Single ended termination

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Hello,

Had problems getting this through, John already provided nice scope
screenshot as an example.

The purpose of the terminator is to get the end of the transmission line
look like an infinitely long line with impedance equal to the line
impedance (120ohm with CAN) and thus prevent reflections. Thus, single
terminator may be installed into one end, but the another end remains
unterminated (infinite impedance), which leads into over- and undershoots.
While the communication will pass through, the transmission line is still
broken. From practical point of view, the most significant risk is that any
other problem more will lead into total black-out. And one shall keep in
mind that the physical layer design has a direct effect on the bit error
probability, which is a basis for residual error rate, which has further
effect on the availability and safety performance of the entire system --
it is easy to violate the system requirements with a poor CAN cabling
design.

There are some reference designs (published by Daimler) in the literature
for centre termination but they cannot be recommended, because each of such
networks needs to be intentionally fine tuned. In addition to the clumsy
design, such will be a service nightmare.

My recommendation is to adopt a standard cabling and connector scheme,
where you'll find batch cables, Y- or V-branches and termination plugs,
e.g. MiniChange, M12 or Deutsch DT04/06 series.

Best regards,

Heikki Saha, CTO
  M.Sc. Automation
  Dr.Tech. Electronics
TK Engineering Oy
Hovioikeudenpuistikko 13 as 3, 65100 Vaasa
+358 (0)50 588 6894
email: [email protected]
skype: heikki.saha_tke

We are also in the 17th iCC: https://www.can-cia.org/icc

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<div dir=3D"ltr"><span style=3D"font-size:13px">Hello,</span><div><br></div=
><div>Had problems getting this through, John already provided nice scope s=
creenshot as an example.<br><div style=3D"font-size:13px"><br></div><div st=
yle=3D"font-size:13px">The purpose of the terminator is to get the end of t=
he transmission line look like an infinitely long line with impedance equal=
 to the line impedance=C2=A0(120ohm with CAN) and thus prevent reflections.=
 Thus, single terminator may be installed into one end, but the another end=
 remains unterminated (infinite impedance), which leads into over- and unde=
rshoots. While the communication will pass through, the transmission line i=
s still broken. From practical point of view, the most significant risk is =
that any other problem more will lead into total black-out. And one shall k=
eep in mind that the physical layer design has a direct effect on the bit e=
rror probability, which is a basis for residual error rate, which has furth=
er effect on the availability and safety performance of the entire system -=
- it is easy to violate the system requirements with a poor=C2=A0CAN cablin=
g design.</div><div style=3D"font-size:13px"><br></div><div style=3D"font-s=
ize:13px">There are some reference designs (published by Daimler) in the li=
terature for centre termination but they cannot be recommended, because eac=
h of such networks needs to be intentionally fine tuned. In addition to the=
 clumsy design, such will be a service nightmare.</div><div style=3D"font-s=
ize:13px"><br></div><div style=3D"font-size:13px">My recommendation is to a=
dopt a standard cabling and connector scheme, where you&#39;ll find batch c=
ables, Y- or V-branches and termination plugs, e.g. MiniChange, M12 or Deut=
sch DT04/06 series.</div><div style=3D"font-size:13px"><br></div><div style=
=3D"font-size:13px">Best regards,</div><div style=3D"font-size:13px"><br></=
div><div><div dir=3D"ltr" class=3D"gmail_signature" data-smartmail=3D"gmail=
_signature"><div dir=3D"ltr"><div><div dir=3D"ltr"><div><div dir=3D"ltr"><d=
iv><div dir=3D"ltr"><div><div dir=3D"ltr">Heikki Saha, CTO<br>
=C2=A0 M.Sc. Automation<br>
=C2=A0 Dr.Tech. Electronics<br>
TK Engineering Oy<br><font face=3D"arial, helvetica, sans-serif">Hovioikeud=
enpuistikko 13 <span style=3D"color:rgb(51,51,51);font-style:normal;font-we=
ight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transf=
orm:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,2=
55);float:none;display:inline">as 3</span><span style=3D"color:rgb(51,51,51=
);font-style:normal;font-weight:400;letter-spacing:normal;text-align:start;=
text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;bac=
kground-color:rgb(255,255,255);float:none;display:inline">, 65100 Vaasa</sp=
an></font><br>
+358 (0)50 588 6894<br>
email: <a href=3D"mailto:[email protected]" target=3D"_blank">heikki.saha@=
tke.fi</a><br>
skype: heikki.saha_tke</div><div dir=3D"ltr"><br><div>We are also in the 17=
th iCC: <a href=3D"https://www.can-cia.org/icc" target=3D"_blank">https://w=
ww.can-cia.org/icc</a><br></div></div></div></div></div></div></div></div><=
/div></div></div></div></div></div>

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