National Instruments NI 9853 - Manual (Page 4)

NI 9853 Operating Instructions 4 ni.com
Caution For Zone 2 applications, install a protection
device between the CAN signals and the NI 9853 CAN
pins. The device must prevent the CAN Port-to-COM
voltage from exceeding 55 V if there is a transient
overvoltage condition.
Special Conditions for Safe Use in Europe
This equipment has been evaluated as EEx nA II T4 equipment
under DEMKO Certificate No. 03 ATEX 0324020X. Each module
is marked
II 3G and is suitable for use in Zone 2 hazardous
locations.
Wiring the NI 9853
The NI 9853 has two 9-pin male D-Sub connectors that provide
connections to a CAN bus. Each port on the NI 9853 has pins for
CAN_H and CAN_L, to which you connect the CAN bus signals.
These signals should be connected using twisted-pair cable.
Each port has two common pins (COM) that are internally
connected to the isolated reference of the module and serve as the
reference ground for CAN_H and CAN_L. You can connect the
CAN bus reference ground (sometimes referred to as CAN_V–) to