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4.
BUS ISOLATION AND TERMINATION RESISTORS
If the communication bus is accessible for the user, it shall be double insulated. As far as in general
the accessibility of the bus to users will depend on each single installation, safety isolation has been
implemented in the Lumiplus physical bus layer. Moreover, for safety purposes, it is recommended to
ensure that other devices sharing this bus also implements this insulation.
Additionally, the use of bus insulated devices not only enhances the security level, furthermore
increases the equipment reliability, larger immunity to electromagnetic interference, longer life,
higher reliability, more stability over the range of temperatures.
Whenever single or multiple devices are connected sharing a bus physical connection, it is
recommended to use terminating resistors at the ends of the bus, even more when use large cable
length or high speed data rates. The terminating resistor is used to prevent an RF signal from being
reflected back from the end, causing interference.
The terminating resistor must be in both ends of
the bus, connected in parallel (as shown in the image below). A typical value of this resistance is
120Ω, 0.5W. The value of the resistor must be the same in both ends. The terminating resistors are
the resistors
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of the image below
Image 2 Terminating Resistors
Summary of Contents for 57434
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