[pminmo]

Ito,
Did you configure your axis for turbo cnc?

Phil

[Ito-Brazil]

Phil:
My axis configuration (all the same , just for test)
Motion: LINEAR
Drive Type: STEP/DIR
PulseWidth: 45
Port: 0X378
STEP PIN NUM: 8
STEP Pin is: Active HI
DIR PIN NUM: 9
Direction pin: + is HI
Motion Parameters:
Scale: 0.00079375
ACCEL: 60 Hz/s
Start Vel: 60 Hz
Maxvel: 100 Hz
BackSlash: 0 mm
Slow jog: 50 Hz
Fast Jog: 100 Hz
Jog keys: Normal
THANKS FOR HELP!

[pminmo]

I assume you do have Pin 8 of the db25 port connected to the driver step and pin 9 to the driver direction?

Phil

[Ito-Brazil]

Right, Phil. With the LED board its lights, PIN 8 low light when TCNC calls, pin 9 hard light.. I´m mounting my POWER resistors to test with the motors right now. Maybe it works...
Other thing: if i change the configuration to PIN 9=STEP / PIN 8 = DIR, it hapens too, but the pin 9 that ights low.

[Ito-Brazil]

Well, something courious is hapening. I put the motor to work. At the FKEYBIT (test program) it worked bery nice, but at the TCNC , that it was working as LEDS (DRIVER board driving leds), it simply do a single step...

[pminmo]

Ito,
I'm not understanding.
?

Phil

[Ferenczyg]

I think that the low glow in the step pin led is ok, because you are feeding the led with a kilohertz pulsing signal. Think of it as you are using a sort of pwm to the led, then the average voltage you feed to the led is about half the voltage to make it glowing at full. If you put a multimeter to the pin in the DC range you will see about half the logical voltage of the lpt port.

By the same reason, the full glow ath the dir pin led is because the dir signal is more 'continuous' at high level or low level, more like 'Vdc ON/Vdc OFF'


/Fer

[Ito-Brazil]

Well guys, i finally got the good steps. I´m still having problems with the DIR comand and i don´t know why i must chanche the PIN number sometimes. I think it´s because me: absolutely unexperience with CNC configurations, hehehe.
I will post something new when i restart to mount it. I had MEchanical problems, the machine is faster than i imagine, so the coupling can´t hold the motor without a fixing screw. Learning to perfection!
What´s the standard speeds to the DISCRETE board ?
Thanks guys, i listened the "robot" sound this week! amazing!

[Ito-Brazil]

Phil:

I tryed 2 times to do a OPTO-Board to protect my LPT port. It´s ok when i put leds and it really step very nice, but on DIR capabilities i think the voltage is low: about 3.7 V.

May I use lower resistors on R7 or R4 ? I don´t know what resistor should i change...

I think that´s the cause. I tested short circuit the DIR-Ground and it worked good, maybe changing the resistors it work fine with my 4N25 OPTOS.

Thanks a lot!

[pminmo]

3.7V shouldn't be a problem. What value of resistor do you have from the PC parallel port to the 4N25? I assume your referring the 3.7vdc measurement on the input at pin3 of the stepper driver board to it's ground? And that would be with the PC port pin set low? What do you measure when the PC port pin is High?

Phil

[Ito-Brazil]

Phil:
I tested right now again:
-I use a 1k RESISTOR from LPT1 to 4N25 = 3.69V. It works fine with LEDS ans STEP features...
-When the PIN from LPT1 is OFF, there is 5.02V
-When the PIN is ON, there is 4.56V
Look: if i change R4 and R7 on Discrete UNIPOLAR board from 1k (both) to 10k, should it work ?

[Ito-Brazil]

Phil:
I did 2 versions of the opto-board

Last one (ver 2.0) has all the OUT-GND isolated. It´s nice to control diferent things. In both boards i can´t DIR, only STEP my motors.

* Remembering that i use 1K resistor from LPT1 to 4N25.

Thanks A LOT !

[pminmo]

Switching the 1K's to 3.3K ought to do the trick. You could also lower your series resistance, but that would depend on your PC's ability to source (provide) more current. The thing about optoisolators is they switch faster at higher currents, so in theory raising the 1K to 3.3K would slow you down some, verses 1K with 370 ohms in the base.

Phil

[pminmo]

A pretty simple overview of opto isolators is here:

http://homepages.which.net/~paul.hil...rol/Optos.html

[Ito-Brazil]

OK PHIL :
- change the 1K resist between LPT and 4N25 from 1k to 370
- Change both 1k resists on Discrete (R4 and R7) from 1k to 3.3k

Is that correct? Shops are closed now, but tomorrow it will be my first objective,hehehhe!

I´m studying the site you send, thanks Phil! You are the one !

[pminmo]

You should be fine just changing R4 and R7, unless your going to run a real high step rate.

Phil

[tekno]

I would like to build an opto baord. I was wondering if the 4N25 would be fast enough.

tek

Phil:
I did 2 versions of the opto-board

Last one (ver 2.0) has all the OUT-GND isolated. It´s nice to control diferent things. In both boards i can´t DIR, only STEP my motors.

* Remembering that i use 1K resistor from LPT1 to 4N25.



Thanks A LOT !

[pminmo]

4N25's aren't great, but there not bad, probably for a lot of hobby machines thye will suffice. Another choice would be the TLP624 series. The one thing about the 4N25's that bothers me is on manufacturer spec had a pretty big varience in propagation delay, 100us as I recall.

Phil

[slowboy]

Hi Everyone,

I'm failry new to all this cnc stuff too.

I quite like the idea of having an isolated parallel port as my pc came close to a near death experience.

After much hunting around i came across several devices commonly used for isolating these ports.

Hope this list helps.

IL74
ILD74 These 3 are vishay devices in single, dual or quad configuration.
ILQ74 They have a typical switching time of 3us.

PS-2501-1 NEC devices single. Typical switching time 3-5us

Cheers, Rob

[H500]

One thing to note is that they need to be driven pretty hard to get the stated speeds (ie: 50ma). I don't think a parallel port can put out that much current.

I'm thinking of using transistors and zeners instead. Not as safe as opto's but perhaps good enough for 30-50v supplies.