It is necessary to terminate the CAN bus network with external termination resistors. The resistors are 120 Ohm, 0.25W minimum, metal film or similar type. They should be placed between CAN_H and CAN_L terminals at both ends of the network. Networks with improper termination will not function.
It is also necessary to use a 120 Ohm resistor, 0.25W minimum, metal film or similar type on the CAN side of the Axiomatic USB-CAN converter when flashing new embedded firmware into the Axiomatic controller over the CAN bus.