Which Viper (Hurco Retrofit)

**Bob La Londe** · 01-01-2011, 12:55 PM

I am in the first stages of retrofitting a Hurco KMB1 to PC based control.

Its got Electrocraft 07 02 03 049 servos, and the power supply seems to be putting out about 90VDC. The power supply is pretty much all I plan to save of the exisitng electronics. I thought about saving the VFD, but its 3 phase in. If I switch it to 1 phase in I don't need a phase converter.

The encoders are falling apart from age so I'll need to replace those. I would like to control with Mach since I am already familair with it (running two stepper machines with it now), but I am not opposed to looking at EMC again.

Anyway. It looks like the Viper 95 should do the job.

I have some questions.

1. Are the Viper 200s necessary or will the 95s be adequate?

2. Will they drive those old ElectroCraft DC servos properly?

3. Do they have an interface to work with the tachometers on the drives?
3.b. Is the tachometer necessary?

4. What reasonabley priced encoders will be easy to setup and work with good resolution with the Viper drivers?

5. What is a good breakout to use between the PC and the Viper drivers?

6. Does the Viper handle correction with feedback from the encoders or does it count on the control software to do that? (That would eliminate Mach. I don't know about EMC.)

7. Can the Viper controllers provide encoder data back to Mach for DRO like operation?

8. What questions should I have asked, but didn't?

9. What are the answers to the questions from questions 8?

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**Larken** · 01-03-2011, 02:10 PM

1. Are the Viper 200s necessary or will the 95s be adequate?
Definitely the Viper 200's since the motors have a lot of Mass. You need a big drive to stop those since they can generate over 100 amps as a generator on decel.

2. Will they drive those old ElectroCraft DC servos properly?
Yes, many have used them

3. Do they have an interface to work with the tachometers on the drives?
3.b. Is the tachometer necessary?
No you don't use the tach signal at all.

4. What reasonabley priced encoders will be easy to setup and work with good resolution with the Viper drivers?
US digital. Use a differential encoder on an industrial machine (don't save $10 and get a single ended) 1000 count E5 or E6 model

5. What is a good breakout to use between the PC and the Viper drivers?
I have a new one or check other vendors.

6. Does the Viper handle correction with feedback from the encoders or does it count on the control software to do that? (That would eliminate Mach. I don't know about EMC.)
The Viper has the PID servo loop built in. Mach only tells it where to go using Step/Direction signals

7. Can the Viper controllers provide encoder data back to Mach for DRO like operation?
I wouldn't recommend using the same encoder for DRO. You will get noise and ground loop problems. Also Mach3 can't read a encoder fast enough to keep proper count. You need dedicated hardware counters to read an encoder. Mach just polls the encoder inputs.

8. What questions should I have asked, but didn't?
Hmm. You will think of a lot more when you go to install.
On the Hurco, the encoders may be ok, but i would run new wires to them (twisted pair). I had a customer where there was a connector hidden in the machine that caused problems.

Larry K

**Bob La Londe** · 01-03-2011, 03:04 PM

Does your breakout have the ability to handle 0-5 or 0-10 VFD control?

Will the Viper 200s handle the inrush on decel without any extra protection?

**Larken** · 01-04-2011, 10:10 PM

Yes the bob has 0-10V output using the PWM mode in Mach3.

The mosfets are rated at 250 volts so decel is not a problem.

I've been trying to finalize my new website which will have pictures and stats on the BOB. But for now here it is.

This is a prototype picture and connectors may vary.