Re: Single shot mode with arbitration support

Hi John,

The revision history of MilCAN A Complete Rev3 has as first entry

> 
> 1		March 2006		Initial publication.
> Merger of the following documents: MilCAN A Physical Layer Specification (IHSDB-APP-GEN-D-030 Rev 3)
> MilCAN A Data Link Layer Specification (IHSDB-APP-GEN-D-031 Rev 4)  *********
> MilCAN A Application Layer Specification (IHSDB-APP-GEN-D-032 Rev 2)

Looks like the specification you referenced is now included in MilCAN A, rev3.

Paragraph 3.10 becomes 3.2.10

> 	• 3.2.10  Link Layer Re-transmission on Error - Compulsory
> 
> The LLC sub-layer of the ISO11898 CAN standard includes amongst its functions the re- transmission of frames that have been disrupted by errors during transmission. This process can result in an unpredictable number of re-transmissions of the same frame in the event of errors.
> 
> Automatic re-transmission on error shall be prohibited where this would violate the requirements of prioritised queuing as stated in section 3.2.7.1. Corrective procedures appropriate for the system application may then be executed by the node/device application software.

To me this defines the requirement for disabling automatic re-transmission. But this doesn't say anything about not having an error flag.

I can't really imagine that a CAN HLP disallows an essential CAN feature such as the error flag.


Regards,
Daniel




On Jan 17, 2013, at 6:46 PM, John Dammyer <[email protected]> wrote:

> Hi Daniel,
> 
> See below.  Unless it's changed.
> 
> John
> 
> From:
> MilCAN A
> Data Link Layer Specification
> IHSDB-APP-GEN-D-031
> Revision 4
> 
> 3.10 Link Layer Re-transmission on Error - Compulsory
> The LLC sub-layer of the ISO11898 CAN standard includes amongst its
> functions the retransmission
> of frames that have been disrupted by errors during transmission. This
> process can result in an unpredictable number of re-transmissions of the
> same frame in
> the event of errors.
> This function shall be disabled by selecting CAN controllers that provide
> the capability to
> disable re-transmissions. Corrective procedures appropriate for the system
> application
> may then be executed by the node/device application software
> 
> 
> 
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Daniel Leu
> Sent: January-17-13 6:09 PM
> To: [email protected]
> Subject: Re: [CANLIST] Single shot mode with arbitration support
> 
> Hi John,
> 
>> The problem is MilCAN doesn't allow error flags since a bad message 
>> retrying could easily overlap into the next SYNC message window.  The 
>> architecture of a MilCAN system is such that the designer plans what 
>> messages occur during each SYNC slot.  A node may broadcast only when the
> SYNC COUNTER was 24.
>> Another only when 32 and so on.   
> 
> Just wondering where in the MilCAN spec it says that error flags are not
> allowed. Thanks!
> 
> 
> Regards,
> Daniel
> 
> 
> 
> 
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