From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=BAYES_00, REPLYTO_WITHOUT_TO_CC autolearn=no autolearn_force=no version=3.4.4 Path: border2.nntp.dca1.giganews.com!nntp.giganews.com!usenet.blueworldhosting.com!feeder01.blueworldhosting.com!feeder.erje.net!eu.feeder.erje.net!fdn.fr!usenet-fr.net!gegeweb.org!aioe.org!.POSTED!not-for-mail From: "Dmitry A. Kazakov" Newsgroups: comp.lang.ada Subject: Re: silly ravenscar question Date: Tue, 24 Feb 2015 14:38:36 +0100 Organization: cbb software GmbH Message-ID: References: <8e30f54c-81c4-4861-897c-bb6c563c76e8@googlegroups.com> Reply-To: mailbox@dmitry-kazakov.de NNTP-Posting-Host: OpkKbm9QwHUq0Y4SxjI2mw.user.speranza.aioe.org Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Complaints-To: abuse@aioe.org User-Agent: 40tude_Dialog/2.0.15.1 X-Notice: Filtered by postfilter v. 0.8.2 Xref: number.nntp.giganews.com comp.lang.ada:192319 Date: 2015-02-24T14:38:36+01:00 List-Id: On Tue, 24 Feb 2015 03:11:45 -0800 (PST), jan.de.kruyf@gmail.com wrote: > On Tuesday, February 24, 2015 at 12:29:02 PM UTC+2, Dmitry A. Kazakov wrote: >> On Tue, 24 Feb 2015 01:07:31 -0800 (PST), jan.de.kruyf wrote: >> > I am aiming for 1 msec cycletime, but if it comes out at 2 I will also be > happy. Remember STM runs only at 168 Mhz. It is OK for most applications, but might be not OK for the transport layer. It depends on the protocol architecture. If you have it synchronous, chained, triggered in a way EtherCAT is, then latencies of the terminals tend to accumulate and you need much tighter cycles to come at 1ms of overall performance. If it is asynchronous, that solves a lot of issues, but becomes non-real-time. >> EtherCAT does not need special hardware. If you mean Beckhoff's piggyback, >> you don't have to use it. You can do all it does with a plain board and raw >> Ethernet. Admittedly it would be a lot of work and EtherCAT slave protocol >> (all upper levels) is a horrific mess. >> > yes I know, but then the timing advantage is virtually gone. And you are > very right about the mess. It is a mess regardless. If I ran the circus I would throw everything above the PDU level. > I sorted a Beckhoff installation with comms > issues a few years back. I was on the phone to Germany daily, but I got > send around in circles. From this supplier to that one to that one. . . . > So in the end -I- sorted it. Help from any of them was well below standard. Exactly same here. I have strong suspicion that they do not really know how it works either. It seems and feels as if different parts were designed by different people who are all gone ever since... >>> Is there any interest in the community? I am willing to put it under GPL. >> >> If that would not hinder selling the terminals to the end customers without >> exposing the sources... > > You raise an interesting point. Do I give things away then for everybody > to get rich with? . . . It depends on the target customers. Integrators of automation systems have no interest in source code. But generally, I don't think one could sell code anyway. You could sell a bundle hardware+software+service, with the software part ignored on the balance sheet. I understood your question as if somebody would be interested in an open platform to design terminals. Yes, there are some of terminals we could develop and sell to our customers - special signal generators, incremental decoders, oversampling ADC (Beckhoff's have systematic design flaw). This one http://www.secureplugandwork.de/servlet/is/10291/ could take use of such a platform. Presently it is BeagleBone. > So, did you work at all with the gnat ravenscar package for STM, Dimitry? No. Our system deploys full Ada 2005 (e.g. on a BeagleBone). I cannot imagine EtherCAT master or the middleware data distribution layer in Ravenscar. It is beyond my feeble imagination... -- Regards, Dmitry A. Kazakov http://www.dmitry-kazakov.de