Dynomotion

Group: DynoMotion Message: 10163 From: swarbrick_jon Date: 9/10/2014
Subject: 24V -> LVTTL

Tom,


I am very keen to connect a couple of inductive proximity sensors http://www.automationdirect.com/static/specs/prox8mmae.pdf  to AB quadratic encoder inputs.  They operate at 30Khz which is significantly more than I need with 6 counts per revolution and less than 3000RPM spindle.


I am running them from a 24V source and I do not want to harm my KAnalog / Kflop boards so I thought I would check with you first.


The actual output is less than 24V but if we presume it is 24 then: would a 3KOhm resistor resulting in 3.25V across the 470Ohm that is across the inputs make this safe for the Dynomotion boards?


Is there a specific voltage I should be aiming for?


I cant see a current limit recommended by you so based on search I have found 10mA recommended for some LVTTL and my sums give this above.  Please advise.


Eagerly waiting to thread...


Jon
Group: DynoMotion Message: 10164 From: swarbrick_jon Date: 9/10/2014
Subject: Re: 24V -> LVTTL

I have these working as limit switches so I guess another option would be to map-copy the OI inputs over to the AB channels in a C program, unfortunately I am likely going to be busy till you get back online but I will see if I can do it that way :)


Jon.
Group: DynoMotion Message: 10165 From: TK Date: 9/10/2014
Subject: Re: 24V -> LVTTL
Hi Jon,

I don't see where it says they operate up to 30KHz. I see time delay of 5 or 100 milliseconds which would be much slower. 

Is that 6 cycles per rev?  Which would be 24 transitions?

3000/60 x 24 = 1200 transitions/sec

But yes if you divide the voltage down to 3.25V there should be no problem. You would need to add the external resistors. The KFLOP inputs are basically voltage sensitive (meg ohms) and require virtually no power.   JP4 and JP6 have 150ohm pull down resistors that may be helpful. 

Or using the Opto inputs you could copy them to I driven hardware encoder IO bits with a C Program (as you described).  Or just count the transitions in software like the MPGSmooth.c example does. 

Regards
TK

On Sep 10, 2014, at 1:51 AM, "jswarbrick@... [DynoMotion]" <DynoMotion@yahoogroups.com> wrote:

 

Tom,


I am very keen to connect a couple of inductive proximity sensors http://www.automationdirect.com/static/specs/prox8mmae.pdf  to AB quadratic encoder inputs.  They operate at 30Khz which is significantly more than I need with 6 counts per revolution and less than 3000RPM spindle.


I am running them from a 24V source and I do not want to harm my KAnalog / Kflop boards so I thought I would check with you first.


The actual output is less than 24V but if we presume it is 24 then: would a 3KOhm resistor resulting in 3.25V across the 470Ohm that is across the inputs make this safe for the Dynomotion boards?


Is there a specific voltage I should be aiming for?


I cant see a current limit recommended by you so based on search I have found 10mA recommended for some LVTTL and my sums give this above.  Please advise.


Eagerly waiting to thread...


Jon