Multiplexed signals are two separate signals that occupy the same bit space in a CAN frame. They are linked by a separate signal called the Multiplexer, which determines which signal gets to occupy that bit space in that particular frame instance.
For example:We define a CAN frame with a one-byte payload. Bit 0 will be the multiplexer and it could be either a 0 or a 1:
The bits 1 to 7 will be a 7-bit signal. We define the signals to occupy the same space, but with different Multiplexed values or
modes.
When the Multiplexer = 0, the 7-bit signal will represent one specific measurement (RPM for example):
When the Multiplexer = 1, the 7-bit signal will represent a different measurement (tire pressure, for example).
LabVIEW Example for a Multiplexed loopback Test bases on this Database:This example performs a loopback test for a Multiplexed Frame.
Requirements:
- LabVIEW 2019
- NI-XNET Driver
- XNET Hardware
- Multiplexed Signals Example DB.xml
Instruction:
- Download the attached "Multiplexed Signals Example DB.xml" and add it to your XNET DB Aliases on your System so you can select it in LabVIEW.
- Ensure that you have connected the selected CAN ports with a properly terminated cable. If you do not have a terminated cable, select Yes in Termination? to enable internal termination.
- Run the VI.
Additional Information
Multiplexed Signals are currently supported only for CAN. A frame may only contain one multiplexer signal. Multiplexer signals may be up to 16 bits in size. Furthermore, a static signal cannot share the same position on the frame with a multiplexed signal.