Originally Posted by
joeavaerage
Hi,
absolute encoders can tell exactly where they are within one rotation. Most CNC machines however require the stepper or servo turn many times,
maybe one hundred or more revolutions from one end of travel to the other. An absolute encoder won't help that much.
You may have been thinking about the very latest 'multi-turn absolute encoders'. They are still at this time a fairly rare breed, They will have 24 bit
or more, wide positions with say 8 bits dedicated to the number of complete turns from 'home' and the remaining 16 bits describing the angular
position within that one revolution. To my knowledge all of these encoders have a high speed serial interface.
I think it unlikely that you will be readily able to get one of these devices and certainly not cheaply. Even if you do you will still have to build your
own highspeed serial interface. Unless you are familiar with high speed electronic design I think its a bust.
May I suggest that you look at servos that have that capacity built in. Delta (Taiwanese, made in China) A3 series have 24bit multiturn absolute
encoders with battery backup. I believe also the DMM (Canadian, made in China) have models fitted with a 30bit multi-turn absolute.
They are not widely advertised so an email may be required to secure more info.
Craig