G&L MMC-A2, Hardware Manual

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CE and EMC Guidelines
162 MMC Hardware Manual G & L Motion Control Inc.
There is now a provision for shield termination to the CPU modules
for peer-to-peer communication. Shielded cable must be used to
reduce emissions.
Inside a control cabinet, the practice of connecting the shields of
shielded cables at the modules should be continued. For an example
of a shielded cable entering/leaving the cabinet see
Figure 11-3 on
page 162 .
Figure 11-3: Connecting Shielded Cable
The two different methods of terminating shields are used to
accommodate two different immunity requirements. Immunity
required inside an enclosure is considered lower because cables are
typically less than 3 meters in length and/or can be separated from
each other and from noise sources.
Immunity required external to an enclosure is considered higher
because the user may have less control over the noise environment.
Low level signal cables that can be external to an enclosure and
AC/DC digital I/O cables have been tested at a 2 KV level for
electrical fast transients (EFTs). Low level signals that can be less
than 3 meters in length or can be separated from noise sources are
tested at a 1 KV level.
MMC
Module
External
Device
Cabinet
Enclosure