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4-18 Input / Output MN1921
The CAN channel is opto-isolated. A voltage in the range 12-24V must be applied to pin 5 of
the CAN connector. An internal voltage regulator provides the 5V required for the isolated CAN
circuit. Practical operation of the CAN channel is limited to 500Kbit/s owing to the propagation
delay of the opto-isolators.
The CAN channel must be terminated by a 120Ω resistor connected
between CAN+ and CAN- at both ends of the network and nowhere
else. If the NextMove ST is at the end of the network then ensure
that jumper JP1, located just below the status display, is in position.
This will connect an internal terminating resistor.
A very low error rate over CAN can only be achieved with a suitable
wiring scheme, so the following points should be observed:
H The connection arrangement is normally a multi-point drop. The CAN cables should have
a characteristic impedance of 120Ω and a delay of 5ns/m. Other characteristics depend
upon the length of the cabling:
Cable length
Maximum
theoretical
bit rate
Resistance Conductor
area
0m ~ 300m (0ft ~ 984ft) 500Kbit/s <60mΩ/m 0.34 ~ 0.60mm
2
300m ~ 600m (984ft ~ 1968ft) 100Kbit/s <40mΩ/m 0.50 ~ 0.60mm
2
600m ~ 1000m (1968ft ~ 3280ft) 50Kbit/s <26mΩ/m 0.75 ~ 0.80mm
2
H The 0V 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 ST or
CAN peripheral devices are within the common mode range of the receiver circuitry of
other nodes on the network.
4.6.3.1 CANopen and Baldor CAN
The NextMove ST can communicate with other MintMT controllers over a CANopen network.
Baldor CAN is a proprietary CAN protocol, allowing the NextMove ST to communicate with a
range of Baldor ioNode CAN peripherals.
CANopen is a networking system based on the serial bus CAN. It uses the international CAN
standard ISO 11898 as the basis for communication. The Mint firmware implements a
CANopen protocol, based on the ‘Communication Profile’ CiA DS-301, which supports both
direct access to device parameters and time-critical process data communication. This
provides support for a range of Baldor and third-party devices. The NextMove ST has the
ability to act as the network manager node or as a slave on the CANopen network.
Baldor CAN is also a networking system based on the serial bus CAN. It uses the
international CAN standard ISO 11898 as the basis for communication. Optional MintMT
firmware can be downloaded to implement a proprietary Baldor protocol on CAN bus 2, based
on CAL (the CAN Application Layer). This supports both direct access to device parameters
and time-critical process data communication. Baldor CAN provides support for the full range
of Baldor ioNode CAN peripherals.
The baud rate and node number of the NextMove ST can be set using the BUSBAUD and
NODE keywords.
JP1