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JogTa equivalent for linear mode


windell747
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Hi,

 

I'm converting some of my code from using Jogs to using the linear mode. When using jogs specifying the JogTa and JogTs was easy to limit the acceleration. However with the linear mode, I have to either specify ta and td. However, this is a bit inconvenient because I really know the rate in which I want to limit the acceleration, and not the time.

 

Of course, I can calculate this based on the starting and ending velocities, but I'm just wondering if there is any way that I can specify the acceleration differently?

 

Also, is there a way to specify the maximum speed in which the linear mode speed would saturate?

 

thanks,

windell

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+1

 

For me I'd like to specify in C.S. units if possible.

 

When you are doing lots of moves with variable distances sometimes you just want the PPMAC to get there at some max accel and some speed and calculate the best and shortest trajectory. Think of a pick and place machine, its moving all over the place traversing coordinates and the accel time is going to vary all over the place depending on whether it needs a 0.100" move or a 10.000" move. Rapid mode is one way to do this [i think?] but the units are set up using the system max accel or jog accel. I'm far from a PPMAC motion expert but this is the only solution I've found so far.

 

Look up the max accel and max jog accel parameters, and rapid mode. I believe you set the system Ta parameters negative to use rate instead of time. I'd much rather have real accel and jerk command in the motion language that works with all modes, but it may not exist at this time.

 

Anyone at Delta Tau have any advise?

 

KEJR

 

Hi,

 

I'm converting some of my code from using Jogs to using the linear mode. When using jogs specifying the JogTa and JogTs was easy to limit the acceleration. However with the linear mode, I have to either specify ta and td. However, this is a bit inconvenient because I really know the rate in which I want to limit the acceleration, and not the time.

 

Of course, I can calculate this based on the starting and ending velocities, but I'm just wondering if there is any way that I can specify the acceleration differently?

 

Also, is there a way to specify the maximum speed in which the linear mode speed would saturate?

 

thanks,

windell

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As KEJR points out, the programmed rapid mode is the most similar to jog moves. It does use JogTa and JogTs for accel/decel, and it can even use JogSpeed if Motor[x].RapidSpeedSel is set to 0.

 

If you still want to use the programmed linear mode, realize that this mode uses common accel/decel times (ta, td, ts) for all axes because that is necessary for a straight-line path. However, if you set the times small, then the Motor[x].InvAmax, InvDmax, and InvJmax limits kick in and can stretch out the times (for all axes of a multi-axis move). These limits are only applied at move calculation time if Coord[x].SegMoveTime = 0 to disable segmentation. Otherwise, you would have to set up buffered lookahead to get accel limits, which I think is way beyond what you want to do.

 

The speed of a motor in a linear mode move will not be greater than Motor[x].MaxSpeed. PMAC will stretch out the (common) time for a move if this limit on any motor would be exceeded.

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