Got my MR-J2S40 Mitsubishi servo drives turning and a few questions..

[CncForMe]

Yup all 400 watt drives mostly because that is what is easily available. This machine is dual purpose plasma router, and yes there are a lot of negatives with a mixed use machine but that is really what my shop needs. Maybe in the future I will make a table for plasma and just use this for routing. The gear boxes are Thompson micron ultra true 7:1, 9:1 would have been better but I have NO issues with power or resolution. I got an amazing deal on them $70.00 each for four used but look almost new. New retail $1600.00 EBay is great. I even got one of the drives MR-J2S-40A for $45.00 shipped!

The hardest part of the whole machine is getting the rails straight and level. First I tried self leveling epoxy, almost worked but the surface tension didn’t let it level over the almost 12 feet. So I came up with this set screw idea now there are 160 1/4-28 thread set screws under the 8020 (t-slots). The plan is to take a machinists level everywhere when all is finally built.

[CncForMe]

Man pics load slow to this site, of course it is free!

[macona]

If you put a 24v signal directly in to the step and direction pins you WILL fry the input of the drive. I know. I found out the hard way. You can send 5v right into the step and direction pins. My lathe is making chips right now with direct connections from the breakout boards to the inputs on the mitsubishi drives.

The 24v supply is current limited in the drive to limit the current to the optos on the step and dir pins. The best way to run these drives is with a line driver.

-Jerry

that should of been parameters 3 and 4 for gearing!

(still have trouble getting my head around working it out after a few beers)

if you are using the setup software and have the same ratios on all drives you can simply plug the communication cable in and "write al"l to each drive

thats how i set up drives i sell for people and test on my rig before sending out

(the reverse polarity solution i havnt tried as i had already wired the chip into rig. but as the drives want 24v and as thats what the manual shows thats how i advise people to do it. so its really easy to fault find in the future as its easy to check both the 5v signal in and a 24v signal out)

[battwell]

macona. your running mr-j2 series?
the solution doesnt appear to work with mr-j2s series hence the 2803a chip.(unless i overlooked something whereas il stand to be corrected)

i have wired h, j , j2 and j2s series drives this way. (the h series will also run direct from 5v line driver but it makes my interfacing non standard. it aalso allows for a very easy to access test point for both input and output signaling



the 2803 chip is widely used in my main buisness for different input levels (pinball machines and automatic vending equipment) hence having them here and using it as a solution on the first one i did. not saying its the best way but its very simple and works as described. i wrote the pin to pin wiring and main parameters for cnc for me and he had his first axis up and running the same evening.

[macona]

I am running the MR-J2. I have a J2S and have popped it open and the input circuit is virtually identical, just slightly more modern version of the components. The pins on the 3M connector feed through a small resistor and directly into the opto isolator. There is a reverse polarity protection diode in parallel with the opto. When you jump the internal 24v power supply on the external connector it brings the power back in and branches off to the two optos with a current limiting resistor for each to the positive side of the opto (NG, PG). So when you use a 2803 to ground the negative side of the opto (Pins NP, PP) to signal ground current flows from the 24 internal source, through the current limiting resistor, the opto, the 2803 (Or any other switching device) and to ground activating the opto.

I believe the problem people are having is they look at the wiring diagram example where the controller is feeding pulses into the control for step direction. On the drawing NG and PG are going to the outputs marked - and PP and NP are going to the outputs marked +. So you try to hook up NP and PP to +5v signal and ground PG and NG and nothing happens. You check and there is current flowing so why is it not working? Because the current is flowing through the reverse polarity protection diode.

So if you want to use a Mitsubishi servo with step and direction off of 5v signal connect NP and PP to ground and +5v signal to NG and PG. Works great for me. There is a small resistor in line with the opto with a value of about 92 ohms. so there is current limiting. Somewhere around 35ma at 5v I figure. A tad high but it seems to work fine. I cant remember the opto part number but I think it was rated up to 50ma.

There is a simple schematic of the input circuit on page 3-40 of the MR-J2S manual. It is identical to the MR-J2.

[battwell]

just read your post. looked at schematic. now i see where your coming from!

i am using sg as ground, running as open collector input to np pp.
leaving ng pg open and floating. with a 24v input signal from the 2803a chip

your using the both sides of the differential input to switch at 5v.

(your right. the manual could be better too on the input signal variations)

im going to check out both methods tonight and check current draw etc.

seems there are a few ways to get these things to do what we want!

[CncForMe]

Well as far as the motion control aspect. Here is a silly utube video more to come. Pics tomorrow.


"http://www.youtube.com/watch?v=lOkZ3l1CDuk"]YouTube - CNC Machine

[thisguy]

Video of the machine cutting with plasma to come...

[battwell]

looks like your getting there!
time to find lots of scraps now to turn to dust and cut holes in!
took me a few months to get my biesse to stop making firewood and saw dust.
how accurate did the circles come out using the gearboxes on the rack/pinion?

ps i like the yellow legged spider in your control cabinet...2803a

[jorber]

just in case you havnt come accross this yet. the mitsubishi drive is looking for a 24 volt step/direction input not 5v

i tried feeding it with 5 volts into the interface but it wouldnt have it.

i used a uln2803a chip fed with 24 volts accross pins 9 and 10 (pin 10 24v pin 9 common)
inputs into pins 1 to 8 give outputs on pins 18 to 11 (opposite one to one so nice and easy) works perfectly at all frequencies i tried.
using mach3 and 100 steps per mm i can get 15000 mm per minute which is as fast as my commercial cnc. (ive set up electronic gearing in the drive)


with the 2803a chip you need no other circuitry, pull up resistors etc its all in there!
having 8 inputs and outputs one chip is good for 4 axis.
hope this helps anyone else.

I have a control similar to that siemens, did you use the smooth stepper
and a BOB to interface with MACH3? I see that in my control I need /step-step and /dir-dir and i only found breakout boards that their inputs are only S&D and comm or +5v How can i solve that? thanks

[battwell]

most drives can be set to step and direction in the drive parameters. i dont know your drive so you will have to read the manual.
no need for smooth stepper as you can change the electronic gearing in the drive to increase the speeds by dividing number of encoder counts by input frequency per mm etc

you can use any break out board. cnc4pc make one now with 24v logic instead of 5v if required

[battwell]

update.
post 27/8/09 by macona.
indeed this method does work on mr-j2 and j2s series drives!
so you can run directly from 5v break out board.
the h series doesnt work like this as you have to use different inputs for step/direction (so 2803a chip is still required) i have these running on my cnc d bench drill. (try finding interfacing plugs for h or first j series! not made by
3m but honda. like rocking horse poop. !)

[simpson36]

I am making the foray into commercial drives and to get my feet wet, I purchased a Mitsubishi MR-C20A and HC-PQ23 motor combo to play with.

To interface with Mach3 and a typical 5V BOB, I made a little PC board that converts the BOB's 5V Step and Direction signals to differential for direct connection to the Mistsubishi drive. This is better for noise immunity and solves the voltage issue as well. It is working great. The same setup should work on the MJ2S drive, which I am thinking about trying out next.

There is a 400 watt version of the MR-C, but the MJ2S seems to be a higher end drive. Can anyone shed some light on the differences?

[battwell]

the main differences are much larger encoder resolution and voltage choice
also encoder following for slaving etc etc
i only use mr-j2 or j2s now as they are great to work with and as accurate as you will ever need !

no need for fancy boards either, the mr series will work step/direction direct from 5v bob no problem! (just use a 2803a chip if you want to use the limits, enables etc to boost the signals to 24v. see previous posts)

[simpson36]

Thanks for the fast response!

I had the drive already connected and working in the manner you mentioned, but I decided to play around with the differential interface . . just for the heck of it. I already had the board design from a previous project which required the conversion for an encoder, so I just made up another board for the Mistubishi drive. A little extra noise immunity never hurts.

Couple more Q's if you don't mind:

What is you application for the drives and are you using the auto tune function?

If so, what is your opinion of it?

[battwell]

[nomedia="http://www.youtube.com/watch?v=RWa0IyNdbzA&feature=channel"]YouTube- MOV00181.MP4[/nomedia]
(using older h series drives)

[nomedia="http://www.youtube.com/watch?v=7E-TmwYuJNA"]YouTube- boxford-tcl125servo-repeatability.MP4[/nomedia]
(mr-j2s drives)

auto tuning is great (just jog a few times and its done. as you can see from videos. accuracy isnt going to be an issue.

doesnt compare to my latest conversion using the old drives though.. lol

[nomedia="http://www.youtube.com/watch?v=Gaj45i-FGnY"]YouTube- Biesse conversion. Last hurdle jumped![/nomedia]

[simpson36]

Thanks again for the fast response. You can see from this video that accuracy and speed are not problems.

[nomedia="http://www.youtube.com/watch?v=r9Zf_5yHB1I"]YouTube- Mini Machining Center Ruting and Drilling PC boards Rev2[/nomedia]

What I am after is a better method of driving my 4th axis and I seek an automatic method for engaging the spindle lock.

[nomedia="http://www.youtube.com/watch?v=sC2urdg_bqg"]YouTube- New Super Duty 4th Axis Rotary Engraving on mini-machining center[/nomedia]


I am pretty impressed with the feature set of the little Mistubishi. One thing it does not seem to have is the ability to return to a previous location after disabling the servo. It does continut to track the encoder, but does not retutn to the pre-disable position.

Is there some method of doing this with the MJ2S?

[battwell]

yes if your using mach 3 etc write the encoder trace to a dro. read the dro when you restart? fit the battery and the encoder becomes absolute so it knows where it is at all times.
if you dont use reset error on reset it will return.

you can also home to the index pulse, which is dead accurate. ie go to home switch, back off and find next index pulse. that way homing is always spot on regardless of switch accuracy. with j2s this is something like 1/32000 of a degree of motor angle

just looked at your pneumatic lock video. wouldnt be required with a mitsi.
also you can switch between position control to speed control for lathe using 1 input on or off. no dither to worry about!
the dither you have is caused by incorrect servo tuning. any servo should be tuned not to move unless commanded

[simpson36]

Interesting idea using the DRO in Mach.

The next step in the 4th axis development is a trunnion table. This is what the 'Super Duty' version is designed for. Dithering aside, there is always going to be some elasaticity in the belt drive which will translate into enough movement of the spindle to cause finish and/or accuracy issues in certain applications, therefor the spindle itself must be positively locked. The video was the first iteration of the idea. The current lock is far more robust and causes a complete hard lockup of the spindle.

Since these 4th axis are sold to customers with a variety of systems, uncoupling from a specific Mach feature is a design goal.

For example, in order to not rely on the Mach3 'swapaxis' function, I developed an interface board the accomplished the same task in hardware. That function is now completely transparent to the CNC control.

What were you using prior to the Mitsu and how would you compare the two?

[battwell]

ive used a lot of yaskawa too. just as good but you have to add a seperate 24v psu.

ive tried several makes but the mitsi have all the features you need in one drive.

yaskawas etc are drive model specific. but anything is better than a stepper!