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Could you try again with arc blend enable to true?

OK so the bad ini values seem to be LinuxCNC defaults (they were not specified in my ini file)
With more reasonable values set the errors are of much smaller magnitude bu there are still accel violations: 







Note that the acceleration (green) which has a constraint of 200 IPS/S sometimes obeys this constraint
(right side of screen) but sometimes ignores it (spikes toward center of screen reaching more than 1500 IPS/S)


ini file settings: 



 

 

 

PCW wrote:

These are in inches.

So my understanding would be:

So 20 IPS max Velocity
200 Max accel (~1/2g) so 1/10 second to maxvel with no jerk limit (old TP)
2000 Max jerk  so 1/10 second to full accel

Which (jerk=2000) actually sounds a bit low

I was doing some math to create paths (not real time) a little while back and on my machine with 0.5G (5000mm/s/s) a jerk of like 50000mm/s/s/s was the starting point of usefulness, and 500000 would probably be where I end up. So your 10:1 seems a logical place to start.

BUT, it shouldn't matter. Jerk should never create a following error, it should be mathematically precise, even if its comically low for real life machines.
 

Those ini values do not cause an issue with the old TP (0)

I'll check your suggestions in a bit...
 

These are in inches.

So my understanding would be:

So 20 IPS max Velocity
200 Max accel (~1/2g) so 1/10 second to maxvel with no jerk limit (old TP)
2000 Max jerk  so 1/10 second to full accel

Which (jerk=2000) actually sounds a bit low

Thank you Peter for looking at this.
I see a few issues with your ini.txt

16 float IN 1e+99 ini.traj_default_acceleration
16 float IN 0 ini.traj_default_jerk
16 float IN 1 ini.traj_default_velocity
16 float IN 1e+99 ini.traj_max_acceleration
16 float IN 0 ini.traj_max_jerk
16 float IN 1e+99 ini.traj_max_velocity


these settings seems a bit waky, if you want to have jerk control you need
ini.traj_default_jerk
and
ini.traj_max_jerk

to be more than 0
and the 1e+99 max acc and velocity, is this something people actually run with? is it something is supported without f-error on TP0 aka old TP?

Is a jerk of 2000 reasonable? What units is your config?

Hi, Apologies, did some more testing. If I start at ABS of Zero then Job axis 5mm at a time slowly (ie 100mm/min) every 3rd or 4th jog the counter will increment by .001 ie instead of reading 15.000 it will read 15.001, then if I keep joging it will then stay with the .001 until 35 then it will read 35.002.After some more testing here are my job results (jogging at 30mm/min and incr of 5mm)starts at ABS 0 G54=00->5->10->15->20->25.001->20->25.001->20->25.001->20->25.001->30.001...all .001 till 70.002jogging -ve from 70.002->65.001 ...all .001 til 25.000 .. all the way back to 0.000Feels like some sort of rounding / fp / devision error creaping inI have attached a HALShow screen - after joggin in cnrements of 5mm the first count was correct at 6400, then after a few it added an extra count then another at 30mm so now shows 30.001 as it must be rounding upHope this helps

Works for me as well with the change Aciera suggested.

We seem to have strayed from the topic...

I tried again today and simply tried other serial channels. When I was at SSerial 5 (7i85 TB1, pin 17-24), my 7i84 was found. So it seems that either there is something wrong with the DB25 - ID24 connection cable (I measured it pin by pin) or with the 7i85 itself. I'm not sure how to check that yet...

 But back to the topic. The bit files work. 
Thank you very much for your help.

Just a quick test and I got large following errors:

 

ini setting are:

 

The 7I76u uses normal 7i92t_7i76 firmware so 7i92t_7i76x1pd.bin

Then select  7i92-internal Data and 7i76x2 with one 7i76:

 

The stepgens are selected from the P2 tab:

 

That's possible, I'll take a look when I get a chance

scsmith1451 wrote:

Is -3 correct for a dual Y axes configuration?

Yes it is, tandem joints must have negative value for homing sequence.