Re: My device stops receiving when powered from battery
FLJ <[email protected]> Thu, 27 Sep 2018 13:51:00 +0200
| Newsgroups | gmane.comp.hardware.bus.can |
|---|---|
| Message-ID | <CAOsOv4=FYNVH-Bn9xq1oviLPY7bEWm41nrmvNivDvZwgVQTs0g@mail.gmail.com> |
--000000000000127cd90576d8f6cb Content-Type: text/plain; charset="UTF-8" Regarding the battery, it can definitely supply enough power to all 4 CAN nodes (this includes my device), because the working system is built to drive an electric motor as well. The battery could power the 4 nodes for hours if not days, since we are not powering the motor until the issue with the CAN is figured out. We are not adding any additional consumers. My device is a CAN logger, there is wiring in the system (CAN connector) for this purpose. We are provided only with CAN-H and CAN-L. For my understanding a common ground is ensured, since all nodes are powered by the same battery. On Thu, Sep 27, 2018 at 1:35 PM Christiano SA <[email protected]> wrote: > At some point the battery would fail. > It would not be normal to plug infinite nodes into the system without > causing a side effect. Every battery has a max current. > > The external power worked because CAN Bus signal is differential (A-B) as > well as RS-485 is also. > I already saw in a book (Jan Axelson) saying that on RS-485 the common GND > must be next to the signals. In OBD-II interface, I see that the GND goes > along too. > But I have already tested a RS-485 system without common GND and it > worked, I do not know exactly how, it must have some protection mechanism > that automatically balances the commons. > > > > Sent: Thursday, September 27, 2018 at 7:09 AM > > From: FLJ <[email protected]> > > To: [email protected] > > Subject: [CANLIST] My device stops receiving when powered from battery > > > > Hello everyone, > > > > as a software developer I'm completely perplexed by my current problem. I > > only have basic HW knowledge and I mostly follow HW diagrams designed by > > others. Until now I guess I was lucky. > > > > I have an embedded device built upon an STM32 F4 evaluation board and I'm > > using a SN65HVD230 CAN tranceiver from texas instruments with it. > > > > I have a battery powered system consisting of 3 CAN nodes using NXP > TJ1051 > > tranceivers, I don't have much detail about the MCUs used. > > > > The system all alone communicates over CAN correctly as expected. > > > > If I connect my device to the system's bus, while I power my device from > an > > external power supply, everything works fine. I receive all the CAN > > messages I want to from the systems nodes. > > My device is configured in silent mode, I don't want to send anything. > > > > As soon as I power my device from the same battery as the system, I stop > > receiving CAN messages. My device itself is working when powered from the > > common battery, meaning I can connect with the debugger to it, set > > breakpoints, etc.; only the CAN stops working. > > > > I've read a lot about common-mode voltage in the past few hours, and > about > > splitted termination, but I can't understand what the problem is. I > > would've rather expected or understood if the device wasn't working when > > powered externally, but everything on the same battery should've worked. > > > > Can anyone help me out please? > > > -- > Archives and useful links: http://groups.yahoo.com/group/CANbus > Subscribe and unsubscribe at www.vector.com/canlist/ > Report any problems to <[email protected]> > --000000000000127cd90576d8f6cb Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable <div dir=3D"ltr">Regarding the battery, it can definitely supply enough pow= er to all 4 CAN nodes (this includes my device), because the working system= is built to drive an electric motor as well. The battery could power the 4= nodes for hours if not days, since we are not powering the motor until the= issue with the CAN is figured out. We are not adding any additional consum= ers.<div><br></div><div>My device is a CAN logger, there is wiring in the s= ystem (CAN connector) for this purpose. We are provided only with CAN-H and= CAN-L. For my understanding a common ground is ensured, since all nodes ar= e powered by the same battery.</div><div><br><div><br></div><div><br></div>= </div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr">On Thu, Sep 27,= 2018 at 1:35 PM Christiano SA <<a href=3D"mailto:[email protected]= m">[email protected]</a>> wrote:<br></div><blockquote class=3D"gma= il_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-lef= t:1ex">At some point the battery would fail. <br> It would not be normal to plug infinite nodes into the system without causi= ng a side effect. Every battery has a max current.<br> <br> The external power worked because CAN Bus signal is differential (A-B) as w= ell as RS-485 is also.<br> I already saw in a book (Jan Axelson) saying that on RS-485 the common GND = must be next to the signals. In OBD-II interface, I see that the GND goes a= long too.<br> But I have already tested a RS-485 system without common GND and it worked,= I do not know exactly how, it must have some protection mechanism that aut= omatically balances the commons. <br> <br> <br> > Sent: Thursday, September 27, 2018 at 7:09 AM<br> > From: FLJ <<a href=3D"mailto:[email protected]" target=3D"_blank">= [email protected]</a>><br> > To: <a href=3D"mailto:[email protected]" target=3D"_blank">canlist@c= anlist.org</a><br> > Subject: [CANLIST] My device stops receiving when powered from battery= <br> ><br> > Hello everyone,<br> > <br> > as a software developer I'm completely perplexed by my current pro= blem. I<br> > only have basic HW knowledge and I mostly follow HW diagrams designed = by<br> > others. Until now I guess I was lucky.<br> > <br> > I have an embedded device built upon an STM32 F4 evaluation board and = I'm<br> > using a SN65HVD230 CAN tranceiver from texas instruments with it.<br> > <br> > I have a battery powered system consisting of 3 CAN nodes using NXP TJ= 1051<br> > tranceivers, I don't have much detail about the MCUs used.<br> > <br> > The system all alone communicates over CAN correctly as expected.<br> > <br> > If I connect my device to the system's bus, while I power my devic= e from an<br> > external power supply, everything works fine. I receive all the CAN<br= > > messages I want to from the systems nodes.<br> > My device is configured in silent mode, I don't want to send anyth= ing.<br> > <br> > As soon as I power my device from the same battery as the system, I st= op<br> > receiving CAN messages. My device itself is working when powered from = the<br> > common battery, meaning I can connect with the debugger to it, set<br> > breakpoints, etc.; only the CAN stops working.<br> > <br> > I've read a lot about common-mode voltage in the past few hours, a= nd about<br> > splitted termination, but I can't understand what the problem is. = I<br> > would've rather expected or understood if the device wasn't wo= rking when<br> > powered externally, but everything on the same battery should've w= orked.<br> > <br> > Can anyone help me out please?<br> > <br> --<br> Archives and useful links: <a href=3D"http://groups.yahoo.com/group/CANbus"= rel=3D"noreferrer" target=3D"_blank">http://groups.yahoo.com/group/CANbus<= /a><br> Subscribe and unsubscribe at <a href=3D"http://www.vector.com/canlist/" rel= =3D"noreferrer" target=3D"_blank">www.vector.com/canlist/</a><br> Report any problems to <<a href=3D"mailto:canlist-owner@vector-informati= k.de" target=3D"_blank">[email protected]</a>><br> </blockquote></div> --000000000000127cd90576d8f6cb-- -- Archives and useful links: http://groups.yahoo.com/group/CANbus Subscribe and unsubscribe at www.vector.com/canlist/ Report any problems to <[email protected]>