National Instruments 781639-01 CAN Interface Module

The National Instruments 781639-01 CAN Interface Module is an advanced, high-speed Controller Area Network (CAN) Flexible Data Rate (FD) interface, ideal for developing applications with the NI-XNET driver. This module belongs to the model series NI-9862. It is suitable for rapid control prototyping, automated control, bus monitoring, hardware-in-the-loop simulation, and real-time, high-speed manipulation of hundreds of CAN frames and signals. It enables low-level FPGA control and embedded monitoring within the NI CompactRIO chassis, as well as smooth interaction with other data gathering activities within the NI CompactDAQ hardware platform.

This 781639-01 module has an ISO 11898-compatible NXP TJA1041AT High-Speed CAN transceiver that can handle baud rates of up to 1 Mbps. The Bosch DCAN CAN controller supports both 11-bit and 29-bit identifiers and is compatible with CAN 2.0B. Communication between the system's single CAN port and other modules is dependable and free from interference.

This part can handle CAN_H and CAN_L bus line voltages between -27 and +40 VDC and offers a maximum baud rate of 1Mbps. They may supply voltages ranging from +9 to +30 VDC. When in active mode, it draws a maximum of 1 W of power from the chassis and may dissipate up to 1.25 W of heat at 70 °C.

Safety and isolation are paramount in the 781639-01. The port-to-COM voltage ranges from -27 V DC to +40 V DC, adhering to Measurement Category I standards. The external power supply (Vsup) must be between +9 V DC and +30 V DC. For isolation, the port-to-earth ground can handle a continuous voltage of 60 V DC and withstand 500 V RMS, as verified by a 5-second dielectric withstand test.

The 781639-01 supports a CAN bus configuration where 2 or more CAN nodes are cabled together. The CAN_H and CAN_L pins of every node connect to the main CAN bus cable via a short connection known as a stub. This transmission line must be terminated at both ends to prevent communication errors caused by signal reflections. Only the nodes at the far ends of the cable should have termination resistors.