On-Motherboard Modbus / RS485 connection

I have swapped my Lovato 3hp VFD for a Huangyang 4hp VFD as the Lovato had no RS485 protocol definition, and over-currented when running my lathe spindle motor. The HY VFDs have an already-written HAL component for control.

Using a USB RS485 dongle it turned out to be far too easy to get the spindle turning, so I decided that I would make things more difficult.

The USB dongle looked like this and cost a couple of £ from eBay.







It stuck a long way out of the computer, and didn't really suit my installation, where the motherboard is simply fastened to the back of the control cabinet of the lathe. I decided to try to connect it to one of the motherboard headers.

Fortunately the USB connector pin ordering is the same as the motherboard header (probably not a major surprise) so I was able to solder a bit of header strip (with the pins bent through 90 degrees) onto the dongle in place of the USB plug.







And then I could mount the whole thing on the motherboard, saving a USB connector and also avoiding several DB9s (which all the other options seem to require).





I intend to replace the screw terminals too, so that I can have a gnd/shield on the cable.

cncnoob1979 wrote:

Which one did you buy?

www.ebay.co.uk/itm/121106393167

(though it is, of course, no longer a valid listing)

It is more important to know what you are connecting to. I am using a Huang Yang VFD so the hy_vfd HAL component does all the work.

Does this HAL component look like it would help?
linuxcnc.org/docs/stable/html/man/man1/vfdb_vfd.1.html