Detec­tion of short cir­cuits in the CAN bus – Error patterns

The robust­ness of the CAN bus also based on its tole­ran­ce to occur­ring short cir­cuits. In the fol­lowing, we sum­ma­ri­ze the pos­si­bi­li­ties and show how the CAN­touch detects the­se errors.

Case Descrip­ti­on Com­mu­ni­ca­ti­on CAN­touch

Bus Sta­tus

CAN­touch 

CAN Levels
Absolute

CAN­touch

Node Mea­su­re­ment

CAN­touch

Bus Wiring

OK

CAN-Bus without errors

yes
Remark I Bus Sta­tus: valid CAN messages available

 
CAN_​H
shor­ted to
CAN_V+

 
no Test set­up without communication
Remark Vdepends on the CAN trans­cei­ver type, some types can still com­mu­ni­ca­te with this error

Remark VIdepen­ding on the vol­ta­ge level and the dura­ti­on of the error (over­hea­ting of the CAN transceiver)

Remark IIBus Sta­tus: sta­ti­cal­ly recessive Remark IVMea­su­re­ment not pos­si­ble without communication Remark IIIfinds errors when sup­ply vol­ta­ges are mea­su­red too


CAN_​L
shor­ted to
CAN_V+


no Test set­up without communication
Remark Vdepends on the CAN trans­cei­ver type, some types can still com­mu­ni­ca­te with this error Remark IIBus Sta­tus: sta­ti­cal­ly recessive Remark IVMea­su­re­ment not pos­si­ble without communication Remark IIIfinds errors when sup­ply vol­ta­ges are mea­su­red too


CAN_​H
shor­ted to
Vcc


yes
Remark I Bus Sta­tus: valid CAN messages available Remark VII Error in dif­fe­ren­ti­al signal not detectable Remark VIIIA wiring test with con­nec­ted par­ti­ci­pants remains not recom­men­ded. It pro­vi­des unde­fi­ned errors who­se state­ments are dif­fi­cult to judge. The dis­play­ed results depend stron­gly on the inter­nal wiring of the participants.


CAN_​L
shor­ted to
Vcc


no
Remark IIBus Sta­tus: sta­ti­cal­ly recessive Remark IVMea­su­re­ment not pos­si­ble without communication Remark VIIIA wiring test with con­nec­ted par­ti­ci­pants remains not recom­men­ded. It pro­vi­des unde­fi­ned errors who­se state­ments are dif­fi­cult to judge. The dis­play­ed results depend stron­gly on the inter­nal wiring of the participants.


CAN_​H
shor­ted to
CAN_V-


no
Remark IIBus Sta­tus: sta­ti­cal­ly recessive Remark IVMea­su­re­ment not pos­si­ble without communication Remark IIIfinds errors when sup­ply vol­ta­ges are mea­su­red too


CAN_​L
shor­ted to
CAN_V-


yes
Remark VII Error in dif­fe­ren­ti­al signal not detectable Remark IIIfinds errors when sup­ply vol­ta­ges are mea­su­red too


CAN_​H
shor­ted to
CAN_L


no
Remark IIBus Sta­tus: sta­ti­cal­ly recessive Remark IVMea­su­re­ment not pos­si­ble without communication

Legend:

Vcc: Sup­ply vol­ta­ge of the CAN transceiver

I) Bus Sta­tus: valid CAN messages available

II) Bus Sta­tus: sta­ti­cal­ly recessive

III) finds errors when sup­ply vol­ta­ges are mea­su­red too

IV) Mea­su­re­ment not pos­si­ble without communication

V) depends on the CAN trans­cei­ver type, some types can still com­mu­ni­ca­te with this error

VI) depen­ding on the vol­ta­ge level and the dura­ti­on of the error (over­hea­ting of the CAN transceiver)

VII) Error in dif­fe­ren­ti­al signal not detectable

VIII) A wiring test with con­nec­ted par­ti­ci­pants remains not recom­men­ded. It pro­vi­des unde­fi­ned errors who­se state­ments are dif­fi­cult to judge. The dis­play­ed results depend stron­gly on the inter­nal wiring of the participants.

Article last edited on Article first published on
2020/​01/​08 2019/​09/​30