[SRT Mike]

I have a 1995 Leadwell V40 with a Meldas M50 control.

Last night, the machine errored with the code "M01 OPERATION ERROR - 0101". According to the manual, this means the control doesn't have an operation mode selected (i.e. jog, handle, MDI, memory, home, etc). They suggest checking the switch.

I called Mistu and he had me go into the diagnostic screen and check the X100 memory value... when I change the switch on the panel between the different modes, I see the X100 value change each time. He said 3 bits of this number should change, but I am only seeing one bit change. 3 bits changing doesn't seem right to me... it's an 8 bit number and in each of the 8 mode switch settings, 1 of the 8 bits is 1 where the rest are all 0's.

Anyway, I checked the switch itself and I don't see anything wrong with it. The Mitsu rep said most likley the problem was "in the ladder" and I would need to contact Leadwell.

Leadwell say they could send someone up, but I'd be paying the plane ticket and hotel just to look at it.



What is the ladder? It isn't described very well in the manuals... it sounds like a series of checks that the machine builder programs into the control like "check if door interlock is open, if so, go to step to, if not, error... then check if coolant switch is on, if so.....". Is that about it? Or am I not understanding what it is?

The Mitsu rep said I should check the ladder documentation and go through it. I don't have any ladder documentation that I can find. I have en electrical manual for the machine, but to me it seems that it is getting the mode switch signal, so I don't understand why it's telling me it can't operate because no mode is selected.




Any help?

[Al_The_Man]

You can display the ladder on an M50, even edit it if you want. F0 key.
The ladder is the logic that controls general machine operations such as tool changer etc and all external switches and relays and communicates back and forth to the CNC side.
The function switch normally goes to 4 inputs for a total of 16 selections in binary.
If you are only getting one bit change on the screen it would indicate either the switch is not outputting the correct code or the inputs are defective.
The manuals and possibly the PLC manuals are on the MEAU website.
The one for editing the ladder is 'PLC ONBOARD INSTRUCTION MANUAL'.
The ladder display is especially usefull as it can tell you where a machine control problem is.
Al.

[SRT Mike]

You can display the ladder on an M50, even edit it if you want.
The ladder is the logic that controls general machine operations such as tool changer etc and all external switches and relays and communicates back and forth to the CNC side.
The function switch normally goes to 4 inputs for a total of 16 selections in binary.
If you are only getting one change on the screen it would indicate either the switch is not outputting the correct code or the inputs are defective.
The manuals and possibly the PLC manuals are on the MEAU website.
The one for editing the ladder is 'PLC ONBOARD INSTRUCTION MANUAL'.
The ladder display is especially usefull as it can tell you where a machine control problem is.
Al.

Al,

As usual, you are an incredible wealth of knowledge - thank you!

And here's an update... I tested the switch and it was OK. So I was flicking the switches on the control (block skip, coolant) and making sure they all registered in the diagnostic screen - when I hit the EMG OVERRIDE switch, the M01 error went away.

Hmmm...

I let it go, and the error came back. So I held it in and put the mode switch in handle mode to see if I could jog the axes, and I could. Then, after jogging them, the error returned when I relased the switch. I called Mitsu back, and while I was on the phone with the guy (about 5 minutes after jogging the axes), the error just went away.

I mentioned this to the Mitsu guy and he said that there's no way to tell (other than the ladder) what Leadwell hooked into that mode switch that could be generating the error. He said to go through the ladder and see what various things are tied into the X100 control line, and check them all and see if I can find anything - and if not, when it happens again, track test each line again and see which one is giving the signal to the control.

Sounded good.

So I fire up my program again, and at exactly the same point, it did it again... it does a toolchange to grab a face mill, as the spindle is speeding up and the spindle is moving down in Z (I think the XY motion has completed, but not sure), it gives the error. So something in my NC code is making the machine do something which is causing this error.

The ladder documentation (I found it in the manual with the help of the Mitsu guy) is really bad... it's barely legible. So I'm going to have a very close look at my NC code and see if I can figure out what I am doing wrong. I had thought that since the tool in question was a face mill that was right at the max diameter the machine allows, it may be a spindle load error or something since I'm trying to accelerate it up to 4500rpm. But I'm thinking it's something else.

I'll look through the code and I'll see if I can decipher the ladder documentation in the manual to see if I can get anywhere.

But does the above shed any light on what I may be looking for?

strangely, this problem has happened a few times before... it always just seemed random. I'd shut off the machine and the next day it would be OK. It always seemed to happen in the beginning of a cycle start, never mid-way through.

I bet when I figure it out, it will be a "duh" moment.

Thanks again Al!

[Al_The_Man]

The ladder is written by the OEM, in this case Leadwell, so things can be set up and programmed for different machines.
What form does the EMG Overide take? is it a button you push in to overide overtravel's or?
Can you tell if it goes into an input or is it a hardwired function?
Did you record the mode switch pattern when it was working?
It almost sounds like you have a intermittent power issue on the 24vdc supply.
It makes no sense that the EMG overide should be tied into the function switch.
Al.

[SRT Mike]

Well, figured it out.

It was the Y limit switch.... why it ties into that particular line I have NO idea. It makes no sense, but that's what it is.

The EMG override is just a toggle switch that temporarily allows axis movement even when the machine is on the limit switch... we did have problems with the Y limit switch before, where it's located, it tends to occasionally get a splash of coolant on it... this dries and turns gummy... and happens over and over, making the switch "sticky". So I think the reason the error disappears after a while is that once I move the table off the switch, it eventually pops back to it's non-tripped state on it's own, which kicks the control out of the error code.

Strange, but true.

I'm not sure how the other axes are tied in - for all I know, they would produce the same error code, probably do actually.

Thanks for the help!

[chippy1]

Actually, the EMG overide is just a jumper over all axis limit switches. If you look at you wiring diagram you should be able to see this. I would say what happened was the y-axis switch was actually shorting your 24 volts which is what is needed for your operation panel. Once you pushed the EMG overide you canceled the short or bypassed it.

Just my two cents

Chippy