How Do Multiplexed Signals Work In NI-XNET Database Editor?

Updated Jun 21, 2019

Reported In

Driver

  • NI-XNET

Issue Details

I am trying to build a database with multiplexed signals, but I do not know how do signal multiplexing works in the NI-XNET Database Editor.

Solution

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).
 

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.

WAS THIS ARTICLE HELPFUL?

Not Helpful