Dynomotion

Group: DynoMotion Message: 14092 From: tapiolarikka Date: 11/17/2016
Subject: Konnect output dying?
Hi Tom,

My Konnect started exhibiting odd behavior today.

Turning bit 1064 off turns bit 1068 on occasionally.

These outputs drive relays that drive hydraulic valve coils.

Relays coils have diode protection and valve coils have varistors for surge suppression.

The C code should be OK as so far this setup has performed +120K work cycles without issue.

Any guess for the cause would be most welcome


Rgds,


Tapio
Group: DynoMotion Message: 14094 From: Tom Kerekes Date: 11/17/2016
Subject: Re: Konnect output dying?

Hi Tapio,

I don't really have any ideas.

What voltage and current do the relay coils require?

Have you checked the power supply for the relays?  How much does it change when turning the relays on and off?

Are you saying that the displayed state on the Digital IO Screen of Bit 1068 changes when Bit 1064 changes?  That would indicate a software problem rather than a hardware problem as all the output bit states are maintained in the software and only repeatedly sent to Konnect every 180us.  No problem on the Konnect could cause the Digital IO Screen values to change.

Regards

TK


On 11/17/2016 9:29 AM, tapio.larikka@... [DynoMotion] wrote:
 

Hi Tom,

My Konnect started exhibiting odd behavior today.

Turning bit 1064 off turns bit 1068 on occasionally.

These outputs drive relays that drive hydraulic valve coils.

Relays coils have diode protection and valve coils have varistors for surge suppression.

The C code should be OK as so far this setup has performed +120K work cycles without issue.

Any guess for the cause would be most welcome


Rgds,


Tapio
Group: DynoMotion Message: 14095 From: Tapio Larikka Date: 11/17/2016
Subject: Re: Konnect output dying?

Hi Tom,
 
The relay coils are app. 200mA each.
 
I haven't checked the the power source yet.
 
Yes, the bit states in Digital IO screen follow actual events.
 
Software problem would have been my first guess, but the fact that this occurs after some 120000 execution cycles puzzles me.
Also the code runs in machnotify.c where notify message response is simply
 
-setbit 1064 
-wait for sensor
-clearbit 1064
-wait for sensor
 
so the bit 1068 should be pretty much isolated from above, yet occasionally bit 1068 output activates as bit 1064 is deactivated.
Also the fact that this does not happen every time the code is executed is rather mind boggling.
I have V4.32 on this machine.
 
Thank for your input. I'll post back if I find some sensible cause for this. Luckily just this week I received a new set of hardware.
 
Rgds,
 
Tapio
 
 
Group: DynoMotion Message: 14097 From: Tapio Larikka Date: 11/18/2016
Subject: Re: Konnect output dying?

Hi Tom,
 
Not completely solved yet, but appears to be partially caused by failing/sticking relay and partially by a varistor not providing sufficient transient protection leading to
excessive sparking on relay opening.
 
Rgds,
Tapio