Baud Rate and Bus Length
bit rate max cable length (in m)
1 MBit/s 25
800 kBit/s 50
500 kBit/s 100
250 kBit/s 250
125 kBit/s 500
50 kBit/s 1000
(Table from CiA DS 301 4.02 page 20) CiA 303 Part 1: Cabling and connector pin assignment has recommendations for connectors and cables used in CANopen systems.

CAN cable types
See can-wiki.info for CAN cable types and more.

CAN Termination
Add CAN termination resistors 120 Ω at both end of CAN bus. The DMA-20 has included a termination resitor with 1 kΩ, it is only for laboratory test without correct CAN bus topology.