Pulse Train to Quadrature

M

Thread Starter

M Brugman

I'm using the PTO of a AB Micrologix PLC as the master encoder signal to slave a couple of 1-1/2 axis servo drives to. The pulse frequency from the PLC can be up to 20KHz.

I'm looking for a (preferably small, DIN-rail mount) signal conditioner/converter to take that single 24V pulse train and output a differential quadrature encoder-type signal (at TTL levels).

I've found some things that are close, but not quite what I'm looking for. Anyone else ever use somthing like this?

Thanks,
Matt
 
R

Robert Scott

Quadrature encoders encoder direction as well as counts, but your pulse train is inherently unidirectional. Are you looking for something that assumes one direction and generates quadrature in that direction? Or do you have two pulse trains, one for UP and the other for DOWN? Or do you have a separate direction signal that can be used to condition the encoder to count in the specified direction?

Robert Scott
Real-Time Specialties
Embedded System Consulting
 
One direction is all I need. A direction input could be there, but I don't need it in this application. Kinda like going from step-and-direction to quadrature.

Matt
 
You'll probably have to build your own in a DIN Rail box. All you need is a level shifter from 24V to 5V for the clock (a transistor and a few resistors), two flip flops to convert the pulses into quadrature format (really a two bit Gray Code, Sa=Not Qb, Sb = Qa), and two RS-422 line drivers.
 
R

Robert Scott

Then what you want is essentially a stepper motor translator, set up for full stepping. That is exactly what they do. The A and B motor drive signals are quadrature signals. The question is, can you find one that is in a small enough package for you. Most stepper motor translators come packaged with power drive electronics that you do not need and which takes up space.

Robert Scott
Real-Time Specialties
Embedded Systems Consulting
 
D
Hi,

I've required the same "pulse to quadrature" device for several applications - unidirectional. We have built a small device for this function. It is the same device as some of your other replies - i.e.: opto isolated level converter, dual FF, dual differential line driver. If you are still searching - email back to me.

Thanks,
Dan Becker
[email protected]
 
Top