IRIS Net UCC 1, Owner'S Manual

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The pin-assignment of CAN-bus connectors is shown in figure 8.
Fig. 8: CAN BUS IN / OUT connector pin-assignment
6.2 The CAN-Bus Standard
Developed in the 1980’s, the CAN-bus norm had been established in the 1990’s by the International
Standardization Organization (ISO) as a worldwide standard. Since then, CAN has become very popular
especially in automotive and industrial applications. CAN is cared for and further developed by the CiA
(CAN in Automation User Organization), an association of 300 well-known companies engaged in different
areas.
The CAN-Bus employs the so-called „Bus-Topology” as network topology; i.e. all participants on the bus are
connected via one single two-wire line (Twisted-Pair-cable, with or without shielding), which, at its ends has
to be terminated using 120 Ω bus termination plugs. Each appliance on the bus can communicate with any
other unit without restriction. Up to 100 network devices can be connected on a single CAN-Bus.
Because the CAN-interfaces of all EVI Audio appliances is galvanically isolated from the rest of the circuitry,
network cabling also carries a common ground (CAN_GND), which guarantees that all CAN-interfaces in
the network are connected to the same ground potential. The ISOLATED / GROUNDED switch in the UCC1
offers the possibility for switching the CAN-Ground (CAN_GND) to circuitry ground potential. Normally, one
UCC1’s switch should be set to its GROUNDED-position while all other UCC1s in the network should be
set to ISOLATED.
Fig. 9: Bus-topology of the CAN-bus
The CAN-bus allows using different data rates. The actual data rate is indirect proportional to the bus
length. “Smaller” networks with short bus lengths permit higher baud rates of up to 500 kbaud. The baud
rate needs to be reduced (minimum 10 kbaud) in networks with extensive bus length. The following table
shows the relation between baud rate and bus length:
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