Making full use of the PMDX-122

[KenC]

Hi,
I bought a PMDX-122 for my Mechmate. Mainly, because almost everyone uses on for their Mechmate. This is the most expensive board during my sourcing so it better deliver as much as the manual said it would. Want to make full use of this board. BUT before I could get the best out of the BOB, I need to be sure I know what I want...

I want
1) E-stop that really ties with the BOB
2) PC controlled Spindle on/off
3) Charge pump features
4) PC via BOB to control Stepper motor Power Supply.
5) Limit switches (micro switches),with optional Zero proximity switch

My Micro stepping driver is a Leadshine M860, as the Gecko is not within my means.

This is by best wiring attempt so far, I don't think I'd done it correctly.
7309

Please comment freely and thanks in advance for the heads up.

Also attach the M860 user manual. & the stepper motor wiring diagram.

[Gerald D]

Ken, your main drawing is not entirely readable.

[Gerald D]

Copied from the other thread:

Normally the power gets connected to the top 2 points on J8. That bottom point is marked as an output.

Do you seriously want nine limit/home switches?

[KenC]

Hope this is better
7324

[KenC]

Copied from the other thread:


Do you seriously want nine limit/home switches?

Sounds like I'm over doing?? I blame it on overly safety conscious as I read of 500ipm travel...
The limit switches are USD0.90 a piece, good Japanese made Omron. When compare to proximity switch (US$15++), they are less accurate but I question the need for extreme accuracy. IMHO, for MM's application, the machine (0,0,0) position is set using zeroing technique for every single job, the sensor zero position is for parking purpose hence even a few mm off the mark won't hurt anything. BUT I can be wrong about this & I'm all ears.
7325
I have yet to buy all but 6 mechanical micro switch for now... 9 is for minimum academic consideration, each axis have an end limit at each end of the travel & a zero(parking) position. BUT if its not necessary, the surplus can go elsewhere such as door alarm, mouse traps... etc :D

[KenC]

Copied from the other thread:

Normally the power gets connected to the top 2 points on J8. That bottom point is marked as an output.

Thanks for the heads up, I'd edited the power input. Will post a fresh revision once the following are cleared.

1) will the E-Stop & limit switches scheme (J5 & J6) work correct?
2) I am not sure of JP1, JP2, JP3, JP5 & JP6.
3) Is it safer to let the PC to switch on the stepper motor power supply rather then having them power up all the time?
4) Is there anything else I missed out?

Thanks in advance.

[Gerald D]

Copied from the other thread:

You are overdoing the limit switches. For example, how do you detect when a cutter has gone too far in the z-direction? Suggest that you get a better understanding of Limit Switches - optical / mechanical / proximity (http://www.mechmate.com/forums/showthread.php?t=584) and see that all switches easily go on one series circuit (similar to e-stop).

[KenC]

Copied from the other thread:

Thanks for the lead, I did spend a considerable effort trying to understand that thread but still cloudy. Have to consider 5V (4.2V after the PMDX), debouncing. Therre are schemes to use relays, logics or even micro processor...

This limit switch thingy is holding up progress of my build, since the MM can operate without them, I would have to leave it out until I know what to do.

Now I need to find out more about Zero-plate, apparently this is essential.

[Richards]

Ken,

Section 7.2 of the PMDX-122 manual has a note about powering the board. You have +5vdc connected to J8-Aux power OUT. That may work, but it is not standard practice. Usually you would use J11 or PWR Alt In on J8.

I'm not clear on how you're using J7. Because it is normally open, the main contactor will not close until J7 switches; however J7 cannot switch if the contactor is not activated (the main contactor is in series with the other E-stop switches in your drawing).

I haven't checked signal polarity for your stepper drivers or PMDX-122 jumpering. (It's about 2:30 a.m. here in Utah and I'm getting blurry eyed.)

Edited:
Gerald, I just noticed your response on the other thread where you caught the +5VDC power input. You beat me to it again.

[Gerald D]

Mike, the sun favours those to the east of you - it comes up a lot earlier here! :)

[KenC]

Ken,

Section 7.2 of the PMDX-122 manual has a note about powering the board. You have +5vdc connected to J8-Aux power OUT. That may work, but it is not standard practice. Usually you would use J11 or PWR Alt In on J8.

I'm not clear on how you're using J7. Because it is normally open, the main contactor will not close until J7 switches; however J7 cannot switch if the contactor is not activated (the main contactor is in series with the other E-stop switches in your drawing).

I haven't checked signal polarity for your stepper drivers or PMDX-122 jumpering. (It's about 2:30 a.m. here in Utah and I'm getting blurry eyed.)

Edited:
Gerald, I just noticed your response on the other thread where you caught the +5VDC power input. You beat me to it again.

Thanks for taking your time to answer to my post.

Would you connect +12Vdc or 5Vdc to J8? This is one of those small issues which had been puzzling me...

I should had explain how my electrical schematic. will draw up one soonest.

My electrical schematic is identical to 10 70 115 A, I connect my PC's PSU parallel to the contactor. since
1)we all operate our PCs without a contactor in front of it,
2) with all the protection of these very modern 300W PSU
3) atom mobo running on thumb drive feeds on less the 10W, + all supply to PMDX122 is tiny, there will be a huge capacity headroom.

BOB takes its power from the PC PSU's drive power plug,
The spindle will have its dedicated power line from my main distribution box as 2.2kw (3hp) is about the limit of my power sockets.

In another word, I can power up my PC + bob independently, from here I control switch on/off both the stepper & spindle safely via EMC2.

I wish to have the J7 on N/O, in any case the BOB died, both the spindle & stepper will power down safely.

Hope to hear from you about my driver connection soon.


Thousand thanks

Ken

[riesvantwisk]

Ken,

I don't want to confuse you with more ideas, but this is what I am doing:

- I wire my control box according to Geralds schematic (10 70 115 C)
- On my control box I do add two Pull Reliefs for future cabl,es, properly teh limit/home switches.

The e-stop is done using Geralds Schematic, not using the e-stop on the PMDX, this because when I press the e-stop I want the whole thing turned off of the electricity making it a real e-stop, safety first! To power the PMDX I bought a 7VAC transformer and I connected it straight to the PMDX, so there is no need for a DC power supply.


My advice is to wire it up simple (10 70 115 C) for your first run. Then add the additional futures you need once the machine is running. This way you can concentrate on the build rather then on the nitty gritty details of electronica.

To add the limit switches you only need to drill in the metal, no need for welding so this can be done very well after paining.


Ries

[KenC]

Ries,
Thanks for sharing.

I will to keep it simple to get it moving. My concern at this stage is tomake enough extra pull cable holes, allow enough room as in physical space & sufficient I/O for the necessity. I had in the pass allocate space/resources in other projects through guess work & eventually turn out useless.

My power scheme sounded complex but it really isn't, with the PC integrated into the panel, I have an overly under utilized PSU sitting there staring at my face. & if there are needs for powering other accessories such as fans, proxy switches, relays, micro processors... etc you name it, the PSU can cater with ease. Hence no need to spend extra $ & space on tranny. And also I'll tap the power for the minitor from it.

Apologies for the poor qualit, wanted to draw a proper schematic but a free-hand sketch is so much faster.
7332
From here, you will see everything except the PC will turn off when any of the E-stops is pressed. and the PC & BOB are "informed of such action.

A separate power line for the spindle is out of necessity as my existing power line is rated at 15A each. so for safety, de-rate to 2.2kw is just about right.

[Gerald D]

I wire my control box according to Geralds schematic (10 70 115 C) . . . . .
The e-stop is done using Geralds Schematic, not using the e-stop on the PMDX, this because when I press the e-stop I want the whole thing turned off of the electricity making it a real e-stop, safety first!

Ries, under each of our e-stop buttons we have 2 contacts, for two separate circuits. The one circuit is according to 10 70 115C and the other circuit is the PMDX e-stop. (Those two circuits run in separate screened cables)

[KenC]

Brushed up a little on the 7335

[riesvantwisk]

ken,

how is your PMDX powered?

GErald,
In my case I used a transformer (9VAC) to power the PMDX. This transformer is connected after the relays. So when the e-stop is pressed, the whole box is out of power. This also should notify MACH3/EMC2 that the system is out of power. Am I correct in this?
This way I don't need to have two separate circuits... I think :)

Ries

[Gerald D]

Ries, the capacitors are still charged after the main power stops and this will keep the motors turning if there are still step/direction signals from the BOB.

[riesvantwisk]

Gerald,

I don't want to go to much OT here, please tell me if I do so....
My PMDX is wired according to schematic 10 70 115. That means if you press the e-stop, then the BOB will also be out of power thus preventing of any movement to the drivers, even though during the de-charging if the capacitors.

Obvious, there might be a very small time in the ms(10-100, wild guess) range untill the BOB is out of power because of it's own capacitor. Wouldn't this not be fast enough to stop the machine?

I do agree that wiring the estop also through the BOB will make the system stop faster.
My estops just came with one switch, not with two, may be this is why I just wired it only over the 115V side.

Ries

[Gerald D]

Ries, I don't know if the BOB is completely "safe" when power is removed. . . . for some reason, the BOB manufacturer supplied a e-stop connector, instead of just saying to cut the input power. However, I think that you are safe enough just to cut all power, I don't think that the capacitors will keep anything going for a long time.

[riesvantwisk]

Gerald,

this is exactly what I am thinking. Since the stepper need a pulse train, they will not rotate if there is no power on the BOB.

I personally find it even a bit dangerous to depend on a e-stop only with electronics. I have seen more then once in my electronics works that a digital circuit failed for any reason keeping a output high or low (depending what broke).

For this reason I am charmed by you e-stop circuit only needing a single relays, I know they under some conditions they can stick awell and this is the reason that I might add the e-stop on the BOB later on in time.

well though off....

Ries

[Richards]

Ken,

The PMDX-122 has an on-board voltage regulator that requires at least 8V. (I've used 9VAC and 12VDC power supplies with good results.) Section 1.4 of the manual states that you can use 7 to 12VDC on J8's Aux Power Input.

I'm still concerned about using J7's N/O contact (relay) as part of the contactor/E-stop circuit. Again, because I don't have a schematic, I don't know how the relay is driven. I'm guessing that a buffer chip on board amplifies the signal from the PC. If that is the case, then that buffer signal won't work unless the E-Stop circuit is closed and the E-Stop circuit cannot be closed until the on-board relay is turned on. In other words, you have a classic catch-22.

[KenC]

Richard,
You are right, at power up, the J7 is open & this will keep the E-stop circuit open hence the PMDX will stay in "hold" state & there is nothing I can do to change this state.
But it will work if I have the relay after the main contactor. Hmm... 2 relays in a row... doesn't feel & look right, does it?

Ries,
My PMDX is powered by the mobo's PSU. which is parallel to the stepper system PSU.

Garald, Ries,
Apparently, reading only the PMDX manual isn't enough to visualize the whole picture, out of desperation, I picked up the EMC2 Integrator Manual V2.3 on my desk & viola, I started to see a silver lining. :)

The E-stop on the BOB:-
This pin will inform the EMC2 program that there is a problem in the real world, it will tell the motor to stop moving & hold whatever its doing until the "all clear" is signaled i.e. resume "on". From here the EMC2 will resume from where it stopped & get on with the work.

In the 10 70 115, the PC isn't informed of the real world condition, it will keep sending signals and if the BOB didn't die at the instant E-stop is pressed due to its capacitor charge, instructions will still come through & the stepper motor will continue with the instruction until the capacitor charge runs out.

In the usual 10 70 115 configuration, once E-stop is pressed, all position info are lost & resuming the work will take some effort, not impossible with experience operator, just tedious.

PS, I base my logic on EMC2 but I bet Mech2 follows the same line of though as well.



As for the limit & home switches, EMC2 is so clever that even allows all the switches in series or parallel into one input pin. We are required to design the homing sequence to suit.

As for mechanical switch, there is a debounce function which I'll have to read more to understand.

A draw back of mechanical switch is that if I wire them in the normal position, I won't be able to detect car lifting.... but they are dirt cheap & trouble free.... hmm... need more thoughts...

[Gerald D]

I think that a lot of people expect too much from a BOB.....

Realise that a BOB is a Break Out Board - it "breaks out" the wires/cores of the parallel cable so that they are easy to use with Mach/EMC and the typical devices (lmit switches/routers/etc) found on a simple CNC machine.

A BOB does no signal processing, it does not have any processor chip, it is not loaded with a driver program, it has no memory. In fact , some people do not even use a BOB at all (they connect the parallel wires/cores direct to the stepper drives). All in all, a BOB is a very stupid device. It amazed me that PMDX could write such a long manual on such a simple device. The fact that BOBs manage sell for around $100 is because we are lead to believe that they are complex devices - and I think we should recognise that we might be mislead.

[KenC]

Aye! Aye!
Initially I was puzzle why the rage about the BOB but I went along with the crowd for confidant. Anyway, since I'd already took the plunge, it would be best to make the best out of it.

I now am sure that the purpose of BOB is to buffer the I/O signal & provide easy connection for those solder iron rookies.
As this thread grows, I recognized that I lack the knowledge to configure those parallel port pins.... That is ment to say that I'd been barking up the wrong tree....

Anyway, I am still not confident of the JP arrangement, if I'm unlucky, I may risk frying my mobo & drivers...

I would most appreciate to anyone taking a good look at my stepper motor connection & jumper settings and advise this electronically challenged paranoid?

Thanks in advance.

Ken


##PS,
The BOB set me back US$147 to my door step....

[riesvantwisk]

Ken,

I think there is a bit of philosophy going on also, some people considers a E-Stop a button to stop on which you later can continue, other really see this as an emergency stop.

In many cases, E-Stop means Emergency stop. Meaning to say, drop power as fast as possible on the complete box because something bad is happening, bad enough to ruin the work because life is at stake, fire in the motors, fire in the cabinet... whatever. This is the reason why people wire the E/Stop over the main power relays. Once pressed, work is considered lost, but life safed etc...

You will also often see two buttons next to the E/Stop (green&yellow) they are program start&stop buttons. They will inform the computer that he needs to stop executing, but it will keep power on the motors/BOB/drivers so that positioning information is not lost, I am going for this route.

I agree with Gerald about the BoB, it's a 20USD device sold for 100USD :s, but well.. it saves us time, also worth something.

Ries

[KenC]

Still stuck:mad:

Also tried to configure the EMC2, guess what, more stuck then ever... :o

[riesvantwisk]

Ken,

are you still stuck creating the schematic?

Ries

[KenC]

Ha3! I now have an error file that is longer then my family tree on top of my schematic situation...

[KenC]

Hi,
Took some time off to build some racks & a new bench for my new workshop to mellow down my earlier frustration with the BOB,
Here's the revision.
7827
further details,
I connect my driver opto-isolator as common-anode (NPN), set the COM on J1, J2, J3 & J4 of BOB as +5V power source to the Driver's Opto-Isolator by setting the JP1 to Pin 1-2. Decided to omitted the ENA function of the Driver for simplicity, the driver will alway be ready when it gets power. Charge pump will watch over it.
7826
I want the E-stop feature but not the fault, so I left the fault pin disconnected. and set Pin10 of parallel port as "ESTOP in" in EMC2.
I still want the charge-pump feature of the PMDX 122, so I configure Pin17 of the parallel port as "charge-pump" in EMC2.
The E-stop ring will be as show, using a magnetic coil relay/contactor to feed the E-stop pot at J6.
Leaving the limit switch & home switche details for later, but generally, all limits will share pin 13 & all the home will share pin 12.
Need a second opinion before I power up the kitchen table project...
7828

[riesvantwisk]

Ken,

I cannot ready the small attachment,
but when reading the dxf and your configuration it looks like you are good to go for your kitchen project.

This is what I did for my wiring:

- wire bob to gecko
- wire spindle/router relays
- wire 110V supply of everything before the main relays
- wire everything after the mains relays
- wire power transformer, rectifier and capacitors
- wire and other transformer (power supply BoB)
- wire capacitors to gecko
- wire door panel to main panel

Because the wiring can be confusing around mains relays, I first figured out what parts of the main relays to use and I put the relays numbers on my printer wire diagram. This would help me to follow better what connects to what.

For each wire/connection I did physically I used a yellow marker on each wire/trace so I knew what I have been wiring and what not.

wait a day..... (brain needs rest)

- Follow each wire again and check if all connections are correct.

Testing mains relays

- remove the wires of anything that outputs from the main relays (but not the holding circuit)
- apply power to cabinet and see if your on/of switches work and if the light in your office doesn't go out :)

Testing power transformer

- remove all power to the GEcko's
- re-connect your power transformer to your mains relays and re-check if your capacitors are wired correctly +/- of these capacitors is important, when a 10mF capacitors blows it will let you know violently.
- re apply power and check DC output voltage of the power transformer, turn main power of and see if you feel any heat, you shouldn't feel any heat at all...

Testing BoB transformer
- Connect BoB power supply to output of mains relays
- disconnect the BoB and test BoB power transformer, you should have 12VDC or 7VAC after mains is on

Now you are good to go to test the Gecko + Bob on your computer

TEsting computer + Gecko connection

- reconnect your gecko cooling ventilator
- re-connect one gecko drive to transformer
- re-connect transformer of BoB to BoB
- Connect parallel port BoB to PC
- connect a stepper to teh Gecko
- have you added the resistors to each gecko?

After you power on, you will notice that really nothing happens, the ventilator of the gecko will go on and on the BoB and gecko you will see some green lights

When using the tool of EMC2 to configure the parallel port you can also rotate each motors when configuring each axis The initial setting is set a bit slow, so your need to test at higher speeds (10mm/s if I recall correctly).

I hope this helps..

Did I miss anything?

Ries

[KenC]

Ries,
Thanks for looking over my shoulder.

Just rewired & tested the PSU.
7865

[lumberjack_jeff]

Ken, I have a PMDX-122, drivers like yours and EMC. It's a workable setup.

I can help with the basic kitchen table configuration.

http://www.mechmate.com/forums/showthread.php?p=25688&postcount=1

[KenC]

Thousand thanks Jeff!

Careless of me missing out your thread...

Would you care to share how you set your PMDX122 connection in EMC2?
Is my PUL/DIR interpretation correct? The non-manderin speaking world uses Step/Dir instead.
In EMC2 stepconf,
Step Time? is this the t2 in the driver manuals?
Step Space? the t3 in the driver manual?
Direction Hold? (Completely no idea)
Direction Setup? the default is 20,000ns, & now matter how much I change this. it will always go back to 20,000ns
I set the Leadscrew pitch to 9.422778, (1:1, 24teeth module 1 spur gear)

Thanks in advance

Merry X'mas

[lumberjack_jeff]

Hi Ken, and thanks for the Christmas wishes, I'll check my config tomorrow morning when I get out to the shop.

I will say that my initial "leadscrew pitch" setting came out way wrong. I eventually arrived at a setting by telling the machine to go to x=96 y=48 and measuring the actual travelled distance from x=0 y=0. I used the difference between 107.331 (the hypotenuse of a 48x96 triangle) and the actual measured result as a correction factor.

A couple of iterations of this will get you closer than any other method.

[lumberjack_jeff]

step time 2500
step space 2500
direction hold 20000
direction setup 20000

On the pmdx,
jp1 is set for +5v
jp2 is set for "always"
jp3 is set for "not estop/fault"
jp4 is set for "normal"
jp5 is set for "out"
jp6 is set for "normal"

BTW, my leadscrew pitch is .0321039 (7.5:1, 20 tooth pinion)

on the stepconfig wizard, I have the x steppers both configured as x with the checkbox marked "reverse" on one.

[lumberjack_jeff]

I've done some tweaking today trying to resolve some problems.

My step time is now 5000
step space is now 5000
dir hold is 1200
dir setup is 1200

Better, I think.