Dynomotion

Group: DynoMotion Message: 10408 From: ericncn Date: 10/28/2014
Subject: connecting a differential encoder to the KFlop
I would like to make a temporary connection of a differential encoder to a KFlop.

Could I use a 26C32 chip (which I can source easily locally?)
http://docs-europe.electrocomponents.com/webdocs/0c88/0900766b80c887e3.pdf

I mean could I just wire the pins of the chip to the pins of the encoder and KFlop, or would it be necessary to add external components like resistors, capacitors... ?

(or, is there a better chip to use than the 26C32 ?  )

Thank you
EC
Group: DynoMotion Message: 10420 From: ericncn Date: 10/29/2014
Subject: Re: connecting a differential encoder to the KFlop
I am totally unable to solder wires, I'd do this experiment by placing the 26C32 on a breadboard I've bought and wire it temporarily to the other components.
I'd need some assistance in order to not break things..

You find attached the pinout of the "EXT" connector on my motor drive (it's a pass-through connector for the encoder signals) and the pinout of the 26C32.

I'd wire things like this:

EXT ___________ AM26C32
1 (CHB+) ......  6 (2A)
2 (CHB-) ......  7 (2B)
3 (CHA+) ......  2 (1A)
4 (CHA-) ......  1 (1B)
5 (IDX+) ...... 10 (3A)
6 (IDX-) ......  9 (3B)
7 (GND) .......  8 (GND), 12 (G')
8 (+5V_OUT) ... 16 (VCC),  4 (G)

AM26C32 ______ KFLOP JP7
 3 (1Y) ...... 7 (IO0)
 5 (2Y) ...... 8 (IO1)

AM26C32 ______ KFLOP JP5
11 (3Y) ...... 1 (IO36)

Now, it looks me the KFLOP is missing a ground reference for the A, B, IDX signals so I'd also add:

AM26C32 ______ KFLOP JP7
8 (GND) ...... 25 (GND) or 26 (GND)

Is this correct? I am a bit confused about the JP5 connector.
KFLOP manual says it is intended for communication over a twisted pair cable, but what other signal should I use to make the twisted pair? And, no ground?

Or, could I just forget the JP5 and wire the IDX signal to any JP7 pin? Is that software configurable?

Thank you,
EC
   @@attachment@@
Group: DynoMotion Message: 10423 From: Tom Kerekes Date: 10/29/2014
Subject: Re: connecting a differential encoder to the KFlop [2 Attachments]
Hi EC,

That all looks reasonable to me.

If you need the IDX signal it can be connect to any spare input as it is handled in software (unlike encoder inputs which are hardware devices).  So yes, you might feed the INX signal into any unused input on JP7 so you don't need to bother with using JP5.  You are correct the 8 I/O on JP5 need to be GND referenced.   In your case the AM26C32 will already have a GND reference from JP7.

Note that if this is only for a test it is possible to connect one of the differential signals to a single ended KFLOP input and just leave the other differential signal unconnected without using a differential receiver.  This is much more noise sensitive than having a differential receiver but compared to using a messy breadboard it may be no worse.

Additionally there are pre-built low cost 3rd party differential receiver modules available that you might look at.  Such as:
http://www.usdigital.com/products/interfaces/encoder/cable-drivers/ea#description

HTH
Regards
TK
 
From: "ericnc@... [DynoMotion]" <DynoMotion@yahoogroups.com>
To: DynoMotion@yahoogroups.com
Sent: Wednesday, October 29, 2014 2:50 AM
Subject: [DynoMotion] Re: connecting a differential encoder to the KFlop [2 Attachments]

 
[Attachment(s) from ericnc@... [DynoMotion] included below]
I am totally unable to solder wires, I'd do this experiment by placing the 26C32 on a breadboard I've bought and wire it temporarily to the other components.
I'd need some assistance in order to not break things..

You find attached the pinout of the "EXT" connector on my motor drive (it's a pass-through connector for the encoder signals) and the pinout of the 26C32.

I'd wire things like this:

EXT ___________ AM26C32
1 (CHB+) ......  6 (2A)
2 (CHB-) ......  7 (2B)
3 (CHA+) ......  2 (1A)
4 (CHA-) ......  1 (1B)
5 (IDX+) ...... 10 (3A)
6 (IDX-) ......  9 (3B)
7 (GND) .......  8 (GND), 12 (G')
8 (+5V_OUT) ... 16 (VCC),  4 (G)

AM26C32 ______ KFLOP JP7
 3 (1Y) ...... 7 (IO0)
 5 (2Y) ...... 8 (IO1)

AM26C32 ______ KFLOP JP5
11 (3Y) ...... 1 (IO36)

Now, it looks me the KFLOP is missing a ground reference for the A, B, IDX signals so I'd also add:

AM26C32 ______ KFLOP JP7
8 (GND) ...... 25 (GND) or 26 (GND)

Is this correct? I am a bit confused about the JP5 connector.
KFLOP manual says it is intended for communication over a twisted pair cable, but what other signal should I use to make the twisted pair? And, no ground?

Or, could I just forget the JP5 and wire the IDX signal to any JP7 pin? Is that software configurable?

Thank you,
EC
Group: DynoMotion Message: 10426 From: ericncn Date: 10/29/2014
Subject: Re: connecting a differential encoder to the KFlop [2 Attachments]
Hi TK,

thank you again. What I actually want to do is to decide if this milling machine is worth investing more money on it.  The original plan was to add a KAnalog and linear scales, but it's vibrating too much and I'm doubtful.

You mentioned that Bode Plots could be used to understand the dynamics of the system, so I would like to try have the KFlop read the encoders temporarily in the easiest and cheapest way, in order to understand if the problems of the machine could be fixed. After that I could either purchase the missing pieces of the system, or trash the whole project as well...

So, if you say the IDX signal is not needed and the differential receiver neither, even easier for me. How do I wire my encoder to the KFlop then? Like this?

EXT ___________ KFLOP JP7
1 (CHB+) ......  8 (IO1)
3 (CHA+) ......  7 (IO0)
7 (GND) .......  25 (GND) or 26 (GND)

But, is it OK to have the drive GND wired to the Kflop GND?
(This also happened in my other scheme, where the drive GND was wired to the AM26C32, and the AM26C32 GND was in turn wired to the Kflop GND.)


Regarding the US Digital differential receiver or its CNC4PC equivalent, they both cost  me nearly $80  after shipping costs and import costs. Would rather save that money for a KAnalog :-)  once I've verified that my system can be cured...

Thank you again
EC
P.S. In case it helps, here is my drive manual. The EXT connector is detailed on page 15:
http://granitedevices.fi/assets/files/vsd-e_160_manual.pdf
Group: DynoMotion Message: 10427 From: Dan W Date: 10/29/2014
Subject: Re: connecting a differential encoder to the KFlop

Eric,
I am not sure what your setup is. But looking at the drive manual I got a question that may help.  

Do you currently have encoders on your servos that are wired into your drives? I ask because your drives have an encoder signal output. So if you have an encoder signal coming in. You can use the encoder signal out on the "EXT" connector and feed that into the kflop. I think you would use the A and B out and not connect the "not A and not B or /A  and /B". 

Sent from my Verizon Wireless 4G LTE smartphone


Group: DynoMotion Message: 10429 From: ericncn Date: 10/30/2014
Subject: Re: connecting a differential encoder to the KFlop
Dan,

yes, yes, exactly. My servos already have encoders wired to the drives and the drives make the encoder signals available via the EXT connector.  I now want to wire the EXT connector to the Kflop. That's what we are discussing.

I believe that if I just wire A+ and B+ to the Kflop like you said, the Kflop won't be able to read them unless they are referenced to some ground.
I was asking if this would work:

EXT ___________ KFLOP JP7
1 (CHB+) ......  8 (IO1)
3 (CHA+) ......  7 (IO0)
7 (GND) .......  25 (GND) or 26 (GND)

The fact is, I seem to remember the Kflop GND had to be kept isolated from the rest of the system so I'm not sure this is a good idea...

EC

---In DynoMotion@yahoogroups.com, <engnerdan@...> wrote :


Eric,
I am not sure what your setup is. But looking at the drive manual I got a question that may help.  

Do you currently have encoders on your servos that are wired into your drives? I ask because your drives have an encoder signal output. So if you have an encoder signal coming in. You can use the encoder signal out on the "EXT" connector and feed that into the kflop. I think you would use the A and B out and not connect the "not A and not B or /A  and /B". 

Sent from my Verizon Wireless 4G LTE smartphone


Group: DynoMotion Message: 10430 From: Moray Cuthill Date: 10/30/2014
Subject: Re: connecting a differential encoder to the KFlop
Eric,
 
the principle surrounding grounds, is you don't end up with multiple grounds essentially connecting the same components, as that's when you risk introducing ground loops and introducing a whole new world of noise/interference pain.
 
However, given that you're only testing, I'd just connect things up directly as Tom recommends and see what happens. The worst thing likely to happen is you get a few erroneous steps/counts.
Best thing is if you wire them in, run the mill as you have been, checking for any change in behaviour that would signify something isn't right, and then provided the mill is still behaving correctly, configure to use the encoder inputs.
 
Moray

On Thu, Oct 30, 2014 at 8:07 AM, ericnc@... [DynoMotion] <DynoMotion@yahoogroups.com> wrote:
 

Dan,

yes, yes, exactly. My servos already have encoders wired to the drives and the drives make the encoder signals available via the EXT connector.  I now want to wire the EXT connector to the Kflop. That's what we are discussing.

I believe that if I just wire A+ and B+ to the Kflop like you said, the Kflop won't be able to read them unless they are referenced to some ground.
I was asking if this would work:

EXT ___________ KFLOP JP7
1 (CHB+) ......  8 (IO1)
3 (CHA+) ......  7 (IO0)
7 (GND) .......  25 (GND) or 26 (GND)

The fact is, I seem to remember the Kflop GND had to be kept isolated from the rest of the system so I'm not sure this is a good idea...

EC


---In DynoMotion@yahoogroups.com, <engnerdan@...> wrote :


Eric,
I am not sure what your setup is. But looking at the drive manual I got a question that may help.  

Do you currently have encoders on your servos that are wired into your drives? I ask because your drives have an encoder signal output. So if you have an encoder signal coming in. You can use the encoder signal out on the "EXT" connector and feed that into the kflop. I think you would use the A and B out and not connect the "not A and not B or /A  and /B". 

Sent from my Verizon Wireless 4G LTE smartphone


Group: DynoMotion Message: 10433 From: Dan Date: 10/30/2014
Subject: Re: connecting a differential encoder to the KFlop
Eric,
Yes you will need the ground, I just forgot to say that. I think you will be just fine on the ground situation. Like Moray said you don’t want multiple grounding points running to multiple places.
 
So I have not gone back to look to see if you gave a complete description of your setup. So if I get something wrong please don’t kill the messenger. I am making some inferences but this is what I think you have, below is what I am assuming you have setup.
 
Drive Side
KFLOP –(Step/Direction)—>Servo drive—>Servo Motor
 
Feedback Side
Servo Encoder—>Servo Drive—(Not connected Yet)—>KFLOP
 
If your KFLOP is positioned within 3M of the servo drives you should not need to worry about any converter chips to take the differential signal down to a single ended signal.
 
 
If this is the case, and you are struggling with the tuning. Here is my input
 
**A forewarning, I am no expert and I have not used Step/Direction with any Dynomotion products. But I have used it with other industrial controls. So if I have my info wrong I am sorry**
 
I have no idea what tuning parameters will actually work within the Kmotion program, being its step/direction. When I have used Step/Direction in the past on industrial controls there have been no PID loops, it all had to be done in the drive. So I would start with doing the tuning in your servo drive.
 
What values do your drives allow you to adjust?
 
 
Dan
 
Sent: Thursday, October 30, 2014 3:07 AM
Subject: RE: [DynoMotion] Re: connecting a differential encoder to the KFlop
 
 

Dan,

yes, yes, exactly. My servos already have encoders wired to the drives and the drives make the encoder signals available via the EXT connector.  I now want to wire the EXT connector to the Kflop. That's what we are discussing.

I believe that if I just wire A+ and B+ to the Kflop like you said, the Kflop won't be able to read them unless they are referenced to some ground.
I was asking if this would work:

EXT ___________ KFLOP JP7
1 (CHB+) ......  8 (IO1)
3 (CHA+) ......  7 (IO0)
7 (GND) .......  25 (GND) or 26 (GND)

The fact is, I seem to remember the Kflop GND had to be kept isolated from the rest of the system so I'm not sure this is a good idea...

EC


---In DynoMotion@yahoogroups.com, <engnerdan@...> wrote :

 
Eric,
I am not sure what your setup is. But looking at the drive manual I got a question that may help. 
 
Do you currently have encoders on your servos that are wired into your drives? I ask because your drives have an encoder signal output. So if you have an encoder signal coming in. You can use the encoder signal out on the "EXT" connector and feed that into the kflop. I think you would use the A and B out and not connect the "not A and not B or /A  and /B".
 
Sent from my Verizon Wireless 4G LTE smartphone


Group: DynoMotion Message: 10434 From: ericncn Date: 10/30/2014
Subject: Re: connecting a differential encoder to the KFlop
Moray,

your suggestion seems very reasonable (wire, check for anomalies, then configure the software).
I'll doo ass soon as I have a chance

Wil let you know
Thank you
EC


---In DynoMotion@yahoogroups.com, <moray.cuthill@...> wrote :

Eric,
 
the principle surrounding grounds, is you don't end up with multiple grounds essentially connecting the same components, as that's when you risk introducing ground loops and introducing a whole new world of noise/interference pain.
 
However, given that you're only testing, I'd just connect things up directly as Tom recommends and see what happens. The worst thing likely to happen is you get a few erroneous steps/counts.
Best thing is if you wire them in, run the mill as you have been, checking for any change in behaviour that would signify something isn't right, and then provided the mill is still behaving correctly, configure to use the encoder inputs.
 
Moray
Group: DynoMotion Message: 10435 From: ericncn Date: 10/30/2014
Subject: Re: connecting a differential encoder to the KFlop
Dan,

pardon me if I gave the impression I was killing the messenger :-) your input is very much appreciated.

Your assumption on my setup is exact.
I will add that the cable running from the differential encoder to the drive is shielded and ends in a heavy metal cabinet, containing all the electronics.
The Kflop is very close to the drives (both inside the cabinet), I can reach any point of the Kflop from the EXT connector in the drives, with a 12 inches jumper cable.

By the way, regarding noise etc., would it be better to run a flat ribbon cable from the drive to the Kflop, or a number of independent jumper cables?

Regarding tuning, my drives allow both PID and PIV modes and there are several parameters. Here is the tuning manual of my drives:
http://granitedevices.com/assets/files/Tuning_manual.pdf

and if you want to know more, the whole manual:
http://granitedevices.fi/assets/files/vsd-e_160_manual.pdf

I can tune the "torque controller" perfectly, but when it comes to the velocity controller I start getting vibrations and even worse with the position controller.

The whole idea would be to let the drives only act as torque controllers and let the Kflop control the PID.

However even if the wiring is successful, I can't do all this immediately because the way I've currently setup homing requires the drives to be in position mode.

In the short term I only want to have the Kflop read the encoders (while leaving the drives in step/dir and position mode) so that I can see the Bode Plots like Tom suggested.

Based on the results, we'll decide what to do next...

Thank you
EC

---In DynoMotion@yahoogroups.com, <engnerdan@...> wrote :

Eric,Yes you will need the ground, I just forgot to say that. I think you will be just fine on the ground situation. Like Moray said you don’t want multiple grounding points running to multiple places. So I have not gone back to look to see if you gave a complete description of your setup. So if I get something wrong please don’t kill the messenger. I am making some inferences but this is what I think you have, below is what I am assuming you have setup. Drive SideKFLOP –(Step/Direction)—>Servo drive—>Servo Motor Feedback SideServo Encoder—>Servo Drive—(Not connected Yet)—>KFLOP If your KFLOP is positioned within 3M of the servo drives you should not need to worry about any converter chips to take the differential signal down to a single ended signal.  If this is the case, and you are struggling with the tuning. Here is my input **A forewarning, I am no expert and I have not used Step/Direction with any Dynomotion products. But I have used it with other industrial controls. So if I have my info wrong I am sorry** I have no idea what tuning parameters will actually work within the Kmotion program, being its step/direction. When I have used Step/Direction in the past on industrial controls there have been no PID loops, it all had to be done in the drive. So I would start with doing the tuning in your servo drive. What values do your drives allow you to adjust?  
Group: DynoMotion Message: 10444 From: ericncn Date: 10/31/2014
Subject: Re: connecting a differential encoder to the KFlop
I do confirm that just wiring the A+, B+ and GND pins of the differential encoder to the A, B and GND pin in the Kflop worked smoothly for me. No problems at all and hardly one or two miscounts after minutes of simulated work (executing G-Code without a workpiece).

Thanks to all who answered
EC