Terminating resistors - are they always needed?

[John_Ess]

EASY-NET uses CAN protocol and to prevent reflections it recommends to place 120 Ohm resistors on both ends.

What if I have a simple network of just 2 easy-800 inside the same cabinet and next to each other - do I still need to terminate both ends with resistors?
What is your experience with NOT having these terminating resistors?

[henry]

Hi John,

as far as I remember the second EASY will not be recognized. But to make your own experience why not try without resistor to see what happens and report....

Greetings.....Henry

[John_Ess]

@henry - I tried and they worked just fine... although this was just my quick observation.

So perhaps we can forget resistors if easy modules are very close to each other - yes/no?

[Urs]

From my point of view it's always the same:

As long as it works without termination resistors, nobody complains, but if the Bus will ever fail, you will be the black sheep, even if the root cause will be found somewhere else.

As long as a bus documentation asks for bus termination nobody will confirm that it works without termination.

[henry]

So perhaps we can forget resistors if easy modules are very close to each other - yes/no?

I wouldn't bet that....You should watch it over a long time....may be 100 cycles work fine and the 101st does have a dropout....what happens to your application ?
And think about...there might be a reason why EATON is suggesting this resistor and it's not being closed to the next one but where is the end of the net.

[John_Ess]

As long as a bus documentation asks for bus termination nobody will confirm that it works without termination.

Stimmt - Sinn macht

mfg, John