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Over 485-interface slaves are connected as multi drop, physically daisy chain.

Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off.

So it makes termination value as 120hm if I connect 10 slaves.

If I want to make it as properly, just put 60 ohm resistor on each data Line(D+, D-)?

Master A(D+) -----(60ohm60 ohm)-----~~~

Master B(D-) -----(60ohm60 ohm)-----~~~

My guess is it can affect as like below:

60ohm60 ohm + 12ohm12 ohm(parallel connection from 10 slaves) + 60ohm60 ohm = 132ohm132 ohm

Surely, the best way is changing termination resistor, but I want to make it work simply.

Regards, Jiwon

Over 485-interface slaves are connected as multi drop, physically daisy chain.

Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off.

So it makes termination value as 120hm if I connect 10 slaves.

If I want to make it as properly, just put 60 ohm resistor on each data Line(D+, D-)?

Master A(D+) -----(60ohm)-----~~~

Master B(D-) -----(60ohm)-----~~~

My guess is it can affect as like below:

60ohm + 12ohm(parallel connection from 10 slaves) + 60ohm = 132ohm

Surely, the best way is changing termination resistor, but I want to make it work simply.

Regards, Jiwon

Over 485-interface slaves are connected as multi drop, physically daisy chain.

Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off.

So it makes termination value as 120hm if I connect 10 slaves.

If I want to make it as properly, just put 60 ohm resistor on each data Line(D+, D-)?

Master A(D+) -----(60 ohm)-----~~~

Master B(D-) -----(60 ohm)-----~~~

My guess is it can affect as like below:

60 ohm + 12 ohm(parallel connection from 10 slaves) + 60 ohm = 132 ohm

Surely, the best way is changing termination resistor, but I want to make it work simply.

Regards, Jiwon

1
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For wrong termination resistor uses

Over 485-interface slaves are connected as multi drop, physically daisy chain.

Those have built-in termination resistor, and the value is 120 ohm and no select switch for termination on/off.

So it makes termination value as 120hm if I connect 10 slaves.

If I want to make it as properly, just put 60 ohm resistor on each data Line(D+, D-)?

Master A(D+) -----(60ohm)-----~~~

Master B(D-) -----(60ohm)-----~~~

My guess is it can affect as like below:

60ohm + 12ohm(parallel connection from 10 slaves) + 60ohm = 132ohm

Surely, the best way is changing termination resistor, but I want to make it work simply.

Regards, Jiwon