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<p class="MsoNormal">Hi,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve made some progress and now I can get all the slaves to OP and exchange data with the master.<o:p></o:p></p>
<p class="MsoNormal">Fragmentation is working properly and can be seen clearly in a wireshark capture.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I have 7 slaves that support overlapping PDOs with PDO domains of 68 and 241 bytes, and an 8<sup>th</sup> slave that doesn’t support overlapping PDOs with PDO domains of 35 and 33 bytes.<o:p></o:p></p>
<p class="MsoNormal">In dmesg, coming out of domain.c, ec_domain_add_fmmu_config():<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">[ 78.299113] Domain 0: fmmu f08d0924 Added 68 bytes at 0.<o:p></o:p></p>
<p class="MsoNormal">[ 78.306251] Domain 0: fmmu f08d0944 Added 241 bytes at 0.<o:p></o:p></p>
<p class="MsoNormal">[ 78.317895] Domain 0: fmmu f08d1124 Added 68 bytes at 241.<o:p></o:p></p>
<p class="MsoNormal">[ 78.325476] Domain 0: fmmu f08d1144 Added 241 bytes at 241.<o:p></o:p></p>
<p class="MsoNormal">[ 78.337518] Domain 0: fmmu f08d1924 Added 68 bytes at 482.<o:p></o:p></p>
<p class="MsoNormal">[ 78.345279] Domain 0: fmmu f08d1944 Added 241 bytes at 482.<o:p></o:p></p>
<p class="MsoNormal">[ 78.357735] Domain 0: fmmu f08d2124 Added 68 bytes at 723.<o:p></o:p></p>
<p class="MsoNormal">[ 78.365580] Domain 0: fmmu f08d2144 Added 241 bytes at 723.<o:p></o:p></p>
<p class="MsoNormal">[ 78.378337] Domain 0: fmmu f08d2924 Added 68 bytes at 964.<o:p></o:p></p>
<p class="MsoNormal">[ 78.386187] Domain 0: fmmu f08d2944 Added 241 bytes at 964.<o:p></o:p></p>
<p class="MsoNormal">[ 78.403592] Domain 0: fmmu f08d3124 Added 68 bytes at 1205.<o:p></o:p></p>
<p class="MsoNormal">[ 78.411901] Domain 0: fmmu f08d3144 Added 241 bytes at 1205.<o:p></o:p></p>
<p class="MsoNormal">[ 78.425531] Domain 0: fmmu f08d3924 Added 68 bytes at 1446.<o:p></o:p></p>
<p class="MsoNormal">[ 78.433643] Domain 0: fmmu f08d3944 Added 241 bytes at 1446.<o:p></o:p></p>
<p class="MsoNormal">[ 78.447590] Domain 0: fmmu f08d0124 Added 35 bytes at 1687.<o:p></o:p></p>
<p class="MsoNormal">[ 78.454539] Domain 0: fmmu f08d0144 Added 33 bytes at 1722.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">So in the case of overlapping PDOs, both Rx and Tx FMMUs have logical_domain_offset of equal values. If a slave does not support overlapping PDOs, the FMMUs logical_domain_offset have different values.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Then in domain.c, ec_domain_finish(), in the loop list_for_each_entry(fmmu, &domain->fmmu_configs, list)<o:p></o:p></p>
<p class="MsoNormal">The condition<o:p></o:p></p>
<p class="MsoNormal">if (fmmu->logical_domain_offset >= candidate_start)<o:p></o:p></p>
<p class="MsoNormal">is met when a slave’s first FMMU is evaluated, then candidate_start is added with fmmu->data_size.<o:p></o:p></p>
<p class="MsoNormal">The condition is never met with the second slave’s FMMU, that bares the same value logical_domain_offset like the prior FMMU.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Completely removing the condition<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">if (fmmu->logical_domain_offset >= candidate_start)<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">fixed the problem for me, though I’m not sure whether this code change is the best way to solve the problem…<o:p></o:p></p>
<p class="MsoNormal">Please share if you have any thoughts.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks a lot for your support,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Nir.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Etherlab-users <etherlab-users-bounces@etherlab.org>
<b>On Behalf Of </b>Geller, Nir<br>
<b>Sent:</b> Sunday, April 25, 2021 4:00 PM<br>
<b>To:</b> Gavin Lambert <gavin.lambert@tomra.com>; Richard Hacker <ha@igh.de>; etherlab-users@etherlab.org<br>
<b>Subject:</b> Re: [Etherlab-users] Running a large number of slaves<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Hi Gavin,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for your reply.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The final system I am developing will run about 80 slaves, each with a PDO domain size of ~130 bytes.<o:p></o:p></p>
<p class="MsoNormal">I do not have such a number of slaves at my disposal, so I’m trying to somehow simulate a PDO domain that exceeds 1486 bytes in order to test the ecat master.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I created 2 slaves, each with a PDO domain of about 920 bytes.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I also asked myself how the data will be split between the ethernet frames.<o:p></o:p></p>
<p class="MsoNormal">(Both slaves support overlapping PDOs).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I expected that 2 LRW datagrams will be created, each carrying the PDO data intended for a specific slave and sent in a separate ethernet frame. Why should this be a problem?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The situation is that only 1 LRW datagram is created, in the size of 1830 bytes.<o:p></o:p></p>
<p class="MsoNormal">This, of course, is not going to work.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In datagram.c, ec_domain_finish(), <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The if statement<o:p></o:p></p>
<p class="MsoNormal">if (fmmu->logical_domain_offset + fmmu->data_size - datagram_offset > EC_MAX_DATA_SIZE) {<o:p></o:p></p>
<p class="MsoNormal">is never executed, but<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">/* Allocate last datagram pair, if data are left (this is also the case if<o:p></o:p></p>
<p class="MsoNormal"> * the process data fit into a single datagram) */<o:p></o:p></p>
<p class="MsoNormal">if (domain->data_size > datagram_offset) {<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is executed only once.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Could you direct me more precisely where in the code a fix should be implemented?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Nir.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Gavin Lambert <<a href="mailto:gavin.lambert@tomra.com">gavin.lambert@tomra.com</a>>
<br>
<b>Sent:</b> Friday, April 23, 2021 1:13 AM<br>
<b>To:</b> Geller, Nir <<a href="mailto:nir.geller@servotronix.com">nir.geller@servotronix.com</a>>; Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>;
<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a><br>
<b>Subject:</b> RE: [Etherlab-users] Running a large number of slaves<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The EtherCAT bus in general is not designed for that kind of thing. When you have a large PDO domain, it is supposed to be because you have a large number of smaller slaves, not a small number of large slaves.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’m not sure exactly where the cutoff should be, but most likely any single slave wanting to exchange more than 300 bytes or so should probably be using SDO rather than PDO. (SDO mailboxes can be configured up to 1484 bytes, although that
depends on slave implementation too and most only support a much smaller size.) Do you really need that amount of data each and every cycle?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">The packet-splitting does work – I have systems where each cycle sends three PDO packets – but the largest amount of PDO data in any one slave in my network is about 200 bytes. Most slaves are a lot less.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p><strong><span style="font-family:"Calibri",sans-serif;color:#595959">Gavin Lambert</span></strong><b><span style="color:#595959"><br>
</span></b><span style="color:#595959">Senior Software Developer<o:p></o:p></span></p>
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<p class="MsoNormal"><b>From:</b> Geller, Nir <<a href="mailto:nir.geller@servotronix.com">nir.geller@servotronix.com</a>>
<br>
<b>Sent:</b> Friday, 23 April 2021 1:39 am<br>
<b>To:</b> Geller, Nir <<a href="mailto:nir.geller@servotronix.com">nir.geller@servotronix.com</a>>; Gavin Lambert <<a href="mailto:gavin.lambert@tomra.com">gavin.lambert@tomra.com</a>>; Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>;
<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a><br>
<b>Subject:</b> RE: [Etherlab-users] Running a large number of slaves<o:p></o:p></p>
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<p class="MsoNormal"><span style="color:white">Hi,</span><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">In my setup I have 2 ecat slaves with a large PDO data worth of 917 bytes.<o:p></o:p></p>
<p class="MsoNormal">A LRW datagram is allocated with a payload size of 1830 bytes:<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">[ 56.206673] EtherCAT DEBUG 0: Adding datagram pair with expected WC 6.<o:p></o:p></p>
<p class="MsoNormal">[ 56.206690] EtherCAT 0: Domain0: Logical address 0x00000000, 1830 byte, expected working counter 6.<o:p></o:p></p>
<p class="MsoNormal">[ 56.215738] EtherCAT 0: Datagram domain0-0-main: Logical offset 0x00000000, 1830 byte, type LRW at f1c6600c.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">My suspicion is that in master.c, ec_master_send_datagrams(), the following piece of code<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"> // does the current datagram fit in the frame?<o:p></o:p></p>
<p class="MsoNormal"> datagram_size = EC_DATAGRAM_HEADER_SIZE + datagram->data_size<o:p></o:p></p>
<p class="MsoNormal"> + EC_DATAGRAM_FOOTER_SIZE;<o:p></o:p></p>
<p class="MsoNormal"> if (cur_data - frame_data + datagram_size > ETH_DATA_LEN) {<o:p></o:p></p>
<p class="MsoNormal"> more_datagrams_waiting = 1;<o:p></o:p></p>
<p class="MsoNormal"> break;<o:p></o:p></p>
<p class="MsoNormal"> }<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Gets stuck in an infinite loop because it can’t handle a datagram larger than 1500 bytes.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Is my assumption correct?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Do you happen to have a code fix for this situation?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Nir.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><b>From:</b> Etherlab-users <<a href="mailto:etherlab-users-bounces@etherlab.org">etherlab-users-bounces@etherlab.org</a>>
<b>On Behalf Of </b>Geller, Nir<br>
<b>Sent:</b> Wednesday, April 21, 2021 11:10 AM<br>
<b>To:</b> Gavin Lambert <<a href="mailto:gavin.lambert@tomra.com">gavin.lambert@tomra.com</a>>; Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>;
<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a><br>
<b>Subject:</b> Re: [Etherlab-users] Running a large number of slaves<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Hello again,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I tried running the ethercat master with a large PDO domain, but with no success.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Following<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><a href="https://eur02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsourceforge.net%2Fu%2Fuecasm%2Fetherlab-patches%2Fci%2Fdefault%2Ftree%2F%23readme&data=04%7C01%7Cgavin.lambert%40tomra.com%7C69c3c87304b241e33b3108d905940454%7C4308d118edd143008a37cfeba8ad5898%7C0%7C0%7C637546955571855490%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=zPIH9KoPnpog%2BVGlqXG2mJ58VWV72Z%2FjzcmO3Uv2dvY%3D&reserved=0">https://sourceforge.net/u/uecasm/etherlab-patches/ci/default/tree/#readme</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I built the ethercat master with Gavin's patch set.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">I'm running on a x86 Intel Atom dual core with linux kernel 3.18.48. Ethernet adapter is igb.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">To achieve a very large PDO volume I created 2 ecat slaves, each with PDO data worth of 917 bytes.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">When connecting only 1 slave, and running examples/user/ec_user_example I can raise the slave to OP and exchange data between the master and slave over PDO.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">When connecting 2 slaves the start up process of the ethercat master gets stuck after<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">EtherCAT DEBUG 0-main-0: Checking system time offset.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">And according to a wireshark capture the communication completely stops even though the application is still running cyclically.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Can you please help me setup a functional system?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Thanks,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;color:black">Nir.<o:p></o:p></span></p>
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<div id="divRplyFwdMsg">
<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Etherlab-users <<a href="mailto:etherlab-users-bounces@etherlab.org">etherlab-users-bounces@etherlab.org</a>> on behalf of Geller, Nir <<a href="mailto:nir.geller@servotronix.com">nir.geller@servotronix.com</a>><br>
<b>Sent:</b> Wednesday, March 31, 2021 1:48 PM<br>
<b>To:</b> Gavin Lambert <<a href="mailto:gavin.lambert@tomra.com">gavin.lambert@tomra.com</a>>; Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>;
<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a> <<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a>><br>
<b>Subject:</b> Re: [Etherlab-users] Running a large number of slaves</span> <o:p>
</o:p></p>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
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<div>
<p class="MsoNormal">Hi Gavin,<br>
<br>
This sounds promising.<br>
<br>
With regard to cyclic real time performance, does fragmentation work properly and efficiently with slaves that support DC?<br>
<br>
Thanks,<br>
<br>
Nir.<br>
<br>
-----Original Message-----<br>
From: Gavin Lambert <<a href="mailto:gavin.lambert@tomra.com">gavin.lambert@tomra.com</a>>
<br>
Sent: Tuesday, March 30, 2021 9:40 AM<br>
To: Geller, Nir <<a href="mailto:nir.geller@servotronix.com">nir.geller@servotronix.com</a>>; Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>;
<a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a><br>
Subject: RE: [Etherlab-users] Running a large number of slaves<br>
<br>
Yes, it splits to multiple packets automatically. Just be careful to not use more data than your cycle rate will allow.<br>
<br>
Note that initialization and configuration of a large number of slaves is very slow by default, as it occurs in series.<br>
The unofficial patchset changes this to occur in parallel (for groups at a time rather than the whole network, to avoid creating too many packets at once).<br>
<br>
<br>
Gavin Lambert<br>
Senior Software Developer<br>
<br>
<br>
<br>
<br>
COMPAC SORTING EQUIPMENT LTD | 4 Henderson Pl | Onehunga | Auckland 1061 | New Zealand<br>
Switchboard: +49 2630 96520 | <a href="https://www.tomra.com">https://www.tomra.com</a><br>
<br>
The information contained in this communication and any attachment is confidential and may be legally privileged. It should only be read by the person(s) to whom it is addressed. If you have received this communication in error, please notify the sender and
delete the communication.<br>
-----Original Message-----<br>
From: Geller, Nir<br>
Sent: Tuesday, 30 March 2021 1:23 am<br>
To: Richard Hacker <<a href="mailto:ha@igh.de">ha@igh.de</a>>; <a href="mailto:etherlab-users@etherlab.org">
etherlab-users@etherlab.org</a><br>
Subject: Re: [Etherlab-users] Running a large number of slaves<br>
<br>
Hi,<br>
<br>
Thanks for your reply.<br>
<br>
You mean that in the case of a large amount of PDO data ( > 1500), a single invoke of ecrt_master_send(master) will result several frames sent out 1 after another?<br>
<br>
Nir.<br>
<br>
-----Original Message-----<br>
From: Etherlab-users <<a href="mailto:etherlab-users-bounces@etherlab.org">etherlab-users-bounces@etherlab.org</a>> On Behalf Of Richard Hacker<br>
Sent: Monday, March 29, 2021 3:09 PM<br>
To: <a href="mailto:etherlab-users@etherlab.org">etherlab-users@etherlab.org</a><br>
Subject: Re: [Etherlab-users] Running a large number of slaves<br>
<br>
EtherCAT and the master are not limited to the ethernet packet size.<br>
EtherCAT frames are automatically divided into smaller ethernet packets as required. As long as you're not exceeding physical limits, (like sending ~1,5kb at a rate of 1kHz), you should be fine.<br>
<br>
Physically EtherCAT can address ~64k slaves on a network.<br>
<br>
On 2021-03-29 13:22, Geller, Nir wrote:<br>
> Hi There,<br>
><br>
> I'm trying to setup one ethercat master with a very large number of <br>
> ethercat slaves.<br>
><br>
> The first obstacle I'm thinking about is a very large amount of data <br>
> sent over PDO each cycle, that will definitely exceed 1500 bytes.<br>
><br>
> In order to address this issue I want to understand if it is possible <br>
> to send more than one frame each cycle?<br>
><br>
> Another method could be using jumbo frames. Does the ethercat master <br>
> support that?<br>
><br>
> Does anybody have practical experience with such a setup?<br>
><br>
> Thanks,<br>
><br>
> Nir.<br>
><br>
><br>
<br>
Mit freundlichem Gruß<br>
<br>
Richard Hacker<br>
<br>
--<br>
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