parallel port versus pci card system

[js412000]

I am new to EMC and am trying to get all the terminology straight.

From my reading it seems like there are two ways to go when implementing a system. please correct me if I am wrong.

The first method is to use the parallel port on the back of the computer, where the printer would plug in.

The second method is to use a pci type card. One would have to take off the cover of the computer and plug the card in where a modem or graphics card would go.


I am planning a "big iron" project, and am not sure how to proceed.

I have fanuc 20 amp 146 volt ac brushless motors.
I do not have servo amplifiers yet and could probably get by with less than the full rated torque.
It won't have a tool changer to start, but will eventually.

Which way is better? Can both be used simultaneously ?

[acondit]

What a standard parallel port really won't handle is high count encoders being read in software. The computers just aren't fast enough.

I would suggest a Mesa 5I20 pci card. It has plenty of IO and will handle the encoder reading in hardware. The parallel port on the back of the computer is fine for smaller systems and can even be used for larger systems with something like the Mesa 7I43. The 7I43 is a lot like an external 5I20 (accessed via a parallel port instead of the pci bus).

Alan

[js412000]

Thanks for the response.

I see where the 5i20 plugs in to the computer.
It has what look like three 50 pin ribbon cable connectors.

Does the pwm signal come out of the 5i20 and go directly into the servo amplifier, or is there something in between?

I realize that If I choose a servo amplifier that only accepts analog +- 10 volt command signal I will then need some kind of adapter/converter.

What is FGPA?

The encoders have 2000 pulses.

[acondit]

Originally Posted by js412000 Thanks for the response. I see where the 5i20 plugs in to the computer. It has what look like three 50 pin ribbon cable connectors. Does the pwm signal come out of the 5i20 and go directly into the servo amplifier, or is there something in between?

I believe that the 5i20 produces the PWM signal directly. You will probably need some sort of breakout connector to fasten connections to the ribbon cable (encoders, limits, servo drives, etc).

I realize that If I choose a servo amplifier that only accepts analog +- 10 volt command signal I will then need some kind of adapter/converter. What is FGPA?

I believe that FPGA stands for "Fully Programable Gate Array". Think of it as the "I can be what ever you want" chip.

The encoders have 2000 pulses.

I believe Mesa also sells some digital (PWM) to analog (+-10) converters. I think that Jon Elson (Pico Systems) also sells d/a converters, servo drives, etc.

Alan

[123CNC]

If you use Mesa 7i33 daughter boards, it will convert 4 channels of 5i20 pwm to +10V analog servo control signal.

There are also USB and parallel port variant, Mesa options continue to grow. You may want to carefully peruse all their hardware and capabilities.

Peter will help you out should you run in to some technical difficulties. I would say I'm a fan.

[jmelson]

Originally Posted by js412000 I am new to EMC and am trying to get all the terminology straight. From my reading it seems like there are two ways to go when implementing a system. please correct me if I am wrong. The first method is to use the parallel port on the back of the computer, where the printer would plug in. The second method is to use a pci type card. One would have to take off the cover of the computer and plug the card in where a modem or graphics card would go. I am planning a "big iron" project, and am not sure how to proceed. I have fanuc 20 amp 146 volt ac brushless motors. I do not have servo amplifiers yet and could probably get by with less than the full rated torque. It won't have a tool changer to start, but will eventually. Which way is better? Can both be used simultaneously ?

There is another solution. I have boards that use the parallel port as a communication link. I have a couple flavors of systems. They all have encoder counters and some form of output to match the servo amp. One system has PWM output for servo amps that take a digital signal, the other has analog output for analog velocity servo amps. I also have a brushless drives that go to 20 A. I have tested them up to 120 V DC supply, but they should be able to handle 140 V if you actually need that much RPM. Most likely, you don't need the full motor RPM, though.

The advantage of this is that you don't need to put anything inside the computer, and it may simplify the wiring.

Oh, Fanuc motors? Red cap? You should know that the standard Fanuc "red cap" motor with the "pulse coder" encoder are proprietary, and normally can't be used with industry compatible servo drives. I now have a converter board that allows you to use these red cap motors with industry compatible drives, as well as my own brushless drives.

You can see these items at http://jelinux.pico-systems.com/oscr...alog/index.php

Jon

[js412000]

Thanks for all the responses. I have a lot of studying to do.