[CNCMAN172]

Found the Manual, these drivers actually have opto-isolators inside the driver which should respond to the parallel port outputs without an issue. The PU pin#8 is the STEP pin, and the CW/CCW pin#7 is the direction pin. You also must use Pin#3 the logic ground pin. Did you say the motors will only move in one direction? If so that says the driver is taking the step single without issues.

Russ

[Shelby5041]

Yes 1 direction and note this is a manufactured engraver not a diy build...so any wiring schematic design should not be an issue ...it was controlled dos and parallel port originally



TE=CNCMAN172;2505874]Found the Manual, these drivers actually have opto-isolators inside the driver which should respond to the parallel port outputs without an issue. The PU pin#8 is the STEP pin, and the CW/CCW pin#7 is the direction pin. You also must use Pin#3 the logic ground pin. Did you say the motors will only move in one direction? If so that says the driver is taking the step single without issues.

Russ[/QUOTE]

[CNCMAN172]

Are you sure you have the parallel port worked correctly to the drivers? Look at this diagram and start with just one motor like the X motor.

Attachment 478960

Pin#2 is X DIRECTION
Pin#3 is X STEP
Pin#25 is Ground

If you reversed Direction and Step you will have a problem like yours.

Russ

[CNCMAN172]

If this worked with DOS and the Parallel port, it will work with Windows, Mach3, and the parallel port. Did you buzz out the parallel cable you are using, so of these cables look like parallel cables but were actually 25 pin serial cables. Actual printer cable had a different connector on the printer end.

Russ

[CNCMAN172]

What voltage do you measure from Opto IN and Logic Common? This is the voltage the opto isolators inside the drive are running on.

Russ

[Shelby5041]

i dont know

hi

ok i did a test today

i removed the dir wire from the driver to simulate open circuit and per manual this will casue a logic high

the motor motor moved in the opposite direction

so this means the driver and stepper motors are good as i figured and its a voltage issue

apparently 3.5v is not high enough to trigger logic high

so i will need to find a pc parallel port that outputs 5v instead of 3.5v

[Shelby5041]

hi cnc man as i have said the parallel cable and pc works with all my other mach3 machines with zero issues......after the test i just performed i believe .the issue is the old stepper drivers are looking for 5v and my parallel port puts out only 3.5v...and 3.5v is not high enought to trigger logic high to change stepper direction.

[Shelby5041]

in mach3
pin2 x step
pin3 x dir

pin4 y step
pin5 y dir

this is not a mach3 issue

[CNCMAN172]

Shelby,
Let's think about the interface logically. You have verified the drivers indeed do work and can move the motors in both directions. Your thought is the voltage level is not high enough, meaning it is not at a full five volts. Keep in mind all the output pins from the parallel port are being driven exactly the same way. If the driver interface required a full five volts to work, then you would have no movement at all. Why? The step pin is being pulsed and it is causing the motors to spin and they are being pulsed at 3.5V. You have proven if you disconnect the direction pin the driver allows the motor to move in the opposite direction. This suggests the interface is pulling down a open collector signal when it should be doing nothing to decrease that signal level. My guess is your parallel card does not have pull up resistors on the output pins. Instead they are just floating.

Are you running the parallel interface wires directly to the drivers or are you using a breakout board. The link below is one example of a breakout board.

https://www.ebay.com/itm/15283391943...3ABFBMoIWL3olg

If you are not running a breakout board then you could have a parallel port that does not use pull up resistors. If you have a couple of 1000 ohm resistors you could run an experiment. You connect one end of the resistor to the direction signal and tie the other end of the resistor to 5V supply. This will pull up the output signals, which will require the Mach3 software to issue low signals to change the output.

Russ

[Shelby5041]

this 1980s engraver does not use a BOB...the wires from driver boards go directly to a 25pin parallel male adapter at back of machine where parallel cable connects to..i have resistors but not sure i have any 1000ohm..what range of values of resistor could i use? and what you mean 5v supply? there is no 5v supply..the signal voltage to direction pin comes directly from the parallel cable...so would i tie 1 end of the resistor to the direction pin and other end to the parallel dir signal wire?

fyi and using logic when it comes to different era electronics doesnt always work lol...i know becasue i have worked on many old cnc machines that just dont function with modern technology hardware etc...once i looked at the manual for the driver and saw the refernece to 5v i then started thinking i bet that may be the issue..i also then searched online and found out that some parallel cards output 3.3v and some do 5v...so that steered me into thinking it could be a voltage issue rather than failed drivers and failed steppers....the odds of 2 drivers and or motors failing with exact same symptom is basically zero...

thansk for your help i will see if i can find a pc with a 5v parallel output or retrofit with a cheap $10 BOB off ebay....however doesnt the mach3 bob board need 5v input power as well as 12v input power?...i dont want to make this a project and i rather keep the machine orig vintage...ill porb just stick to looking for an old pc..can get for free most of the time.

[CNCMAN172]

That's what I figured. You have two choices you can buy a cheap breakout board that uses pull up resistors and possibly opto-isolators, or you can search for an old parallel card that has pull up resistors. If you run my resistor experiment you will discover it will work correctly.

Russ

[dazp1976]

this 1980s engraver does not use a BOB...the wires from driver boards go directly to a 25pin parallel male adapter at back of machine where parallel cable connects to..i have resistors but not sure i have any 1000ohm..what range of values of resistor could i use? and what you mean 5v supply? there is no 5v supply..the signal voltage to direction pin comes directly from the parallel cable...so would i tie 1 end of the resistor to the direction pin and other end to the parallel dir signal wire?

Basically this in the image:

https://www.mccdaq.com/TechTips/tt-images/pullup.jpg

You join a 'spur' wire with a resistor to the output wire going from the pport to the driver. (It can de added at the driver screw terminal).
Then send that spur line to the positive on a 5v supply. It then pulls up the parallel output to the 5v level.


It's not entirely clear but I'd assume you'd also sent the 5v supply negative line to the pport ground too so the supply 'registers' with the port.


I've been playing around with some bits and bobs directly connected to a LPT parallel interface on both I & O and the above is how its worked so far.

[Shelby5041]

thanks

today for the hell of it i ran 5v directly to the dir pin using an old 5c cell phone charger

as i suspected the motor turns in cw direction which means it is seeing logic high

so im pretty confident a 5v signal is needed ... 3.4v is not enough from parallel port

[Shelby5041]

Ok i just tried another desktop pc ..its an old hp from 2002...the parallel port is only feeding 3.5v to the dir pin.

I guess i may need to research parallel ports that output 5v... pc or use alternative method as mentioned.

[dazp1976]

Ok i just tried another desktop pc ..its an old hp from 2002...the parallel port is only feeding 3.5v to the dir pin.

I guess i may need to research parallel ports that output 5v... pc or use alternative method as mentioned.

Sounds like it wasn't originally pc controlled and had its own specific off-line system running off 5v power.
The DDCS4 type of thing for example.

I guess this is why db25 breakout boards with an external 5v supply are needed to use a pport pc for cnc control.

Just get yourself one of those 5 axis boards for less than £10 and a suitable db25 cable to make use of the old pc.

[Shelby5041]

thats what i may have to do...i beleive there is 5v feeding the opto so i can maybe use that 5v to power the bob logic..i do beleive though that the bob needs another higher voltage power source for the inputs though like 12v or somethuing ..i will have to look into this..im pretty sure the last mach3 bob i did on another cnc needed 12v to bob to power on the input section of the board............thnaks

[dazp1976]

thats what i may have to do...i beleive there is 5v feeding the opto so i can maybe use that 5v to power the bob logic..i do beleive though that the bob needs another higher voltage power source for the inputs though like 12v or somethuing ..i will have to look into this..im pretty sure the last mach3 bob i did on another cnc needed 12v to bob to power on the input section of the board............thnaks

Correct.
For the inputs and the spindle on/off & analog control.
Only the bob axis outputs run on 5v.

Can still be done for less than £20gbp for a Bob a 12v & 5v supplies.
Good cheap option. I used one for years.

[CNCMAN172]

Shelby,
The PC parallel port has never output 5V signals, it was always spec'd as a TTL interface, so 3.7 to 3.8v was normal for a high signal, and low was usually about .5v. What is wrong is your parallel port card does not contain pull up resistors and it is using open collector transistors to drive the output signals. Most basic BOB cards like cnc4pc c10R cards do NOT require a 5V power supply or any other supply. They pull the required voltage right off the parallel port. There card is $23, but you can select pull up resistors or pull down resistors.

https://www.cnc4pc.com/c10-bi-direct...face-card.html

Russ

[Shelby5041]

Ive got an old desktop pc power supply i can use and i have an extra bob...thats what i may have to do

[Shelby5041]

Thanks cncman...ill use a bob

UOTE=CNCMAN172;2506096]Shelby,
The PC parallel port has never output 5V signals, it was always spec'd as a TTL interface, so 3.7 to 3.8v was normal for a high signal, and low was usually about .5v. What is wrong is your parallel port card does not contain pull up resistors and it is using open collector transistors to drive the output signals. Most basic BOB cards like cnc4pc c10R cards do NOT require a 5V power supply or any other supply. They pull the required voltage right off the parallel port. There card is $23, but you can select pull up resistors or pull down resistors.

https://www.cnc4pc.com/c10-bi-direct...face-card.html

Russ[/QUOTE]