IDX with CAN: Meaning of X1 / X2 "CAN_V+" pin

Topic:

• What is the purpose of the pin "CAN_V+" present by the two CAN connectors (X1, X2) of the IDX?
• Is it necessary to provide a supply voltage to "CAN_V+"?

Solution:

The IDX uses a 5-pole industrial M8 connector for the "CAN IN (X1)" and "CAN OUT (X2)".

These two connectors have the following pin assignment:

Important:

• The "CAN_V+" is not in use by the IDX but just looped in between connector the "CAN IN" X1 and "CAN OUT" X2 connector.
• There is no(!) need to supply a voltage to "CAN_V+". The IDX and its bus communication can be operated without a supply voltage present at "CAN_V+".

Technical background:

• The "CAN_V+" is internally only looped through from CAN connector X1 to X2 but the IDX does not(!) use this supply voltage. 
• The CiA 303-1 "Cabling and Connector Pin Assignment" standard defines "CAN_V+" the following way:
  "Optional CAN external positive supply (dedicated for supply of transceivers and opto-couplers, if galvanic isolation of the bus nodes applies)."
• The IDX has no(!) galvanic isolated CAN bus but still offers the "CAN_V+" pin.
  • The "CAN_V+" pin makes it easy to  use an identical CAN network cabling and supply voltage forwarding to any CAN device which might demand for that supply voltage.
  • If there is a voltage present at IDX "CAN_V+" pin, it is simply looped from the IDX's "CAN IN" (X1) to the "CAN OUT" (X2) connector. Any CAN devices requiring this supply voltage can use it without any impact on the IDX or any special wiring.