CAN_Remote_frames

[N.Swathi]

Hi

Can anybody tell whats remote frame in CAN. when CAN node receives the
remote frame what does it do.

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[Corrigan, Steve]

Hello,

The intended purpose of the remote frame is to solicit the transmission of data from another node. The
remote frame is similar to the data frame, with two important differences. First, this type of message is
explicitly marked as a remote frame by a recessive RTR bit in the arbitration field, and secondly, there is
no data

Cheers,
Steve C.

-----Original Message-----
From: canlist-owner@... [mailto:canlist-owner@...] On Behalf Of N.Swathi
Sent: Thursday, June 26, 2008 4:15 AM
To: canlist@...
Subject: [CANLIST] CAN_Remote_frames

Hi

Can anybody tell whats remote frame in CAN. when CAN node receives the remote frame what does it do.

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>
--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[John Dammeyer]

Hi,

The data sheet explains how to make a remote frame.  The first few CAN
devices didn't do much with them.  Just raised a message available
signal and it was up to the application in the device to decide what to
do.  All in all, not much more use than a non-remote frame with 0 length
data.

Now, more of the newer CAN devices and FPGA cores handle remote frames
autonomously.  

I suspect your question may be more along the lines of how would a
remote frame be used?

Ideally, your small 'device' node will run on some sort of periodic
clock acquiring data, perhaps processing it and putting the results into
a CAN message object.  However, rather than broadcasting this
information the CAN message object is defined to just have the most
recent data but not send.  Any node that wants this information needs to
only ask.  It does this by sending a remote frame.

The frame has an ID and the remote flag set along with a byte count.
The CAN engine in the target node (the one with filters set to receive
that message) immediately responds and send the message object with the
same ID but without the remote flag set and this time there are N data
bytes.  Meanwhile the 'device' node will continue to update the message
object never knowing whether anyone uses the information or not.  

So you get two messages on the bus, back to back, ideally with only the
shortest interframe space between them serving as a request/reply
sequence.  Note that not all CAN engines can do this.  You have to read
the data sheet to see if it does.  If it doesn't your device node will
respond to the RTR message and then flag a message for transmission.
The only difference is it interrupts the device node and results in
latency from the request to the reply.

John Dammeyer



> Behalf Of N.Swathi
> Hi
>
> Can anybody tell whats remote frame in CAN. when CAN node
> receives the
> remote frame what does it do.


Automation Artisans Inc.
http://www.autoartisans.com
Ph. 1 250 544 4950

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[N.Swathi]

Thanks John,
ya u r right. I have CAN transmitter and receiver which acquires the data on periodic clock.. Basically in VLSI platform.
when  I receive the remote frame. whatever data captured from remote frame should be kept as it is add the data from fifo calculate CRC and send it.
or when I receive remote frame I need to check whether the identifier matches with the identifier of mine or not. if it matches send the data frame with the same id as remote frame received.

Swathi

John Dammeyer wrote:

Hi,

The data sheet explains how to make a remote frame.  The first few CAN
devices didn't do much with them.  Just raised a message available
signal and it was up to the application in the device to decide what to
do.  All in all, not much more use than a non-remote frame with 0 length
data.

Now, more of the newer CAN devices and FPGA cores handle remote frames
autonomously.  

I suspect your question may be more along the lines of how would a
remote frame be used?

Ideally, your small 'device' node will run on some sort of periodic
clock acquiring data, perhaps processing it and putting the results into
a CAN message object.  However, rather than broadcasting this
information the CAN message object is defined to just have the most
recent data but not send.  Any node that wants this information needs to
only ask.  It does this by sending a remote frame.

The frame has an ID and the remote flag set along with a byte count.
The CAN engine in the target node (the one with filters set to receive
that message) immediately responds and send the message object with the
same ID but without the remote flag set and this time there are N data
bytes.  Meanwhile the 'device' node will continue to update the message
object never knowing whether anyone uses the information or not.  

So you get two messages on the bus, back to back, ideally with only the
shortest interframe space between them serving as a request/reply
sequence.  Note that not all CAN engines can do this.  You have to read
the data sheet to see if it does.  If it doesn't your device node will
respond to the RTR message and then flag a message for transmission.
The only difference is it interrupts the device node and results in
latency from the request to the reply.

John Dammeyer



  

Behalf Of N.Swathi
Hi

Can anybody tell whats remote frame in CAN. when CAN node 
receives the 
remote frame what does it do.
    

Automation Artisans Inc.
http://www.autoartisans.com
Ph. 1 250 544 4950

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to canlist-owner@...


  

[Peter Lauer]

Some parts of this message have been removed. Learn more about Nabble's security policy.

Simple question,
 
I can run a J1939 (29bit) and CANopen (11bit) node on the same bus, as long as they run the same bitrate?
 
regards
 
Peter

[Torsten Krahl]

Dear Mr. Lauer,
> I can run a J1939 (29bit) and CANopen (11bit) node on the same bus, as
> long as they run the same bitrate?
Yes, as long as all devices support 29bit ( in the CAN controller ). And
even CANopen does support 29bit IDs for example in the PDOs.


 
Mit freundlichen Gruessen
With best regards

Torsten M. Krahl


--------------------------------
http://www.MicroControl.net
mailto:krahl@...

Fon: +49 (0)2241 / 256 59 - 0
Fax: [phone] / 256 59 - 11

MicroControl GmbH & Co. KG
Lindlaustr. 2 c
53842 Troisdorf, Germany

Persönlich haftend:
MicroControl Systemhaus für Automatisierung Beteiligungsgesellschaft mbH, Troisdorf

HRB 4952 Siegburg (GmbH)  HRA 3110 Siegburg (KG)

Geschäftsführer:
Dipl.-Ing. Uwe Koppe
Dipl.-Ing. (FH) Torsten Krahl
Dipl.-Ing. (FH) Frank Wielpütz

Ust-IdNr. DE 812191199
--------------------------------

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[Bram Kerkhof]

Some parts of this message have been removed. Learn more about Nabble's security policy.

I’m not sure about the CANopen protocol, but the J1939 protocol stack should just ignore 11bit messages on the bus. Keep in mind however that this also depends on the implementation of the J1939 node, as I’ve seen some ECUs that use J1939 for general operation and have a proprietary diag protocol using 11bit CAN.

 

So I guess the answer really is: depends on your environment.

 

Cheers,

Bram

 

From: canlist-owner@... [mailto:canlist-owner@...] On Behalf Of Peter Lauer
Sent: woensdag 17 september 2008 14:54
To: canlist@...
Subject: [CANLIST] simple question 11bit / 29bit ID

 

Simple question,
 
I can run a J1939 (29bit) and CANopen (11bit) node on the same bus, as long as they run the same bitrate?
 
regards
 
Peter

[Funny N.]

Some parts of this message have been removed. Learn more about Nabble's security policy.

We are doing this for quite some time, it seems working quite well at 250K bps.

Though We do see a relatively slower data passing through rate on a 500K bps test network when mixing the 11-bit and 29-bit devices. It is a bit strange.

 

Funny N.
Au Group Electronics, New Bedford, MA, http://www.AuElectronics.com

----- Original Message ----
From: Peter Lauer <plauer@...>
To: canlist@...
Sent: Wednesday, September 17, 2008 8:53:49 AM
Subject: [CANLIST] simple question 11bit / 29bit ID

Simple question,
 
I can run a J1939 (29bit) and CANopen (11bit) node on the same bus, as long as they run the same bitrate?
 
regards
 
Peter

[stunbmun]

Do any higher level protocols use remote frames?  Is the ID in the remote frame the ID that is being requested?  

[Torsten Krahl]

Hi Jon,
> Do any higher level protocols use remote frames?  Is the ID in the remote
> frame the ID that is being requested?  
>  
Yes, Remot Frames are defined in CANopen protocol for example for
"Polling of PDOs" and also for Node-Guarding Protocol. And the ID in the
frame is the requested ID. But there is a recommandation from the user´s
organization CiA ( www.can-cia.org ) not to use Remote Frames ( if
possible ). Since in the past ( and still excisting ) there are variuous
problems which can be seen when using Remotes in an network.

Mit freundlichen Gruessen
With best regards

Torsten M. Krahl


--------------------------------
http://www.MicroControl.net
mailto:krahl@...

Fon: +49 (0)2241 / 256 59 - 0
Fax: [phone] / 256 59 - 11

MicroControl GmbH & Co. KG
Lindlaustr. 2 c
53842 Troisdorf, Germany

Persönlich haftend:
MicroControl Systemhaus für Automatisierung Beteiligungsgesellschaft mbH, Troisdorf

HRB 4952 Siegburg (GmbH)  HRA 3110 Siegburg (KG)

Geschäftsführer:
Dipl.-Ing. Uwe Koppe
Dipl.-Ing. (FH) Torsten Krahl
Dipl.-Ing. (FH) Frank Wielpütz

Ust-IdNr. DE 812191199
--------------------------------

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[Heinz-Juergen Oertel]

Hi John,

Am Donnerstag 18 September 2008 schrieb stunbmun:
> Do any higher level protocols use remote frames?

Yes. For example CANopen defines RTR requested PDOs. But, on the other
hand, CiA recommends not to use RTR.
The old CANopen Node Guarding protocoll is based on RTR frames.


> Is the ID in the
> remote frame the ID that is being requested?

Thats the nature of the CAN RTR mechanism.

 Heinz

[Peter Lauer]

Some parts of this message have been removed. Learn more about Nabble's security policy.

Hi,
 
does anybody has experiance with the Deerborn USB (or RS232) to CAN adapter, called DPA?
I wondered about the driver API.
We have a CAN tool working with Value CAN and KVASER CAN adapters, and want to be able to use the DPA as well.
 
regards
 
Peter

[Peter Lauer]

where can I find a copy of the RP1210 spec / api description?

regards

Peter--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[Peter Lauer]

I found that reference too, but it does not explain the individual commands. Why is the specification not on the web?

Peter


Email von Peter Lauerplauer@...

----------------------------------------

> From: hakan.carlsson@...
> To: plauer@...
> Subject: SV: [CANLIST] RP1210
> Date: Wed, 8 Oct 2008 08:42:07 +0200
>
> Hi Peter,
>
> I hope our web site can give you a quick start or not on this subject:
>
> http://www.kvaser.com/can/misc/rp1210/rp1210-a-b.htm
>
> ------
> Best Regards,
> Håkan Carlsson
>
> Switchboard: [phone]
> Direct: [phone] extension 387
> Fax: [phone]
> Work cell: [phone]
> E-mail: hakan.carlsson@...
> SkypeID: carlsson121
> Postal address: Kvaser AB, Aminogatan 25A, SE43153 Mölndal, Sweden
>
>
>
>
> -----Ursprungligt meddelande-----
> Från: canlist-owner@...
> [mailto:canlist-owner@...] För Peter Lauer
> Skickat: den 8 oktober 2008 04:48
> Till: canlist@...
> Ämne: [CANLIST] RP1210
>
>
> where can I find a copy of the RP1210 spec / api description?
>
> regards
>
> Peter--
> Archives and useful links: http://groups.yahoo.com/group/CANbus
> Subscribe and unsubscribe at www.vector-informatik.com/canlist/
> Report any problems to
>
>
>

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>

[Peter Lauer]

Some parts of this message have been removed. Learn more about Nabble's security policy.

I don't seem to get a lot of feedback on the RP 1210 issue.  Nobody seems to have the original specs or being real interested in it.

Peter

Email von Peter Lauer plauer@...

---

> From: plauer@...

> To: canlist@...
> Subject: RE: SV: [CANLIST] RP1210
> Date: Wed, 8 Oct 2008 11:56:45 +0000
>
>
> I found that reference too, but it does not explain the individual commands. Why is the specification not on the web?
>
> Peter
>
>
> Email von Peter Lauerplauer@...
>
> ----------------------------------------
> > From: hakan.carlsson@...
> > To: plauer@...
> > Subject: SV: [CANLIST] RP1210
> > Date: Wed, 8 Oct 2008 08:42:07 +0200
> >
> > Hi Peter,
> >
> > I hope our web site can give you a quick start or not on this subject:
> >
> > http://www.kvaser.com/can/misc/rp1210/rp1210-a-b.htm
> >
> > ------
> > Best Regards,
> > Håkan Carlsson
> >
> > Switchboard: [phone]
> > Direct: [phone] extension 387
> > Fax: [phone]
> > Work cell: [phone]
> > E-mail: hakan.carlsson@...
> > SkypeID: carlsson121
> > Postal address: Kvaser AB, Aminogatan 25A, SE43153 Mölndal, Sweden
> >
> >
> >
> >
> > -----Ursprungligt meddelande-----
> > Från: canlist-owner@...
> > [mailto:canlist-owner@...] För Peter Lauer
> > Skickat: den 8 oktober 2008 04:48
> > Till: canlist@...
> > Ämne: [CANLIST] RP1210
> >
> >
> > where can I find a copy of the RP1210 spec / api description?
> >
> > regards
> >
> > Peter--
> > Archives and useful links: http://groups.yahoo.com/group/CANbus
> > Subscribe and unsubscribe at www.vector-informatik.com/canlist/
> > Report any problems to
> >
> >
> >

[Ralph Merwin]

Peter,

According to Dearborn's web page:

http://www.dgtech.com/product/dpa/software/software.htm

the RP1210 spec can be purchased from the TMC at [phone].


Sample code using the RP1210 API can also be found on a Dearborn page:

http://www.dgtech.com/product/dpa/example/example.php

Ralph



--- On Thu, 10/9/08, Peter Lauer <plauer@...> wrote:

> From: Peter Lauer <plauer@...>
> Subject: [CANLIST] RP1210
> To: canlist@...
> Date: Thursday, October 9, 2008, 4:54 AM
> I don't seem to get a lot of feedback on the RP 1210
> issue.  Nobody seems to have the original specs or being
> real interested in it.
>
> Peter
>
> Email von Peter Lauer
>
> plauer@...
>
>
>
> > From: plauer@...
> > To: canlist@...
> > Subject: RE: SV: [CANLIST] RP1210
> > Date: Wed, 8 Oct 2008 11:56:45 +0000
> >
> >
> > I found that reference too, but it does not explain
> the individual commands. Why is the specification not on the
> web?
> >
> > Peter
> >
> >
> > Email von Peter Lauerplauer@...
> >
> > ----------------------------------------
> > > From: hakan.carlsson@...
> > > To: plauer@...
> > > Subject: SV: [CANLIST] RP1210
> > > Date: Wed, 8 Oct 2008 08:42:07 +0200
> > >
> > > Hi Peter,
> > >
> > > I hope our web site can give you a quick start or
> not on this subject:
> > >
> > >
> http://www.kvaser.com/can/misc/rp1210/rp1210-a-b.htm
> > >
> > > ------
> > > Best Regards,
> > > Håkan Carlsson
> > >
> > > Switchboard: [phone]
> > > Direct: [phone] extension 387
> > > Fax: [phone]
> > > Work cell: [phone]
> > > E-mail: hakan.carlsson@...
> > > SkypeID: carlsson121
> > > Postal address: Kvaser AB, Aminogatan 25A,
> SE43153 Mölndal, Sweden
> > >
> > >
> > >
> > >
> > > -----Ursprungligt meddelande-----
> > > Från:
> canlist-owner@...
> > >
> [mailto:canlist-owner@...] För
> Peter Lauer
> > > Skickat: den 8 oktober 2008 04:48
> > > Till: canlist@...
> > > Ämne: [CANLIST] RP1210
> > >
> > >
> > > where can I find a copy of the RP1210 spec / api
> description?
> > >
> > > regards
> > >
> > > Peter--
> > > Archives and useful links:
> http://groups.yahoo.com/group/CANbus
> > > Subscribe and unsubscribe at
> www.vector-informatik.com/canlist/
> > > Report any problems to
> > >
> > >
> > >

--
Archives and useful links: http://groups.yahoo.com/group/CANbus
Subscribe and unsubscribe at www.vector-informatik.com/canlist/
Report any problems to <canlist-owner@...>