National Instruments NI-CAN User Manual page 42

Frame Ignored
Yes
Frame Ignored
No
© National Instruments Corporation
CAN Objects. The flowchart in Figure 3-1 shows the steps performed by
NI-CAN when a CAN frame is received.
Frame Received
Arbitration ID
Handled by an Open
CAN Object?
Standard or
Extended Frame?
Standard
Standard
Comparator Disabled
(NC_CAN_ARBID_NONE)?
No
Apply Standard Mask
Masked
Arbitration ID
Equal to Standard
Comparator
Place Frame Into Read Queue of
CAN Network Interface Object
Figure 3-1. Flowchart for CAN Frame Reception
The decisions in Figure 3-1 are generally performed by the on-board CAN
communications controller chip. Nevertheless, if you intend to use CAN
Objects as the sole means of receiving CAN frames, it is best to disable all
frame reception in the CAN Network Interface Object by setting the
Chapter 3
Yes
No
Data
Frame?
No
Yes
Extended
Extended
Comparator Disabled
(NC_CAN_ARBID_NONE)?
No
Apply Extended Mask
Masked
Arbitration ID
Equal to Extended
Yes
Comparator
3-3
NI-CAN Programming Techniques
CAN Object Uses Frame
CAN Network Interface Object
Frame Ignored
Frame Ignored
Yes
Frame Ignored
No
NI-CAN User Manual