5.4.1 Termination of the CANopen line
To accomplish safe communication over the CANopen line, termination of the cable is very important (see the drawing
below). The applied cable must be of the type twisted pair with screen, e.g. 50 mm2, e.g. from Solar. The
maximum length at Baud rate 125 kbit/s is 500 m, and 250 m at Baud rate 250 kbit/s.
NOTE The cable screen must never be connected to earth.
NOTE In case the communication is interrupted because of noise, connect the cable screen to terminal 5 and also 8, if
dual CAN is used, on all instruments in the loop.
NOTE It is recommended that the two cable screens for CAN 1 and CAN 2 are not connected.
If the environment is very noisy (electrical noise), the below-mentioned arrangement can be used for enhanced EMC
characteristics.
Rt/2 = 60 Ohm, Cg = 10…100nF
The capacitor should be connected to a “quiet” ground level, e.g. the screen of the used cable, that is then connected to
the GND input on each illuminator.
NOTE
The capacitor must never be connected to any other ground, e.g. the earth or the hull of the ship.
The example below shows how a CAN line different from a single line structure can be arranged. In the example a star
topology with three branches is shown. To accommodate such a topology, the multiple termination concepts may be
considered. Note the value of the used termination resistors.
Installation and commissioning guide 4189350024O EN
Page 32 of 39
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