Acceleration, Steps change and maximum program size

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Tyler Clanders

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Jun 7, 2017, 12:33:32 PM6/7/17
to Velmex Controls
So I need to do more than just a linear acceleration profile to a maximum velocity.

I have found that it is possible to input multiple commands to change acceleration and velocity ect after first # of steps is completed. So my thought is to break up my curved acceleration profile into multiple linear accelerations to make up my curve for example:

NOTE: I have left out start/end/clear communication commands for easier reading
A 2, S 0.1, I 1000, A 2.2, S 0.4,I 1000

My question is if the above sample code could accelerate continuously without stutters in between sections? Assuming the segments join together well in more or less slight deviations in slope. The above code is just a off the top of my head example that mot likely will not follow that criteria very well. 

Lastly I was curious about the size of program I can send through the terminal through labview or COSMOS. The manual says each program can hold 256 bytes of info but is that the same as the terminal? Is the terminal just posting the program into slot 1 memory and replacing after each clear? 

If this is the case and my assumption of discrete lines works well that would mean if I were to break each of my lines into a set of (I , S , A) commands my maximum amount of lines would be:

( 256 Bytes) / ((3 bytes/variable) ( 3 variables / command)) = 28 commands  OR  256/9 = 28 commands   -- correct?

Thank you for any help you may provide
-Tyler Scofield

Velmex Support

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Jun 7, 2017, 4:18:39 PM6/7/17
to velmex-...@googlegroups.com
On 6/7/2017 12:33 PM, Tyler Clanders wrote:
So I need to do more than just a linear acceleration profile to a maximum velocity.

I have found that it is possible to input multiple commands to change acceleration and velocity ect after first # of steps is completed. So my thought is to break up my curved acceleration profile into multiple linear accelerations to make up my curve for example:

NOTE: I have left out start/end/clear communication commands for easier reading
A 2, S 0.1, I 1000, A 2.2, S 0.4,I 1000

My question is if the above sample code could accelerate continuously without stutters in between sections? Assuming the segments join together well in more or less slight deviations in slope. The above code is just a off the top of my head example that mot likely will not follow that criteria very well. 
The basic concept is pretty much on target, but to get the movements to be smooth without stutters, the commands will need to be wrapped in a continuous index (VXM Users Manual P14)

Lastly I was curious about the size of program I can send through the terminal through labview or COSMOS. The manual says each program can hold 256 bytes of info but is that the same as the terminal? Is the terminal just posting the program into slot 1 memory and replacing after each clear?
The terminal is posting in slot 1 and clearing (or overwriting) on each send.


If this is the case and my assumption of discrete lines works well that would mean if I were to break each of my lines into a set of (I , S , A) commands my maximum amount of lines would be:
A = 2 bytes
S = 3 bytes
I = 4bytes

( 256 Bytes) / ((3 bytes/variable) ( 3 variables / command)) = 28 commands  OR  256/9 = 28 commands   -- correct?

Thank you for any help you may provide
-Tyler Scofield

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Tyler Clanders

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Jun 7, 2017, 6:36:20 PM6/7/17
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Hey Cliff, thanks for the prompt response.

I thought the continuous indexing functionality is used to get "pulses" for output at specified locations?

Also after further reading the manual it looks as if acceleration must remain constant during this continous indeixing but velocity can be changed in between indexes as can be referenced here:

page 40

c) The acceleration value set before the “U7” command will be used in the continuous index.

page 48 

As mentioned in Appendix D, speed commands can be used between indexes in the continuous index mode. The number of speed changes is limited only by available program memory space. Changes in speed will occur at the acceleration rate set before the continuous index mode.

 If I am mistaken could you please write a small sample of how it would be done? thanks.

Velmex Support

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Jun 8, 2017, 1:58:36 PM6/8/17
to Tyler Clanders, Velmex Controls, Manny Freshman
Tyler,
You are correct (see attached for a "rough ramp")
On 6/7/2017 6:36 PM, Tyler Clanders wrote:
Hey Cliff, thanks for the prompt response.

I though the continuous indexing functionality is used to get "pulses" for output at specified locations?

Also after further reading the manual it looks as if acceleration must remain constant during this continous indeixing but velocity can be changed in between indexes as can be referenced here:

page 40

c) The acceleration value set before the “ ” command will be used in the continuous index.
Virtual_Ramp_assist.txt
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