24 V supply earthed on the secondary of the transformer as best
practice. The CONV E has a floating type screen connection
• The CONV USB and the CONV 232 are isolated or floating devices and where they have a soft earth
type comms connector fitted there is no path to earth available at these devices
The following indicates how a network can be practically wired to eliminate earth potential
differences and problems that may occur between the Net and Global networks.
1. When the HMI or converter is mounted at the end of a run, the Global can finish at the last
controller. It is sufficient to run NET only from the last controller to the HMI or converter.
Figure 2-8: End of Run Mounted HMIs or Converters
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