PCI-7350 & Breakpoint & Totem pole issue

[Sokoll]

Hi All,

I'm trying to get along with the buffered breakpoint function of this board. 

I did connect an oscillocope to the trigger output properly to check if I see a Trigger.  

My problem: I see no Trigger but NIMAX says "Position breakpoint occured".

So i changed from Drive mode "open collector" to drive mode "totem pole"("Configure Breakpoint Output.flx") just to see what happens. Still no trigger on output but all 4 axes of the board get killed. 

What happens is: As soon as I choose Totem pole for breakpoint drive mode also the "Stepper Output Mode" is changed from open collector to totem pole (This I see in NIMAX under "Stepper Setting").

So actually setting my drive mode of the breakpoint output also sets the drive mode of the stepper output and this kills my axes. 

Is there a reason for that?

Is it the same for all of the 7350 boards or is there an issue with my board that can be solved by an exchange? 

Any help isappreciated!

Many thanksand best regards, 

Stefan

[Jochen]

Stefan,

could you please provide some more information?

1. Brekpoint generation does only work for closed loop (!) stepper axes and servo axes. What type are your axes?
2. Could you please provide the code that you have used for testing? Is this a shipping examples?
3. Which breakout box are you using (e. g. UMI-7774) and to which pins did you connect the scope?
4. Which version of NI-Motion are you using?

Thanks and kind regards,

Jochen Klier

National Instruments

[Sokoll]

Hi Jochen,

Thank You for the reply! 

1. Brekpoint generation does only work for closed loop (!) stepper axes and servo axes. What type are your axes?

Do You mean "does only work properly and exactly to the count" or "does only work at all"?

I definetly know that at least SINGLE breakpoint generation now works for my OPEN LOOP stepper axis on 7350 Motion controller.

As well as buffered HSC does.

2. Could you please provide the code that you have used for testing? Is this a shipping examples?

For the tests I just did use the flx functions provided in LabVIEW and little test programs I did not keep after now having a working system. 

3. Which breakout box are you using (e. g. UMI-7774) and to which pins did you connect the scope?

UMI-7774, pin 1 and - hmmmm - 4 or 5 - I'll have to check when I'm back in the lab.

But I asure it is the right ones because I now see the trigger pulse generated when hitting the breakpoint value of the encoder. 

4. Which version of NI-Motion are you using?

NI-Motion 7.7

As far as I can reconstruct the whole situation my problem was caused by several reasons:

1. NIMAX problem:

When I e.g. disable an axis in NIMAX it is automatically set to be a servo axis.

Generally, from time to time I all over sudden have an axis configured as servo which before definetly was configured to be a stepper axes.

Solution for me: Always keep an eye on the Servo/Stepper mode selection whenever I change anything in NIMAX. 

2. Problem with LabVIEW routine "Configure Breakpoint Output.flx"

When I was setting the breakpoint drive mode from open collector to totem pole then the the stepper output mode (in NIMAX, stepper settings) was set to totem pole, too. I'm not sure if this caused the 7350 MC to get "killed" but I it was killed and this is my explanation. 

3. Communication between the board and my app was interrupted by NIMAX when I tried to Initialize the board via NIMAX. 

I did end up with an Watchdog Timeout error. This was my fault and could easily be resolved by stopping my app and reinitializing the board. 

4. I didn't find the time to reconstruct the following situation: I could not change the drive mode from totem pole back to Open collector with the LabVIEW function.

However, since I did use NIMAX to a) define the signal as open Collector and Active High and b) increased the Pulse Width a bit now everything is working. I can generate a Trigger for the NIPCI-5922 to start DAQ as soon as the desired position is reached.

Best regards,

Stefan

[Jochen]

Hi Stefan,

I'm a bit confused. I'm not aware of breakpoint and HSC features working in open loop mode and our documentation doesn't say so either. But you have experienced that this is working???

Anyway. Thank you for the information. As much as I understand the issue is resolved for you, isn't it? Still I'm going to frward this thread to Motion Control R&D to have a closer look at the issue.

Jochen

[Sokoll]

Hi Jochen,

yes, HSC and Breakpoint generation works for open loop stepper axes.

Perhaps You do not remember but roughly 2 years ago You solved my problem that I had with initialization of stepper motors using the encoder index mark.

For Renishaw Encoders the pulse sometimes was too short for beeing properly recognized by the 7340 boards.

You suggested using HSC (source RTSI line[i]) in connection with Signal routing Index line to RTSI[i+1] and hardwiring pins RTSI[i] and [i+1].

This works perfectly (exactly to the count!) for years now and always was meant to work for open loop axes.

(We cannot use NI closed loop algorithms since encoder counts per revoluition may be not constant).

Best regards,

Stefan