[etherlab-users] Domain offset overlap

[Gavin Lambert]

It also returns an error if something does not byte-align and you provide
NULL for the bit_position argument.  So you shouldn't see any overlapping
offsets as a result of this unless you're throwing away data.

 

From: etherlab-users-bounces at etherlab.org
[mailto:etherlab-users-bounces at etherlab.org] On Behalf Of Dave Page
Sent: Thursday, 10 April 2014 10:07
To: Steve Hartmann; etherlab-users at etherlab.org
Subject: Re: [etherlab-users] Domain offset overlap

 

Hi,

    Sorry, I misinterpreted your message. 

    ecrt_slave_config_reg_pdo_entry can produce apparently overlapping
offsets when the PDO data is not on even bit boundaries (not divisible by
8). 

    You may wish to use the unsigned int *bit_position argument to discover
the bit offsets of your data.

        Best regards - Dave

On 09-Apr-14 15:49, Steve Hartmann wrote:

Hi Dave,

 

Thanks for the reply.  I am not using TwinCAT at all.  Also, please forgive
my ignorance, but what is the "LRW command".

 

I'm not sure how to deal with this with the etherlab stack.  If it give me a
domain offset of 3 for two different slices (one input and one output), how
do I deal with this overlapped data?

 

Thanks,

 

Steven

 

 

From: Dave Page <dave.page at gleeble.com>
Date: Wednesday, April 9, 2014 2:45 PM
To: Etherlab Users <etherlab-users at etherlab.org>
Subject: Re: [etherlab-users] Domain offset overlap

 


    In order to reduce process data size, TwinCAT overlaps the RxPDO and
TxPDO for each module, then uses the LRW command to effect the transfer. So,
I believe what you're seeing is normal.

        Best regards - Dave Page

On 09-Apr-14 15:41, etherlab-users-request at etherlab.org wrote:

Message: 1
Date: Wed, 9 Apr 2014 19:41:29 +0000
From: Steve Hartmann  <mailto:shartmann at militho.com> <shartmann at militho.com>
To: Etherlab Users  <mailto:etherlab-users at etherlab.org>
<etherlab-users at etherlab.org>
Subject: [etherlab-users] Domain offset overlap
Message-ID:  <mailto:CF6B0C97.F827%25shartmann at militho.com>
<CF6B0C97.F827%shartmann at militho.com>
Content-Type: text/plain; charset="us-ascii"
 
Hi all,
 
I have written some code to parse the generated XML file from "ethercat xml"
and use that to configure the ethercat stack.  The problem I am having is
the output from ecrt_slave_config_ret_pdo_entry produces overlapped offsets.
I also tried using ecrt_slave_config_reg_pdo_entry_pos with the same
results.  This is a very simple test rig that has one each of DO, DI, AO,
and AI slices - all beckhoff.  I have attached a file which includes the
generated XML file, the code in question, and the log output.  Does anyone
know what I am doing wrong?
 
Best regards,
 
Steven Hartmann

 

-- 

  _____  

David Page, Chief Embedded Architect
Dynamic Systems Inc.
PO Box 1234
Poestenkill, NY 12140
Telephone: +1 (518) 283-5350 | Fax: +1 (518) 283-3160 | 

 

-- 

  _____  

David Page, Chief Embedded Architect
Dynamic Systems Inc.
PO Box 1234
Poestenkill, NY 12140
Telephone: +1 (518) 283-5350 | Fax: +1 (518) 283-3160 | 

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