Hello

I have a strange problem:
when the Huanyang VFD is connected to mach 3, the "goto Variable position" is acting strange: X and Y go normaly to the memorised position, but Z goes to the zero machine coordinates...
If I disconnect the VFD (connected via RS485), everything is fine.

any idea what could be the problem ?

Hi,
sounds like the VFD/spindle are producing enough electrical noise to interfere with the home switch circuit of the Z axis.

There are two schools of thought as to how to stop this.

Most people start by using screened cable for the home switches and fitting capacitors or other filters to the signal line.
These are all examples of 'reducing the sensitivity of the signal circuit to EMI'. This often works but is, in my opinion,
not the right place to start.

The other way is to reduce the EMI produced by the VFD/spindle. VFDs are notorious for drawing power from the AC
supply in a very ragged or noisy way. A line reactor is the correct way to tame a VFD. Most people don't do it because
of the expense. With a large VFD in industrial situations the power company may well insist that you do so. A large
line reactor or power factor corrector device can be a substantial fraction of the price of the VFD.

A line reactor is a coil of wire on a laminated iron core (inductance approx. 5mH) and is fitted between the AC input
and the 230V input of the VFD.
Note there are special filters that you can put between the VFD and the motor, usually only required if there is a big
distance between them. You should follow the manufacturers specs very carefully if you decide to add these types of
filters. Standard line filters are likely to damage the VFD.

A couple of things that you can try before you decide whether you have to buy anything.

1) Try some de-bounce and/or fit a 0.1uF capacitor to the Z axis home switch line.
2) Connect your VFD to a different AC socket preferably well removed from the AC socket you connect your PC and
controller power supply.

Craig

thanks for your response

Does the VFD produce noise even when the spindle is not running ?

Hi,

Does the VFD produce noise even when the spindle is not running ?

No, I should think not anyway. The VFD starts to draw significant current only when the motor runs, and then it draws
current from the supply in short high current bursts rather than smoothly and that causes EMI. A line reactor 'smooths'
out the current and incidentally much improves the power factor.

When the motor is not running and the VFD is sitting idle there will still be a small amount of current draw as the auxillary
flyback inverter draws a few mA's to supply the VFD with a DC power supply. I would not expect EMI from that source
to cause your problem. If it does you are going to have a real battle when the motor runs and REAL current gets drawn!

On large industrial VFDs the AC supply to be used to convert to DC for the VFDs control circuits is separate to the main
AC input. That would allow much tighter filtering of the AC to DC supply without having to use hugely outsized and
expensive components should they have to withstand full input current.

Craig

when the spindle is running, I can hear little harmonics in the steppers but it works fine. The only odd thing is the "goto variable position".
I did try with the vfd turned on but disconected from mach3, it works fine.
I have the problem only when the communication is estabished via the rs232/rs485.
I tried to make a new setup from scratch, supposing the xml file had been corrupted, but nothing changed.

I can live with that problem, even though I love that function and use it a lot, but I would like to understand what's wrong (and eventually get this function back

I add that I wired everything with shielded cables, taking good care of separating steppers cables and spindle cable paths, as well as power and signal cables.

Fred

Are you using Matty Zee's plugin for the Huanyang VFD?
If so, some people success using a "USB to RS485 converter" to get that plugin working.
Follow the plugin thread
https://www.machsupport.com/forum/index.php?topic=14182.0

Hi Reult,

yes I did, and even tried another one from Royaume d'eole. Both work fine.
The USB/RS485 I'm using is that one:
https://www.amazon.fr/gp/product/B07B416CPK/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
After many investigations, it seems that as soon as the plugin is active.

UPDATE:
As I wanted to give you as many informations as possible including a copy of the scripts involved, I found the problem !
It was a USERDRO conflict.
the script of the "set variable position" is using the same default USERDRO of the VFD monitor:
x = GetABSPosition(0)
y = GetABSPosition(1)
z = GetABSPosition(2)
SetUserDRO 1000, x
SetUserDRO 1001, y
SetUserDRO 1002, z

Happy ending

Fred