Encoder wire problems

[2009]

Hi everyone i am new to the forum an i have a question about my encoders. They have (2) wires A and A_ for the channels.Is there a small chip I can use to make the connection to single input like (gecko,uhu) they say just use the positive wire but I am worried about noise? I am a little bit familiar with electrical but there must be a chip for this interface?

[keebler303]

Your encoder uses a differential line driver. You can just connect the A and B signals and leave the A_ and B_ disconnected. An industrial quality drive will have a differential receiver which will accept the differential signal to reduce noise issues.

Matt

[Al_The_Man]

If these are quadrature encoders they should have A & B if differential then they would have A, /A & B, /B the / indicate the complements.
If using an external supply for the encoder then you only need the common and the A & B, no need to connect the +v.
I misunderstood your question, if you wish to set up a receiver for differential there are a few IC's if you Google RS422.
Al.

[2009]

Thank you for the fast replies
But is it not the purpose of the inverted signal to get rid of the noise???

[keebler303]

The inverted signal is used to cancel noise. Since the wires run parallel, they should receive a similar amount of noise. A differential receiver will look at the difference between the two wires so that noise will be rejected. This is much better than the single-ended setup used on hobby grade drives but both work equally well in determining position.

Matt

[Al_The_Man]

I would recommend using the differential especially on larger gantry's, also it can make a difference when using electrically noisy machining methods, Plasma, Universal motor Router etc.
I find it strange why all drive manuf do not use differential input for the sake of a small extra cost, if any?.
Al.

[2009]

Thanks again

[Torchhead]

Interface - RS-422 - AM26C32 - TI.com

It is a quad differential receiver (low current) If your encoder is a true differential (4 wires) it can be a direct interface. If not you can match it to a 26C31 chip at the motor. The receiver can handle two differential channels and it spits out nice clean single ended signals to the drives. The trick is to put the receiver close to the drives and then you can run long unshielded cables (like UTP Cat 5) to the motor/encoder. Works really good in high noise environments.

TOMCaudle
www.CandCNC.com

[2009]

Thank you everyone for the replies exactly what I was looking for!!
Cheers,

[Al_The_Man]

What to watch when ordering is if the IC is DIP or SMT, unless you have the means to implement SMT then DIP is the easier way to go, many IC's have been phased out in their DIP form.
Also if ever just using a single encoder without the marker, the 8 pin SN75146 DIP will work.
Al.