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NI-CAN Channel Data Bit Limits

Primary Software: Driver Software>>NI-CAN
Primary Software Version: 1.1
Primary Software Fixed Version: N/A
Secondary Software: N/A

Problem:
Why do I receive the error "Integer channel can contain a max. of 52 bits" in the CAN Channel Properties utility within Measurement & Automation Explorer (MAX)? I need to use all 64 bits available in the channel, how can I get around this error?

Solution:
CAN messages have a maximum of 8 data bytes or 64 data bits available for channel data.  Whether you can use all 64 bits of this data depends on the data type you select for the channel data.  Signed or unsigned data types can utilize a maximum of 52 data bits.  Only IEEE float data types can utilize all 64 data bits.

If you do set a channel bit length greater than 52 bits for an signed or unsigned data type, MAX will throw the following error.

There are two options available to resolve this error. 
  • If your application requires signed or unsigned data types, reduce the number of data bits to 52 or less. 
  • If your application requires 52 to 64 data bits, you must change the data type to IEEE float.


Related Links:
Developer Zone Tutorial: The NI-CAN Channel API

Attachments:
CANChannelProperties.PNG

Report Date: 12/07/2007
Last Updated: 02/07/2008
Document ID: 4G6ARQKQ

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