The two-wire data bus line may be routed parallel, twisted and/or shielded, depending on EMC requirements. ABB recommends 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 ABB, with part numbers beginning CBL004-5... . The maximum bus length depends on the bit-timing configuration (baud rate). The table opposite shows the approximate maximum bus length (worst-case), 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.
CANopen
The NextMove ESB-2 must have the CANopen firmware loaded to use this protocol
ABB has implemented a CANopen protocol in Mint (based on the ‘Communication Profile’ CiA DS-301) which supports both direct access to device parameters and time-critical process data communication. The NextMove ESB-2 design does not comply with a specific CANopen device profile (DS4xx), although it is able to support and communicate with the following devices:
Any third party digital and analog I/O device that is compliant with the ‘Device Profile for Generic I/O Modules’ (CiA DS-401). Baldor HMI (Human Machine Interface) operator panels, which are based on the ‘Device Profile for Human Machine Interfaces’ (DS403). Other ABB controllers with CANopen support for peer-to-peer access using extensions to the CiA specifications (DS301 and DS302). The functionality and characteristics of all ABB CANopen devices are defined in individual standardized (ASCII format) Electronic Data Sheets (EDS) which can be found on the Mint Motion Toolkit CD (OPT-SW-001), or downloaded from www.abbmotion.com. The configuration and management of a CANopen network must be carried out by a single node acting as the network master. This role can be performed by the NextMove ESB-2 when it is configured to be the Network Manager node (node ID 1), or by a third party CANopen master device. Up to 126 CANopen nodes (node IDs 2 to 127) can be added to the network by a NextMove ESB-2 Manager node using the Mint NODESCAN keyword. If successful, the nodes can then be connected to using the Mint CONNECT keyword. Any network and node related events can then be monitored using the Mint BUS1 event. Note: All CAN related Mint keywords are referenced to either CANopen or Baldor CAN using the ‘bus’ parameter. Although the NextMove ESB-2 has a single physical CAN bus channel that may be used to carry either protocol, Mint distinguishes between the protocols with the ‘bus’ parameter. For CANopen the ‘bus’ parameter must be set to 1. Please refer to the Mint help file for further details on CANopen, Mint keywords and keyword parameters
CAN opto-isolators and power supply
The NextMove ESB-2 CAN channel is opto-isolated, so a voltage in the range 12-24 V must be applied to pin 5 of the CAN connector. From this supply, an internal voltage regulator provides the 5 V at 100 mA required for the isolated CAN circuit. Connection of the supply can be achieved by modifying an existing cable (see Figure 27). However, it is recommended to use adaptor part OPT-CNV001 fitted at the HMI panel (Figure 28). This adaptor provides an RJ45 input to allow standard CAT 5e cable to be used between the HMI panel and the NextMove ESB-2. The adaptor also provides flying lead connections for the application of the CAN power supply. CAN cables supplied by ABB are ‘category 5’ and have a maximum current rating of 1 A, so the maximum number of NextMove ESB-2 units that may be used on one network is limited to ten. Due to the propagation delay of the opto-isolators, the 1 Mbit/s baud rate might not be attainable in some applications.