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.