Installation / Preparation for commissioning
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Page 82 of 131 TR - ECE - BA - DGB - 0060 - 05 02/23/2017
4.3.2 Cable definition
Line, e.g. 64-200-021: 2x2x0.25+3x0.14+2x0.5 mm
2
Data+ / Data–
(RS422+ / RS422–)
min. 0,25mm
2
, twisted in pairs and shielded
Clock+ / Clock–
(RS422+ / RS422–)
The maximum cable length depends on the SSI clock frequency and cable quality and
should be conditioned to the following diagram.
Pay attention, that per meter cable with an additional delay-time t
D
(Data+/Data–) of
approx. 6ns must be calculated.
SSI clock frequency [kHz]
A shielded data cable must be used to achieve high electromagnetic interference
stability. The shielding should be connected with low resistance to protective ground
using large shield clips at both ends. Only if the machine ground is heavily
contaminated with interference towards the control cabinet ground the shield should
be grounded in the control cabinet only.
It is also important that the data- and clock-lines are routed separate from power
current carrying cables if at all possible.
The applicable standards and guidelines are to be observed to insure safe and stable
operation!
In particular, the applicable EMC directive and the shielding and grounding guidelines
must be observed!