Dynomotion

Group: DynoMotion Message: 8131 From: easydigisoft Date: 8/20/2013
Subject: KFLOP restarts itself
OK this is new problem. When I switch some big pumps like hydraulics or Z brake over 12 V relays, SOMETIMES my KFLOP restarts itself and I lose connection the the PC. I think it happens some sort of disturbance in the power.

so here is the question.

1. Should the power supply (used for powering KFLOP) GND be connected to whole machine ground (chassis). Right now it is connected like that.

2. Can I have this problem because my relays do not use isolated PSU but they use the same PSU that is used by KFLOP.


THANK YOU.
Group: DynoMotion Message: 8132 From: carlcnc Date: 8/20/2013
Subject: Re: KFLOP restarts itself
Run a ground from machine frame to your building ground
should solve the problem
any low voltage, low current signal [ie usb] is easily
overrun by spikes when a large relay/contactor opens,
or by a sudden surge when a heavy load is introduced
Electrons are EVIL and will screw with us anyway they can lol

also, are you using a usb hub or connected direct from kflop to pc?
suggest the latter


--- In DynoMotion@yahoogroups.com, "easydigisoft" <easydigisoft@...> wrote:
>
> OK this is new problem. When I switch some big pumps like hydraulics or Z brake over 12 V relays, SOMETIMES my KFLOP restarts itself and I lose connection the the PC. I think it happens some sort of disturbance in the power.
>
> so here is the question.
>
> 1. Should the power supply (used for powering KFLOP) GND be connected to whole machine ground (chassis). Right now it is connected like that.
>
> 2. Can I have this problem because my relays do not use isolated PSU but they use the same PSU that is used by KFLOP.
>
>
> THANK YOU.
>
Group: DynoMotion Message: 8133 From: Tom Kerekes Date: 8/20/2013
Subject: Re: KFLOP restarts itself
Hi easydigisoft,

You should not connect KFLOP DC GND to earth ground.

Do you have a Kanalog?  Make sure you have reverse diodes connected across any relay coils.  A separate power supply may help but should not be absolutely necessary.

Regards
TK


Group: DynoMotion Message: 8135 From: Michael Rosenfield Date: 8/20/2013
Subject: Re: KFLOP restarts itself
Thing is that if the KFlop is connected to a PC with USB cable, the ground on the USB will be PC ground, which is also tied to earth ground thru the PC power supply.
Michael Rosenfield
 
Group: DynoMotion Message: 8136 From: Tom Kerekes Date: 8/20/2013
Subject: Re: KFLOP restarts itself
Hi Michael,

That is true (assuming no USB isolator).  But making another connection from KFLOP to earth ground creates a Ground loop which forms a path where earth ground currents can now flow through KFLOP and the USB cable to get to earth ground.

It isn't always this simple but see the attached diagram for the basic idea.

Regards
TK

From: Michael Rosenfield <mrosenfield@...>
To: "DynoMotion@yahoogroups.com" <dynomotion@yahoogroups.com>
Sent: Tuesday, August 20, 2013 6:04 PM
Subject: RE: [DynoMotion] KFLOP restarts itself

 
Thing is that if the KFlop is connected to a PC with USB cable, the ground on the USB will be PC ground, which is also tied to earth ground thru the PC power supply.
Michael Rosenfield
 
Group: DynoMotion Message: 8138 From: morgtod Date: 8/21/2013
Subject: Re: KFLOP restarts itself
I've read that USB is very susceptible to noise, are there any ways to make USB more stable? Like, differential drivers, isolators, ferrites, shields, shorter cables, different grade of USB cable?

Todd





--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Michael,
>
> That is true (assuming no USB isolator).  But making another connection from KFLOP to earth ground creates a Ground loop which forms a path where earth ground currents can now flow through KFLOP and the USB cable to get to earth ground.
>
> It isn't always this simple but see the attached diagram for the basic idea.
>
> Regards
> TK
>
>
>
> ________________________________
> From: Michael Rosenfield <mrosenfield@...>
> To: "DynoMotion@yahoogroups.com" <dynomotion@yahoogroups.com>
> Sent: Tuesday, August 20, 2013 6:04 PM
> Subject: RE: [DynoMotion] KFLOP restarts itself
>
>
>
>  
> Thing is that if the KFlop is connected to a PC with USB cable, the ground on the USB will be PC ground, which is also tied to earth ground thru the PC power supply.
> Michael Rosenfield
>  
>
>
> ________________________________
> To: DynoMotion@yahoogroups.com
> From: tk@...
> Date: Tue, 20 Aug 2013 14:22:19 -0700
> Subject: Re: [DynoMotion] KFLOP restarts itself
>
>  
> Hi easydigisoft,
>
> You should not connect KFLOP DC GND to earth ground.
>
> Do you have a Kanalog?  Make sure you have reverse diodes connected across any relay coils.  A separate power supply may help but should not be absolutely necessary.
>
>
> Regards
> TK
>
>
>
>
> ________________________________
> From: easydigisoft <easydigisoft@...>
> To: DynoMotion@yahoogroups.com
> Sent: Tuesday, August 20, 2013 2:07 PM
> Subject: [DynoMotion] KFLOP restarts itself
>
>
>
>  
> OK this is new problem. When I switch some big pumps like hydraulics or Z brake over 12 V relays, SOMETIMES my KFLOP restarts itself and I lose connection the the PC. I think it happens some sort of disturbance in the power.
>
> so here is the question.
>
> 1. Should the power supply (used for powering KFLOP) GND be connected to whole machine ground (chassis). Right now it is connected like that.
>
> 2. Can I have this problem because my relays do not use isolated PSU but they use the same PSU that is used by KFLOP.
>
> THANK YOU.
>
Group: DynoMotion Message: 8139 From: Michael Rosenfield Date: 8/21/2013
Subject: Re: KFLOP restarts itself
There are USB isolators out there; they will keep the KFlop ground separate from the PC ground. They optically isolate all the signals, as well as power and ground. I bought one for about $30; I am not actually using it because I'm not having noise issues. My machine is in a light-industrial area, so the biggest machines are a bunch of 5 HP air compressors.
Michael
 
Group: DynoMotion Message: 8141 From: Michael Rosenfield Date: 8/22/2013
Subject: Re: KFLOP restarts itself [1 Attachment]
Excellent point, Tom.
Thanks for the reminder!
Michael