Messages

1711

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 11:35:45 PM »

Hi,

Does it appear to you that I have not toasted the photodiodes? given the measurements I have listed above.

No, I think they are OK. Delta is a good brand and while its not impossible to blow them up they are well designed
and do not fail as a result of the usual misadventures they suffer.

BTW, I was careful not to short out the internal 24dc like I did before. I thought the clicking sounded 're-set-ish' and so I pulled the meter leads after short observation. fortunately the protective circuitry appears to have saved me.

I agree, and am glad because it was my mistake the induced you to do it. I think this is a case in point of what I mean above. Delta has made design
provision that the supply could be shorted WITHOUT causing failure where another cheaper brand may not have.

Delta drives are not hugely expensive but I'm sure I don't want to damage mine any more than you wish to damage yours, so it behoves
us to be a little cautious about wiring them up.

I will draw a circuit diagram that may hopefully clear up some of the confusion.

Craig

1712

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 07:44:21 PM »

Hi,

Checking the Resistance withg the 20Ohm scale on my meter with Com correct and the Red probe connected to the 200mA, when I check resistence I get 1.28

I think this is in line with your prediction of under 2Kom

This does not make sense.

One multimeter lead should be in the COM socket and the other lead in the V/Ohm socket with the dial set to 20 kOhm scale. Please repeat the
measurement and confirm the connections to your meter.

Craig

1713

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 07:41:42 PM »

Hi,
the photodiode is part of the opto-isolator of the pulse input circuit of the drive. When the photodiode is illuminated the phototransistor
is turned on and a pulse is signalled to the drive. Note that it is light signalled, there is no electrical or galvanaic connection to the internals
of the drive. This is to prevent a voltage mismatch at the input damaging the drive logic and microprocessor. That terminals provided
to the photodiode allow for included resistors when using single ended 24V signalling and much lower resistance (50Ohm approx.) when
using 5V differential signalling.

The only downside of having the two options id that you could miswire the inputs and therefore apply 24V to the photodiode WITHOUT the
benefit of the larger (2kOhm) resistors and thereby damage the photodiodes.

Believe it or not single ended signalling is much easier to understand and implement....and you should definitely do that BEFORE you attempt
differential signalling.

Craig

1714

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 07:29:47 PM »

Hi,

No you don't!. Delta drives are INDUSTRIAL grade, they are intended for 24V inputs, excepting differential modes.....but we are not talking
differential modes here.....we are talking single ended.

I'm sorry I've just re-read your post and YES you are correct, the transistor I have depicted allows your 5V BoB to turn on and off the 24V
photodiode circuit.

Craig

1715

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 07:26:05 PM »

Hi,

Do I have this somewhat correct?

No you don't!. Delta drives are INDUSTRIAL grade, they are intended for 24V inputs, excepting differential modes.....but we are not talking
differential modes here.....we are talking single ended.

Your BoB is 5V output as is common with hobby grade controllers...and a 5V output is not going to work on a drive that is expecting a 24V
input. That is the true purpose of the discrete transistors in the diagram that I posted. The 5V bob output via a 1k (approx.) resistor to the
base of an NPN transistor will be any amount enough current to turn the transistor hard on. The transistor when conducting hard on will
cause the current to flow from pin 37 to pin 14 and thereby illuminate the photodiode.

You need six transistors, say BC 547's and six 1kOhm or 1.5kOhm resistors for a three axis machine. You could alternately use 2N7000 MOSFET's
which would not require the 1kOhm resistor to make it even simpler. I would recommend a little vero-board or similar to solder it together.

Craig

1716

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 07:11:58 PM »

Hi,
just to confirm you are using the 200mA scale. The measurement you are taking has nothing to do with resistance, its a measure of
current.

Usually there are three, maybe four input sockets on a multimeter. The Com, is the black one. The V/Ohm red one is to the right.
The two current input terminals are to the left, one (fuse protected) is up to 200mA and the other, depending on the model is not
fuse protected and up to 10A

One multimeter lead should be in the COM socket and the other in the 200mA socket with the selector dial on 200mA DC.

It sounds like you are reading 22.8mA, which is good news as it suggests that the photodiodes are intact.

Just as a comparison please put the multimeter lead from the 200mA socket to the V/Ohm socket and with the dial set to 20kOHM
measure the resistance between pins 35 and 37 with the drive de-powered. I would expect a shade under 2kOhm.

Craig

1717

Mach4 General Discussion / Re: New to jogging/ non g-code moves

« on: February 05, 2020, 04:37:03 PM »

Hi,
your proposal sounds simple but it is in fact not so easy at all.

Lets say you have a Gcode move be it from a Gcode program or MDI, Machs trajectory planner will issue PVT (Position, Velocity over Time)
data in 1ms slices. This numeric data will be put in the buffer to be 'consumed' by the motion controller at the rate of one data set per millisecond.
Typically the buffer in Mach4 is around 200ms. The default setting with the ESS for instance is 180ms.

Lets assume for the purposes of this discussion that the buffer has 100 data sets or 100ms worth of moves stored up. At that instant your input 'a'
changes state and now you wish to change the trajectory of the machine. If you abort the trajectory data within the buffer then Mach has lost reference,
a bad outcome. That would be like an Estop. Even assuming that you could abort the pre-existing data sets there would be a time when the motion
controller had no fresh data sets to consume so it would be stationary which rather violates your intention that the y axis progress smoothly
while there may be a variation in the z axis.

The type of motion you want is actually very similar to THC used on plasma tables. A plasma table has typically a succession of 2D moves
in X and Y as it traces out the shape of the part but the Z axis will go up a bit or down a bit to maintain a near constant arc voltage. This has
to be achieved WITHOUT affecting the smooth motion of X and Y and must not cause Mach to loose reference.

THC has, until recently at least, been enacted by the motion controller as the motion controller works in realtime whereas Mach does not.
Even then only two Mach4 ready motion controllers have that feature, the Hicon Integra and the ESS. More recently NFS have released
a scripted version of THC which does not require realtime support on the behalf of the motion controller. It is very much slower to respond
but is none the less adequate for a good many plasma tables.

May I suggest you look closely at the THC feature of Mach4 to determine whether you might adapt it to your sanding machine.

The only other option that I can think of, dare I say it, is LinuxCNC. LinuxCNC is a realtime computing system and does not have a buffer
as Mach does. This results from the fact that LinuxCNC runs on a realtime capable version of Linux. Windows PC's are not realtime capable,
at least in any practical sense, and thus ALL Windows CNC solutions including Mach, UCCNC, PlanetCNC, WinCNC etc require a buffer.

Craig

1718

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 02:59:25 PM »

Hi,

I have tried reading across pins 35 and 14,  and I get nothing until I hit the 200mA range and then the drive clicks

My apologies, I did specify pins 35 and 14, but I meant pins 37 and 14. By using a ammeter from 35 to 14 is effectively shorting the internal power supply
to 0V, please don't do it again. I'm hoping that the reducing current is an overcurrent limit device within the drive.

Follow the circuit of the picture:
pin 17= 24V output to pin 35, through the resistors and photo diode to pin 37, through you ammeter to pin 14 0V return.

This brings me to the question of the resistors. I am not clear on where the resistors are in the real world. are the 2kohm and 75 ohm resistors contained in the asdab2 drive?

Yes they are. My bum steer (pin 35 rather than pin 37) might lead you to believe they are not in circuit but if you retest but with the correct pin
you will 'see' the resistance. Again my apologies....measure the current between pins 37 an 14 for the direction photodiode and pins 41 and 14 for
the step photodiode.

I would not worry about transistors until you have established that the photodiodes are intact. Any small signal NPN transistor will do,
I used BC547's. Even a small MOSFET like a 2N7000 would work.

Craig

1719

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 03:35:57 AM »

Hi,
sorry forgot to attach the picture.

Craig

1720

General Mach Discussion / Re: Mach3, Delta ASDA-B2, ESS. 12 straight hours working on this. could use assist..

« on: February 05, 2020, 03:05:05 AM »

Hi,
referring to the attached picture from 3-27 of the manual.

Note that the internal 24V power supply is available at pin 17. Following the diagram you should direct connect pin 17 to pin 35.
With pin 35 now at 24V current can pass through the approx. 2kOhm resistor the 75 Ohm resistor, through the photodiode, through
the second 75 Ohm resistor to pin 37 and thence to the 24V COM at pin 14 via the transistor switch of your BoB or input circuit.
There is a second current path through the 2kOhm parallel resistor as well.

You can test the photodiode by having pins 17 and 35 connected as above. Then with your multimeter in ammeter mode probe
between pin 35 and pin 14. If the photodiode is intact I would expect a current of (24-2)/(2000 +75 +75)=10mA plus another
24/2000=12mA being the current through the 2kOhm parallel resistor, for a total of 22mA. If the photodiode is open circuit
you'll see only 12mA.

Note that Delta have an anti-parallel diode across the photodiode. This prevents a large reverse bias from ever being presented to the photodiode.
Photodiodes are notoriously poor at resisting reverse bias, they tend to go into destructive avalanche breakdown, hence the anti-parallel diode
is precautionary. You can test it in identical manner to the photodiode. Connect pin 17, not to pin 35, but rather pin 37. Now with your multimeter
still in ammeter mode probe between pin 35 and pin 14. If the anti-parallel diode is OK you should see about 22-24mA. If its open circuit
you'll see only 12mA.

I bought three 750W B2 series and drives, brand new, for $520 each (including $80 three day DHL shipping to New Zealand) several months ago.
In short you should be able to buy a NEW driver for around $200 plus shipping. I wouldn't be messing around with second hand at that price.

I am seeing applications for as servos/drives everwhere now.

Modern AC servos have such a wealth of control options, including step/direction position mode, analogue velocity and torque modes, a variety
of index modes (position and velocity), and secondary modes as well. Thus you could have your servo running in position mode as its primary function,
yet by controlling one digital input to the drive, it can switch to velocity mode. They are just so flexible they can be used in so many circumstances.

To date the price of AC servos have prevented many hobbyists from experimenting with them but Delta and DMM are two brands of GOOD quality
at very fair prices. There are even cheaper Chinese made servos and drives and while less is known about the quality and backup of these
cheaper brands many who have used them are reporting good success. Over the coming years more and more hobbyists are going to take advantage
of the performance benefits.

Craig