Dynomotion

Group: DynoMotion Message: 11393 From: cnc_machines Date: 4/15/2015
Subject: Connect Encoders Through Konnect
Tom,

I am wanting to use 6 stepper drivers, and am purchasing 2 KSteps to do so. I would like to run closed loop with Quadrature encoders. I am having some trouble finding locations for all of my encoders and drives.

The KSteps would be plugged in to JP7 and JP5. Is it possible to plug in 5V encoders to JP6 or JP4? All of my encoders are 5V and I am a bit concerned about 3.3V only on these connections. Would I need to buy another breakout board? Would the Konnect board inputs be suitable for encoder connections?

Any suggestions you have would be helpful, I may end up using 8 steppers, but no coordinated motion on motors 7 and 8.

Thanks,

Scott
Group: DynoMotion Message: 11394 From: Tom Kerekes Date: 4/15/2015
Subject: Re: Connect Encoders Through Konnect
Hi Scott,

The 8 Encoder inputs can be multiplexed over to KFLOP JP4 and JP6.  See the MuxEncoders.c example.

The JP4 and JP6 encoder inputs are 3.3V only inputs with 150 ohm termination.  They will be damaged if driven hard above 3.85V because they are diode clamped to the 3.3V supply.  Most 5V TTL drivers do not drive too high and if they do only very weakly.  They are only required to drive above a minimum of 2.8V to be a valid TTL high.  But unfortunately most devices do not specify a maximum high level.  I have never seen a case where this is a problem.  You might test your encoder outputs under a 150ohm load to see if they drive above 3.85V.  Or you might add a 47 ohm series resistor to be absolutely safe.

Konnect inputs are not suitable as encoder inputs.

HTH
Regards
TK

Group: DynoMotion Message: 11395 From: cnc_machines Date: 4/15/2015
Subject: Re: Connect Encoders Through Konnect
Tom,

Thanks for the reply. To ensure I understand, all I need to do is add the following line to my main program into my startup program:

{
    // Mux encoder inputs from KFLOP JP7 & JP5 to JP4 aand JP6
    FPGAW(ENC_NOISE_FILTER_ADD) = ENC_0_3_JP4 + ENC_4_7_JP6 + ENC_NOISE_FILTER_DEFAULT_VAL;
}

Once I do that, how do I know which of the pins on JP4 and JP6 are applicable to each axis?

I am using US Digital encoders, do you have any experience with this brand? I would rather not have to solder resisters onto the inputs. Sounds like the risk of frying the KFlop board is pretty minimal?



E5 Optical Kit Encoder

 
Group: DynoMotion Message: 11397 From: Tom Kerekes Date: 4/15/2015
Subject: Re: Connect Encoders Through Konnect
Hi Scott,

That encoder should connect directly with no problems.

When mux'ed the first 4 encoders (0-3) will be on the first 8 inputs (in order) of JP4 and the 2nd 4 encoders (4-7) on the first 8 inputs of JP6.

Regards
TK