Greenie problems configuring 6i25 with 7i77, using Granite Devices VSD-E drives

I took another stab at the GE drive last night. Frankly, the conformal coating makes it really tough to probe, identify, etc. Plus, the drive is pretty old so I'm punting on it. I bought a 5HP unit through Amazon because that way I know it is coming from Huanyang. I opted for the newer GT series which is a vector flux type. Why? Dunno. At 3:3 is about $20 more, but because I went to a 5HP, that was about $60 more. I opted for the more expensive one because I'd rather not have to power up a phase converter if I don't have to and with a 2.5HP spindle motor, I've always been told to oversize the VFD by about 100% if you want to run the VFD on single phase.

Eventually I hope to get rigid tapping working, which is why I went with the 5HP vector unit. My (albeit unsubstantiated) thought it that I'll have better speed control with it... I have to make an encoder mount for the spindle motor, though, which is a bit of a challenge. And, I'm not sure if I'm better off with ModBus (or look alike) control or the 0-10VDC input. My guess is the ModBus is probably better,
but I'm also not sure that I have a serial available (literally just thought about that). I'm delving into an area that I hadn't expected to have to worry about. But, $200 later, I obviously have no choice but to address spindle control.

Alan

As you have a 7i77 I would suggest using analogue voltage control. It works in realtime, whereas Modbus passe through USB and userspace.

I don't know if it is possible to use both at the same time, the Modbus driver gives handy feedback about currents , voltages, etc.

We can probably advise on spindle encoders. If there are any gears rigidly connected to the spindle it is often possible to use those as a code-wheel.

I was wondering about the USB delay, etc. as being a motivation to stick with the 7i77 and analog control. I'm glad you brought that up. . Thank you.

There is only a 1:1 belt drive in there between the motor and the spindle sheeve. However, there is a large disc brake. I plan on installing the encoder under that. I'm not too sure what CPR to use right now though. Any suggestions there? This is a relatively low speed (1980s) machine, so the max RPM is only something like 3500 or 4000.

You could drill a ring of holes in the disc brake and use three optical sensors.

Yeah, I could certainly make an encoder that way. I'm curious about your comment though. I'm assuming that you are going down the path of a phase quadrature and an index pulse (hence 3 photo electrics), right? That is a lot of holes to drill although a CNC could obviously do it (I could run my machine without a brake). But, I also have a fair amount of space under my brake. My original thought was to make a coupling and put a commercial encoder below the plate that way. This is likely easier than making my own encoder from the disc... but I like the idea.

My biggest concern about using a commercial encoder is that I'm not sure I have very many low resolution ones. I mean a 1000 line encoder will result in 4000 counts. At 4000 RPM, that is 266,666 counts per second which is, well, rather quick! . I'm not sure what is 'typical' for spindle encoders. My guess is something closer to 100 lines

No eBay APP ID and/or Cert ID defined in Kunena configurationThe 7i77/5i25 can count encoder pulses at something like 10MHz. You don't need to worry about pulse rate.

If you have the space then yes, a commercial encoder is a good way to go, and some are pretty cheap.

For example (There are cheaper ones, but those tend not to have the index pulse)