I've been working with Panasonic FP0R series controller http://www.clrwtr.com/PDF/Panasonic/Panasonic-FP0R-PLC.pdf to interface with Mach3. My issue is that ModBus seems a bit random in its ability to work. I've tried three different ModBus converters, all with the same basic results - no response, random responses, etc.

I'll have a go at this... but I do not declare myself an expert.

1) that looks like a motion controller

2) rs232 won't work with mach (unless you write a plugin for it)

3) rs485 rtu modbus will work... sort of...  it depends what functions you are trying to access there is a manual here
https://www.google.co.uk/url?sa=t&source=web&rct=j&url=http://www.homanndesigns.com/pdfs/Using_Modbus_with_Mach3.pdf&ved=0ahUKEwi5tOOCqNPPAhUqIcAKHYeaB9QQFghJMAM&usg=AFQjCNFCiN3KferpkfMlGbwoiixsfVL-Yg&sig2=tCsrndJbyuZ1SCm3gt_pRA

4).... motion controller.... hmmm not a good idea via mach3 current modbus application.... the problem is you would need to write your own plugin... because mach3 firstly expects to push motion out to a parallel port.. or motion controller via custom plugin because modbus runs at 10hz and motion is not output via modbus...

Mach3 mach4 will be the same ... you'll need to write a plugin to get faster access to Mach and direct access for motion to be passed put to your motion controller in modbus

(Sorry not living up to my strap line below very well of explaining the problem)

Accidentally on the wrong place

Accidentally on the wrong place

??