Variable spindle drive schematics?

[byoc]

I think it would be terribly usefully to be able to control RPMs from within the .sbp file. However, I'm little hesitant to reverse engineer my VFD. It's just a matter of finding out if the VFD is using a micro controller or logic counter IC or something else along those lines to recognize the up/down tactile switches that you need to manually push to ajust the RPMs and finding the data sheet for that part.

[richards]

Keith,
If you're using the Delta VFD-B variable frequency drive to control a Colombo spindle, you can select from fifteen pre-set spindle speeds. Basically, the method that you use is to set parameter values 05-00 through 05-15 to the fifteen speeds that you want to use (see page 5-10 in the Delta VFD-B manual), set parameter values 04-04 through 04-09 to control the multi-function input switches (see page 5-07 in the Delta VFD-B manual), and then toggle switches MI-1 through MI-4 to select between the fifteen speeds (see page 2-22 in the Delta VFD-B manual).

What is not explained is the relationship between the switch inputs and the speed selection. I would assume that the switches follow a binary pattern where 0001 = speed selection 0 and 1111 = speed selection fifteen. That would imply that MI-1=bit 0, MI-2=bit 1, MI-3=bit 2 and MI-4=bit 3, such that when MI-4, MI-3, and MI-2 are closed (ground potential) and MI-1 is open that speed 0 would be selected. It would also imply that when all four switches are open that speed fifteen would be selected.

Edited: After thinking about it for a few minutes, I probably gave you upside-down logic. Most TTL circuits are active LOW, meaning that the switch settings would be reversed from what I wrote, i.e., switch open = OFF and switch closed = ON (where OFF = 0 and ON = 1).

I have not tried this, so you're on your own unless someone else wants to share his/her experiences with the group.

[richards]

Keith,
I getting really slow. It took more that the allowed 30 minutes to think this thing through. So, the following should be added to the end of the "Edited" section in the post above:

Using that logic, when MI-4, MI-3, and MI-2 are open and MI-1 is closed, speed 0 would be selected. When all four switches are closed then speed 15 would be selected. Of course, instead of using switches, you could connect outputs from the controller board directly to the switch inputs and then use the SO command to turn the outputs on or off. However, depending on what you're already controlling, you might not have four outputs available for speed control.

[byoc]

Hey Mike,

I don't have the columbo. I have the HSD. But if the up/down buttons only have 0 - 15 that would DEFINITELY suggest a binary counter IC based logic which would be much easier to manipulate than a microcontroller....assuming you've got 2 free outputs in the control box. I don't think 4 outputs will be possible.

Most binary up/down counters have an up and a down input in addition to the ABCD binary inputs....or a "clock" and an "up/down" pin. You could get away by using one out to reset (since your computer will have to work in absolute beginning from zero because there's no way to tell it what position the switch is presently in) and the other out to just send high (or low depending on the manufacturer) pulses to count up and wrap around to zero after fifteen. You could just make the O2 go LO, pause, LO, pause, LO, pause, ect..

[bcammack]

I posted a schematic a while back to interface the unused output switches on the Shopbot control box to the Delta VFD to allow you to control those presets programmatically from your cut file.