Bosch VFD and rs485

Hi. I would first like to thanks Andy for the help in getting my lathe sub routines done. It works great. My lathe is 99% complete, just left spindle control. That's where I am stumped. This is all very new to me. I have a Bosch EFC3610 VFD thats supports modbus and rs485 input. I have bought a usb to rs485 adaptor but have no idea how to set up my lathe so Linuxcnc controls spindle speed. Its a 0.75hp 3 phase motor. The VFD controls the speed using the VFD panel well, installed and tested it today. The software side has got me stumped. Also, the spindle speed display in axis works (my lathe has a index and phase a). But it only shows speeds up to 115RPM, then got back to 0, even though motor spinning at about 1000rpm. Is it my optocouplers, the way I have set it up, or just me....lol. If anyone can help. I have searched on here but just got even more confused reading peoples very clever electrical terms, way over my head. I am an engineer, machine shop etc - electronics are very very new to me.

How many counts per rev is your encoder?

Setting up the VFD might be something of a project if there isn't already an existing HAL module for it.
linuxcnc.org/docs/2.7/html/drivers/mb2hal.html in conjunction with the VFD manual probably has all the information you need.

You might find it easier to use analogue voltage control.

Hi. My encoder plate has 45 holes due to small space available. I have however noticed my BOB does NOT have a pin for 10V control so have ordered another board. Decided to go with analogue control as modbus seems to be unreliable with a usb dongle.

My lathe spindle is perfectly reliable with a USB dongle, but that is using a VFD which already has a dedicated LinuxCNC driver.

45 holes @ 155rpm is only 116 Hz, so even a software encoder counting in the servo thread would be able to cope. So I am rather puzzled what could be going on there.

Can we see the HAL file?

Hi. OK, I can send you a screen shot. Its very strange, it goes up to anout 190rpm then falls back to 0 as I increase the speed. I was wondering if maybe the infra red optocouplers from ebay are CR@P

It could well be the optos. Do you have a real oscilloscope to look at their output with?

Alternatively, if your multimeter has a frequency measuring capablity, that might tell you if the problem is in the hardware or the software.