Can Wiring - Baldor NextMove ESB-2 Installation Manual

4.5.2 CAN wiring

A very low error bit rate over CAN can only be achieved with a suitable wiring scheme, so the
following points should be observed:
The two-wire data bus line may be routed parallel, twisted and/or shielded, depending on

EMC requirements. Baldor recommend a twisted pair cable with the shield/screen
connected to the connector backshell, in order to reduce RF emissions and provide
immunity to conducted interference.
The bus must be terminated at both ends only (not at intermediate

points) with resistors of a nominal value of 120 Ω. This is to reduce
reflections of the electrical signals on the bus, which helps a node to
interpret the bus voltage levels correctly. If the NextMove ESB-2 is at
the end of the network then ensure that jumper JP1, located just
behind the status display, is in position. This will connect an internal
terminating resistor. To access the jumper it will be necessary to
remove the top cover from the NextMove ESB-2. Before removing
the top cover be sure to discharge static electricity from your body
and clothing by touching a grounded metal surface. Alternatively,
wear an earth strap while handling the unit.
All cables and connectors should have a nominal impedance of 120 Ω. Cables should

have a length related resistance of 70 mΩ/m and a nominal line delay of 5 ns/m. A range
of suitable CAN cables are available from Baldor, with catalog numbers beginning
CBL004-5... .
The maximum bus length depends on the bit-timing

configuration (baud rate). The table opposite shows the
approximate
assuming 5 ns/m propagation delay and a total effective
device internal in-out delay of 210 ns at 1 Mbit/s, 300 ns
at 500 - 250 Kbit/s, 450 ns at 125 Kbit/s and 1.5 ms at
50 - 10 Kbit/s.
(1)
CAN baud rate not supported on Baldor CAN.
(2)
For bus lengths greater than about 1000 m,
bridge or repeater devices may be needed.
The compromise between bus length and CAN baud rate must be determined for each

application. The CAN baud rate can be set using the BUSBAUD keyword. It is essential
that all nodes on the network are configured to run at the same baud rate.
The wiring topology of a CAN network should be as close as possible to a single line/bus

structure. However, stub lines are allowed provided they are kept to a minimum (<0.3 m
at 1 Mbit/s).
The 0 V connection of all of the nodes on the network must be tied together through the

CAN cabling. This ensures that the CAN signal levels transmitted by NextMove ESB-2 or
CAN peripheral devices are within the common mode range of the receiver circuitry of
other nodes on the network.
Servo Systems Co. • 115 Main Road • P.O. Box 97 • Montville, NJ,
MN1957
07045-0097 • (973) 335-1007 • Toll Free: (800) 922-1103
maximum bus length
Fax: (973) 335-1661 • www.servosystems.com
CAN
Baud Rate
(worst-case),
1 Mbit/s
500 Kbit/s
250 Kbit/s
125 Kbit/s
100 Kbit/s
50 Kbit/s
20 Kbit/s
10 Kbit/s
Input / Output 4-23
www.baldormotion.com
JP1
Maximum
BUS Length
25 m
100 m
250 m
500 m
(1)
600 m
1000 m
(2)
2500 m
(2)
5000 m