What happened with the G380?

[davo727]

Are they coming up in the near future? Next summer? Never?

Thank You, Dave

[CoAMarcus]

Dave,

The G380 will be coming out some time next year. We have been developing a custom surface mount breadboard so that development will go faster on all drives, and it is nearly finished. This means that development on the G201X, G380, G213V, and stepper-servo will resume.

Marcus

[Mariss Freimanis]

G380 update:

The G380 breadboard was brought-up for the first time today. Please see the attached .gif thumbnail:

The motor is a NEMA-34 servomotor. The yellow trace is the position error while the green trace is the motor current. The motor was caused to turn at 500 RPM while the direction was toggled every 500 milliseconds. The yellow trace shows the motor reversing direction and catching up with where it should be (+/-0.09 degrees) in 40 milliseconds. The scale is 26mV per increment of error. The green trace shows the motor drawing +/-19 Amps on direction reversal. Note the very clean waveforms; what makes them that way is the inclusion of a tunable integral coefficient (3 trimpots now for proportional, integral and derivative coefficients). The G320 integral coefficient is fixed and not adjustable.

The perceptible difference is there is no 'mushiness' when you try to turn a stopped motor by hand. The servo is very 'tight'; it resists instantly and there is no observable slight rotation and position restoration as with the G320. The servo lock range is a ridiculous +/-32,000 counts compared to the G320's +/-128. This may be pared-down to something more reasonable.

What worked today is the engine core; engine block, crankshaft, cylinders, pistons and valves. In the next several days all the promised G380 features will get added and be tested. They are the oil and water pumps, air-conditioning, and alternator in this analogy. Once they are running correctly, the G380 prototype board layout will begin.

What may fall out as a secondary product might be the G350 and G351; small-size, low power variants. Their size will be the same as the G250/G251 microstep drives. The price will be similar as well. The ratings may be 10A @ 50VDC; I don't know yet but that seems about right.

Mariss

[davo727]

Thanks for the update. Sounds great, when they are ready I will be buying them for my mill project. Dave

[Mariss Freimanis]

G380 update, the carry-on and eventual replacement for the G320:

A semi-major breakthrough today. How about a servodrive that is almost silent without any anti-dithering workarounds? The only sound you hear at any speed is the faint hiss of motor ball-bearings in their races and nothing else at all. Motor grunts and groans are totally absent.

I demonstrated my breadboard to our technicians today. The one that tests G320s thought it was a trick. He had to get eye-level with the motor to see it was turning at 1 RPM. Next he had to grab the motor shaft and see he could elicit a groan from the motor torquing it by hand. No dice; the motor was totally silent. Couldn't move it more than +/-0.18 degrees either; the scope was on it recording his efforts. Ran it 0 to 3,000 RPM and still silent. It was 6PM, all the production machines were off and the shop was silent. The only sound anyone heard was motor ball-bearings.

This will make Leadshine cry. We are no longer working for them as an unpaid R&D lab so no more DB810 (G320) next generation drives for them. They won't be able to pirate this drive.:-)

Mariss

[rowbare]

Originally Posted by Mariss Freimanis What may fall out as a secondary product might be the G350 and G351; small-size, low power variants. Their size will be the same as the G250/G251 microstep drives. The price will be similar as well. The ratings may be 10A @ 50VDC; I don't know yet but that seems about right. Mariss

That would be tres cool... Do you think you be able to re-use the G540 Motherboard for it?

[cut more]

Thanks you for continuing to develop great drives at great prices!

I hate to ask this question but, Do you have a ballpark idea when these will be available?

I am not going to hold you to an answer, just looking for a ballpark.

Thank you,
Cutmore

[Mariss Freimanis]

It will be soon. I have changed my design tactics from making prototype boards to using specially designed breadboards.

To stand any chance of success, a prototype board must be 95+% correct; they are not tolerant of major changes. On the other hand, a breadboard is meant for large changes because all the interconnects are hand-wired. I took some time out to design what for me are ideal breadboards; dual full bridges, two CPLDs, 16 op-amps and comparators, 200 0603 resistor/capacitor locations, 24 SOT-23s, opto-isolators, headers, trimpots, connectors, regulators, tactile switches, etc, etc. It's flexibility is beyond my expectations.

A dozen ways the G380 is different from a G320:

1) The servo lock range is +/-2,048 counts and it uses a 12-bit D to A converter (8-bit and +/-128 on the G320).

2) The power section is a current-mode amplifier (G320 is voltage mode).

3) All the PID coefficients are settable (P and D only on the G320).

4) The current limit is timed (defeatable), at 1 second for 20A, then drops back to the LIMIT trimpot setting (no more burned-up motors if run into a hard stop).

5) The bridge switching and current sensing has been redesigned to tolerate hard-stop motor crashes (no more popped drives when the motor is run into a hard-stop).

6) It has a built-in 1, 2, 5 and 10 encoder divider so it's like a G340 (the divider cannot be fooled like the G340).

7) The G380 is also totally silent (no servo "grunting" or audible step noise). It doesn't use "anti-dither" or dead-band tricks so there is much greater servo stiffness.

8) The STP/DIR optos are universal interface; you can put GND or +5V on COMMON without any header jumper settings.

9) There are 4 LED indicators, POWER, FAULT, WARN and INPOS. WARN lights when the motor is in current limit or when the following error is greater than +/-256 counts. INPOS (in position) lights when the following error is less than +/-2 counts and should help with selecting acceleration and velocity settings in the CNC program.

10) Short-circuit, temperature, reverse polarity and overvoltage protection.

11) ERR/RES separated into a FAULT output and RESET input or settable to ERR/RES as in the G320.

12) Optoisolated CH_A and CH_B encoder inputs. Use any encoders you want and power them from a single PC ground-referenced +5VDC supply.

For those that want a servo amplifier only, I'm looking at having a +/-10V input and a tach input.

The first version will be an exact fit and function replacement for the G320. It will not have items 11, 12 and the integral coefficient trimpot will not be accessible without removing the cover. That trimpot will have a factory default setting equal to the G320 hardwired setting. We're looking to do all of this at the G320 price.

Mariss

[acondit]

Originally Posted by Mariss Freimanis It will be soon. I have changed my design tactics from making prototype boards to using specially designed breadboards. For those that want a servo amplifier only, I'm looking at having a +/-10V input and a tach input.

Mariss,

How about PWM inputs?

Alan

[Mariss Freimanis]

The common PWM interface is 'PWM' and 'DIR'. Because the G380 uses a CPLD, these signals could pass through the STP and DIR optos on a custom programmed G380.

Mariss

[Xerxes]

About current-mode amplifier, does it have adjustable gains as well? Those are usually necessary since amplifier behavior depends on motor resistance and inductance. With fixed gains some motors may have sluggis performance and in some cases the amplifier may become unstable.

[edferg]

Having built stepper systems around Gecko drives, including the G540, I'm pretty comfortable working with them. However I am new to the world of servo motors.

I have a 20 year old Omni-Turn CNC retrofit on a Hardinge lathe. At some point something is going to die, and I want to have a modern computer/controller in place before that happens. I could probably retrofit new DC motors, Gecko drives, computer & software for 1/2 the price of having the old controller repaired. Plus I would gain capability with new software, and have a system I can repair myself.

For this reason I'd like to see at some point a list of recommended motors for the G380. I guess specing the motor is not too hard, but I'm clueless about encoders.

Have a list of known good motor/encoder matches for the G380 would be a starting point for taking some of the guess work out.

Ed