Speedcommand Modbus driver for An Altivar ATV71 VFD

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16 Mar 2017 11:41 #89737 by christian99x
christian99x created the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
We are using the following module for controlling our VFD:

wiki.linuxcnc.org/cgi-bin/wiki.pl?Contri...ATV71_VFD_driver_atv

The link to the git is down, but it's available on another forum:

www.c-n-c.cz/viewtopic.php?f=34&t=4869

The problem is, that the start/stop command works, but the speed command doesn't (We had this working, so I know it's possible). I found out, that there are two different addresses for these two commands, but I don't know where to set it. I searched the settings of the VFD, but I could not find this parameter.

Any help appreciated - Thanks !
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16 Mar 2017 19:22 #89774 by andypugh
andypugh replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
Have you looked at the component code?
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17 Mar 2017 14:42 - 17 Mar 2017 14:46 #89825 by christian99x
christian99x replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
Yes - in the xls file with the atv parameters I can find:

CMD 16#2199 = 8601 (speed)
16#2135 = 8501 (frequency)

....and in the code I can find:

#define REG_CMD 0x2135 // Control Word CMD 8501 frequency


So I would say it's correct ....... but it's not working....


Do I have to set the address in the atv or is it fixed??
Last Edit: 17 Mar 2017 14:46 by christian99x. Reason: correction
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12 Nov 2017 10:44 #101680 by christian99x
christian99x replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
I analyzed the problem further and I found out, that the atv_vfd module IS sending out a speed command. Unfortunately it's not the right one. If I send out 6000rpm (which is 100Hz at the ATV and the lowest speed of our spindle) the ATV runs at 12,5Hz, with 9000rpm 18,7Hz etc.

I really have run out of ideas where the problem is. Maybe someone can point me in the right direction!

Thanks a lot in advance!
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12 Nov 2017 10:56 #101683 by andypugh
andypugh replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
Easy answer: Just send 8x the speed you really want :-)

It is hard to see what might be doing this at the VFD end. An easy explanation for the inverse problem would be that the motor poles setting is wrong, but it seems unlikely that it could be configured to be a 0.25 pole motor...

So, just fudge things in the code that you do have access to.
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12 Nov 2017 13:01 #101696 by christian99x
christian99x replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD

Easy answer: Just send 8x the speed you really want :-)


Well - I had this idea already ;-) .... We had it working, that's why I actually don't want to fudge it.... but maybe that's the "easiest" solution....
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12 Nov 2017 13:14 #101697 by andypugh
andypugh replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
Ah, so it used to work and now doesn't?

Did anyone change any settings at the VFD?
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12 Nov 2017 13:27 - 12 Nov 2017 13:33 #101698 by christian99x
christian99x replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD

Ah, so it used to work and now doesn't?


We had a working setup, but the PC had a disk failure and so I had to set up a new one, compiling the module etc. I managed to get everything running again except the speed of the spindle.

I'm fiddling around with this issue for a while and we had backups of the config files and the setup in the VFD, but I have no idea from when these backups are. Unfortunately I can't ask the guy who set up everything (incl. working speed command) up :-( ....

The problem is my limited understanding of the technical background (but I'm willing to learn ;-) ) and that I don't really know where the problem lies: in the settings of the VFD, in the config of LinuxCNC or the source of atv_vfd module.
Last Edit: 12 Nov 2017 13:33 by christian99x.
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14 Nov 2017 13:53 #101775 by andypugh
andypugh replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
A factor of 8 sounds like perhaps the data is somehow shifted in the code.
I guess this comes down to what the VFD manual says that the register is meant to contain, and how the HAL module is composing the data.

Maybe the original working config was multiplying by 8?

Can you attach the actual .comp file to a message so that we can see it?
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15 Nov 2017 08:56 #101826 by christian99x
christian99x replied the topic: Speedcommand Modbus driver for An Altivar ATV71 VFD
Yes - the developer was so kind and point me to the line in the code, where the frequency is calculated, I changed the relevant factor and now everything is working like expected ;-) !

Thanks a lot!
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