My device stops receiving when powered from battery

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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?

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<div dir=3D"ltr">Hello everyone,<div><br></div><div>as a software developer=
 I&#39;m completely perplexed by my current problem. I only have basic HW k=
nowledge and I mostly follow HW diagrams designed by others. Until now I gu=
ess I was lucky.</div><div><br></div><div>I have an embedded device built u=
pon an STM32 F4 evaluation board and I&#39;m using a SN65HVD230 CAN trancei=
ver from texas instruments with it.</div><div><br></div><div>I have a batte=
ry powered system consisting of 3 CAN nodes using NXP TJ1051 tranceivers, I=
 don&#39;t have much detail about the MCUs used.</div><div><br></div><div>T=
he system all alone communicates over CAN correctly as expected.</div><div>=
<br></div><div>If I connect my device to the system&#39;s bus, while I powe=
r my device from an external power supply, everything works fine. I receive=
 all the CAN messages I want to from the systems nodes.=C2=A0</div><div>My =
device is configured in silent mode, I don&#39;t want to send anything.</di=
v><div><br></div><div>As soon as I power my device from the same battery as=
 the system, I stop receiving CAN messages. My device itself is working whe=
n powered from the common battery, meaning I can connect with the debugger =
to it, set breakpoints, etc.; only the CAN stops working.</div><div><br></d=
iv><div>I&#39;ve read a lot about common-mode voltage in the past few hours=
, and about splitted termination, but I can&#39;t understand what the probl=
em is. I would&#39;ve rather expected or understood if the device wasn&#39;=
t working when powered externally, but everything on the same battery shoul=
d&#39;ve worked.</div><div><br></div><div>Can anyone help me out please?</d=
iv><div><br></div></div>

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