PCMCIA-CAN

For PCMCIA-CAN cards, the physical layer is implemented inside the cable.

The three types of physical layers available for PCMCIA-CAN cards are:

• High-Speed
• Low-Speed/Fault-Tolerant
• Single Wire

The High-Speed and Low-Speed/Fault Tolerant cables are powered internally through an onboard DC-DC converter. The Single Wire cables must be powered externally, through the CAN bus.

PCMCIA-CAN High-Speed Cables

The PCMCIA-CAN High-Speed physical layer is powered internally (from the card through a DC-DC converter), and is optically isolated up to 500 V_DC(withstand, 2s max) channel-to-bus. This isolation protects the NI CAN hardware and the PC it is installed in from being damaged by high-voltage spikes on the CAN bus.

Transceiver

PCMCIA-CAN High-Speed hardware uses the Philips TJA1041 High-Speed CAN transceiver. The TJA1041 is fully compatible with the ISO 11898 standard and supports baud rates up to 1 Mbps. This device also supports advanced power management through a low-power sleep mode. This feature is provided as the Transceiver Mode attribute of the Frame API and the Interface Transceiver Mode property of the Channel API. For detailed TJA1041 specifications, refer to the Philips TJA1041 data sheet.

Bus Power Requirements

Because the High-Speed physical layer is completely powered internally, there is no need to supply bus power. The V- signal serves as the reference ground for the isolated signals. Refer to PCMCIA Connector Pinout for information about how to connect signals to a High-Speed CAN interface.

PCMCIA-CAN Low-Speed/Fault-Tolerant Cables

The PCMCIA-CAN/LS cable physical layer is powered internally (from the card) through a DC-DC converter, and is optically isolated up to 500 V_DC(withstand, 2s max) channel-to-bus. This isolation protects the NI CAN hardware and the PC it is installed in from being damaged by high-voltage spikes on the CAN bus.

Transceiver

PCMCIA-CAN Low-Speed/Fault-Tolerant hardware uses the Philips TJA1054A Low-Speed/Fault-Tolerant transceiver. The TJA1054A supports baud rates up to 125 kbps. The transceiver can detect and automatically recover from the following CAN bus failures:

• CAN_H wire interrupted
• CAN_L wire interrupted
• CAN_H short-circuited to battery
• CAN_L short-circuited to battery
• CAN_H short-circuited to VCC
• CAN_L short-circuited to VCC
• CAN_H short-circuited to ground
• CAN_L short-circuited to ground
• CAN_H and CAN_L mutually short-circuited

The TJA1054A supports advanced power management through a low-power sleep mode. This feature is provided as the Transceiver Mode attribute of the Frame API and the Interface Transceiver Mode property of the Channel API. For detailed specifications about the TJA1054A, refer to the Philips TJA1054 data sheet.

Bus Power Requirements

Because the PCMCIA-CAN/LS cable is completely powered internally, there is no need to supply bus power. The V- signal serves as the reference ground for the isolated signals. Refer to PCMCIA Connector Pinout for information about how to connect signals to a Low-Speed/Fault-Tolerant CAN interface.

PCMCIA-CAN Single Wire Cables

The PCMCIA-CAN Single Wire physical layer is powered externally from the CAN bus. The physical layer is optically isolated up to 500 V_DC(withstand, 2s max) channel-to-bus. This isolation protects the NI CAN hardware and the PC in which it is installed from being damaged by high-voltage spikes on the CAN bus.

Transceiver

PCMCIA-CAN Single Wire hardware uses the Philips AU5790 Single Wire CAN transceiver. The AU5790 supports baud rates up to 33.3 kbps in normal transmission mode and 83.3 kbps in High-Speed transmission mode. The achievable baud rate is primarily a function of the network characteristics (termination and number of nodes on the bus), and assumes bus loading as per SAE J2411. Each Single Wire CAN port has a local bus load resistance of 9.09 kΩ between the CAN_H and RTH pins of the transceiver to provide protection against the loss of ground. The AU5790 also supports advanced power management through low-power sleep and wake-up modes. For detailed AU5790 specifications, refer to the Philips AU5790 data sheet.

Bus Power Requirements

The Single Wire physical layer requires external bus power to provide the signal levels necessary to fully use all AU5790 operating modes. You must supply power on the CAN V+ signal. The power supply should be a DC power supply with an output of 8 to 18 V, as specified in the following table. A power supply of 12 VDC is recommended. You should take these requirements into account when determining requirements of the bus power supply for the system.

Synchronization

The PCMCIA-CAN synchronization cable provides the ability to synchronize a Series 2 PCMCIA-CAN card with other National Instruments hardware or external devices. The synchronization cable provides a flexible interconnect scheme for sharing timing and triggering signals in a system. For example, PCMCIA-CAN synchronization is specifically designed to integrate well with National Instruments E Series DAQCard hardware. Timing and triggering signals can be shared by wiring the synchronization cable signals to the appropriate terminals on a DAQ terminal block.

The functionality of the PCMCIA-CAN synchronization cable is very similar to the RTSI bus for PCI hardware, with a few limitations:

• Four general-purpose I/O trigger lines, as opposed to seven for RTSI
• TRIG7_CLK clock line is an input-only signal that can receive a master timebase; the PCMCIA-CAN card cannot drive a timebase onto TRIG7_CLK

The following figure shows the PCMCIA-CAN synchronization signal interconnect architecture for NI PCMCIA-CAN hardware.

PCMCIA-CAN Synchronization Signal Interconnect Architecture for NI PCMCIA-CAN Hardware

The following table shows the function of each trigger line and its corresponding wire color.

To improve the signal integrity of the trigger lines, all GND wires should be connected to digital logic ground of the system. Unused trigger lines may also be grounded. Refer to PCMCIA-CAN Specifications for detailed DC operating characteristics.