Campbell Scientific SDM-CAN Datalogger to CANbus Interface - Manual (Page 14)

SDM-CAN Datalogger-to-CANbus Interface
3) If running in isolated mode decide whether the SDM-CAN will supply
power via a built-in DC-DC converter for the isolated CAN interface
components, or whether power will be sourced from an external supply.
Using a converter adds 40-50mA to the power consumption of the SDM-
CAN when it is active. However, if a converter is not used, power must be
provided from elsewhere (see below). The default setting is for the
converter to be OFF, although for many applications you may need to turn
it on once you have considered the implications for your power supply.
4) Decide whether the transmit functions of the SDM-CAN interface need to
be enabled in hardware. The disabled mode of operation is the safest,
especially in vehicle applications, as it avoids the risk of the SDM-CAN
sending bad data onto the CAN network. However, in some modes of
operation, transmission is obligatory e.g. to let the SDM-CAN request
data, acknowledge data or to transmit data onto the bus. If transmission is
to be enabled, the relevant jumpers need to be changed. Additionally
transmission must be enabled by sending the SDM-CAN an instruction
which both enables and specifies the method of transmission. See Section
3.3, The Datalogger Instruction, data type 32, below.
Access to the jumpers requires the removal of the lid of the SDM-CAN. Please
follow anti-static precautions during the removal of the lid and also when
changing the jumpers. Refer to FIGURE 2-1 for details of the jumper positions.
Labels are also provided in white writing on the circuit board.
If white jumper block not fitted then refer to FIGURE 2-2 for isolation enabled
and FIGURE 2-3 for isolation disabled.
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