Contemporary Control Systems CANPCI - Manual (Page 5)

TD020900-0IC
5
OpERATION
CANbus Transceiver Power
The CANpCI-CO takes it transceiver power from the host computer, but
an onboard DC-DC converter provides 1500 volts of galvanic isolation.
The CANpCI-DN obtains its transceiver power from the CANbus, but
an onboard circuit is provided to regulate that voltage to a constant 5 V.
DeviceNet Reverse Voltage Protection
The CANPCI-DN is protected from excessive voltage if the DeviceNet
power connections are accidentally reversed. However, this protection
results in the CANPCI-DN ground being about 700 mV above the
CANbus ground.