Canopen Terminal Block; Electrical Installation; Cable Types; Network Limitations - Lenze SMVector Reference Manual

3.2 CANopen Terminal Block
Table 2 identifies the terminals and describes the function of each. Table 2 also provides an
illustration of the 5-pole 5mm CANopen connector.
Terminal Description
1 CAN_GND: CAN earth ground
2 CAN_L: CAN low
3
4 CAN_H: CAN high
5
Protection against contact
• All terminals have basic isolation (single insulating distance)
• Protection against contact can only be ensured by additional measures (i.e. double insulation)
3.3 Electrical Installation
3.3.1 Cable Types
Due to the high data rates used on CANopen networks it is paramount that correctly specified
quality cable is used. The use of low quality cable will result in excess signal attenuation and
data loss.
3.3.2 Network Limitations
There are several limiting factors that must be taken into consideration when designing a
CANopen network, however, here is a simple checklist:
• CANopen networks are limited to a maximum of 127 nodes.
• Only 32 nodes may be connected on a single network segment.
• A network may be built up from one or several segments with the use of network repeaters.
• Maximum total network length is governed by the data rate used. Refer to Table 3.
• Minimum of 1 meter of cable between nodes.
• Use fibre optic segments to:
− Extend networks beyond normal cable limitations.
− Overcome different ground potential problems.
− Overcome very high electromagnetic interference.
• Spurs or T connections while sometimes useful reduce the network quality, therefore is
strongly advised not to uses spurs as extreme care must be taken during network design
phase so as to avoid problems.
CMVCAN01B
Installation
Table 2: CANopen Terminals
Important
For reliable communication make sure
terminal CAN_GND is connected to CAN
network GND/common. If only two wires are
used (CAN_H and CAN_L) in the network,
connect CAN_GND to chassis/earth ground.
If controller is located at either end of the
network, a terminating resistor (120ohm
typical) should be connected across CAN_L
and CAN_H
6
Connector
5
3 4
1 2