OAK compatibility with Siemens 611a (analog) AC servo drives

[Jaze86]

Hey everyone, first time poster....long time listener.

I bought a Hyundai Hit8s with a Siemens 840c control and it is an electrical nightmare. I searched and could not find any successful conversions, I was hoping someone in here had some experience with the 611 analog Simodrives. I am currently on a wild goose chase for the manuals which seem to be extinct.

I know the spindle can be controlled via 0-10v but the X and Y have "tachometers" in them which seem to be proprietary to Siemens. I don't mind using new drives and servos but I would really like to re use what I can. The drives themselves are fine but the PLC CPU seems to be falling apart and not allowing for long NC operation.

Any reading material for a guy who bought a fantastic lathe but horrible controller?

[cncsnw]

Assuming those are the "Simodrive 611" system that was found on some Bridgeport VMC machines; and assuming that all such drives have the same interface features; then they should be controllable with the Oak.

The only significant issue is that the Siemens drives require a +24V signal (positive logic) to enable, while the Oak will only provide a pull-down-to-0V (negative logic) enable signal. This requires that you insert a relay between the Oak and the drive, so that Oak can activate the relay (enable signal to minus side of coil); and the relay can switch +24V to the drive's enable input.

You also need a quadrature differential encoder signal to the Oak, for axis position feedback. In my very limited experience with Siemens drive systems, it is typical to have a separate encoder for that purpose (separate from the tachometer or encoder that provides feedback to the drive). Bridgeport VMCs, for example, have two encoders on each motor: one wired to the drive and another wired to the CNC control.

For an example of a retrofit with Simodrive 611, see:
https://centroidcncforum.com/viewtopic. ... 97&p=53792

[Jaze86]

Assuming those are the "Simodrive 611" system that was found on some Bridgeport VMC machines; and assuming that all such drives have the same interface features; then they should be controllable with the Oak.

The only significant issue is that the Siemens drives require a +24V signal (positive logic) to enable, while the Oak will only provide a pull-down-to-0V (negative logic) enable signal. This requires that you insert a relay between the Oak and the drive, so that Oak can activate the relay (enable signal to minus side of coil); and the relay can switch +24V to the drive's enable input.

You also need a quadrature differential encoder signal to the Oak, for axis position feedback. In my very limited experience with Siemens drive systems, it is typical to have a separate encoder for that purpose (separate from the tachometer or encoder that provides feedback to the drive). Bridgeport VMCs, for example, have two encoders on each motor: one wired to the drive and another wired to the CNC control.

For an example of a retrofit with Simodrive 611, see:
https://centroidcncforum.com/viewtopic. ... 97&p=53792

Excellent, that link seems to have very similar drives to mine which is excellent news. Those issues you listed also seem to be easily solved, I think i am ready to take the plunge if and more likely when the machine kills another PLC CPU.

You are correct that all of the axis have a separate encoder aside from the internal positioning encoders. I have a plan B/worst case plan to use the spindle Simodrive since it would be 0-10v control and replace the X and Z with more suitable servos and drives for the Oak. <y goal is a quick install as I am production shop and in need of this lathe to work badly.