Campbell Scientific SDM-CAN Datalogger to CANbus Interface - Manual (Page 19)

SDM-CAN Datalogger-to-CANbus Interface
TABLE 2-3. CIA CAN Connector Pin Connections
Pin Function
1 Reserved, NOT INTERNALLY CONNECTED.
2 CAN Low.
3 CAN Ground.
4 Reserved, NOT INTERNALLY CONNECTED.
5 CAN Shield.
6 CAN Ground.
7 CAN High.
8 Reserved, NOT INTERNALLY CONNECTED.
9 CAN +5volts. Input or output (see text).
If the SDM-CAN hardware is configured (in either isolated or non-isolated
mode) with the DC-DC converter ON, then Pin 9 of the 9 pin ‘D’ connector
will provide +5V +/-10% at up to 40mA to any external device. If isolation is
enabled and the DC-DC converter is set to OFF then this pin acts as an input
for an external power supply capable of providing +5volts +/-10% at up to
100mA to provide power to the isolated circuitry of the SDM-CAN.
The 3-way terminal block and CIA connector are connected in
parallel internally and are not two separate connections to
different CAN interfaces. NOTE
Please refer to the documentation for your CAN network to check the preferred
method of connection. For many applications various standards will apply
giving recommended practices for connection. Apart from the choice of
connector some standards recommend different ways of ‘tapping’ into CAN
networks and also recommend maximum lengths for ‘T’s or ‘stubs’ off the
network. For instance, at the highest baud rate of 1Mbit/s, ISO11898
recommends a maximum bus length of 40 m and a maximum stub length of 0.3
m. These lengths increase significantly at lower bit rates.
As discussed above you also need to consider:
• If the SDM-CAN should terminate the network
• If it should be configured in isolated mode
• If transmission should be enabled
• The source of power for the isolation hardware.
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