Problem with my Fanuc 18 cnc mill

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03-01-2023, 06:48 PM
puddi

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Problem with my Fanuc 18 cnc mill

Hello everyone, I recently purchased a used 2004 CNC 3 axes mill and it worked fine, then one day I got some "tank coolant HI" message and upon inspecting the sensor and its output I figured my PMC/PLC won't reckognize the input.

My jog functions don't work (altho they glow up and beep) and my EMG STOP button doesn't work either. When looking at ladder diagram in my PMC diagnostic screen when I press the EMG stop the line doesn't glow up as if it is not reading inputs correctly. Switches and sensors are okay and voltages are okay everywhere (24V). As I own another exact same machine I swapped fanuc input cards and nothing. I am affraid to swap further the cards with batteries as they contain parameters and other data I don't want to mess up. Can someone help me diagnose the problem?

I have attached a photo of ladder diagram in question. Can provide more photos and information if someone can guide me throu diagonstic steps.

Thanks for reading, Izidor
03-01-2023, 08:37 PM
the_gentlegiant

Re: Problem with my Fanuc 18 cnc mill

Maybe you know this already. Maybe not. An Emergency Stop circuit is about as basic as you can get. It is a Series circuit just like old Christmas tree lights were when one light goes out they all go out. E-Stops are easy to trace with an ohm meter and the power off, or power on and a volt meter. Start on one end and continue along until you find the break or loose connection. A lot of times all or a bunch of E-Stop connections are right next to each other on DIN rail terminal strip. Your electrical manual can help show you where to look.

The coolant high thing sounds like a poorly working coolant float switch. (If there is such a thing)
03-01-2023, 08:49 PM
puddi

Re: Problem with my Fanuc 18 cnc mill

Thanks for the reply. Thing is the signal is white colored so that means EMG is not engaged. It is just additional information that I have that the EMG switch is not registering as an input here. And coolant sensor is fine I double checked, I am thinking my controller is not detecting inputs properly. It should detect when I press EMG button and it should detect the tank sensor but its not. My jog is not working nor any programs are working. I have no idea what to do.
03-01-2023, 08:50 PM
servtech

Quote:

Originally Posted by puddi

Hello everyone, I recently purchased a used 2004 CNC 3 axes mill and it worked fine, then one day I got some "tank coolant HI" message and upon inspecting the sensor and its output I figured my PMC/PLC won't reckognize the input.

My jog functions don't work (altho they glow up and beep) and my EMG STOP button doesn't work either. When looking at ladder diagram in my PMC diagnostic screen when I press the EMG stop the line doesn't glow up as if it is not reading inputs correctly. Switches and sensors are okay and voltages are okay everywhere (24V). As I own another exact same machine I swapped fanuc input cards and nothing. I am affraid to swap further the cards with batteries as they contain parameters and other data I don't want to mess up. Can someone help me diagnose the problem?

I have attached a photo of ladder diagram in question. Can provide more photos and information if someone can guide me throu diagonstic steps.

Thanks for reading, Izidor

Fanuc has an I/O module mounted in the electrical panel between the PLC (PMC) and input switches and output relays, the modules isolates the PMC to prevent direct shorts and damage.

I have had several of these go bad over the years, they also have built in micro fuses to protect the output.

I have had several of these modules develop dry joints and other faults so not transferring inputs or outputs.

Depending on the version, some have an F led indicating a blown fuse.

Missing inputs could be a bad module if they are related addresses
03-01-2023, 08:55 PM
puddi

Re: Problem with my Fanuc 18 cnc mill

That sounds like it might be the issue, can you help me locate the IO module? Is it like a PCB inside the display housing or is it one of those Fanuc yellow boxes?
03-01-2023, 09:00 PM
puddi

1 Attachment(s)

Re: Problem with my Fanuc 18 cnc mill

I have another identical machine and I replaced the middle and the left module/boards on the picture, right one has battery so I am affraid to remove it it might lose data.
03-02-2023, 07:14 PM
memoryman

Re: Problem with my Fanuc 18 cnc mill

The modules would be in a separate housing and are much smaller. You may have an I/O board in the main chassis. More photos are needed.
Did you check the status of the EMG signal in the DIAGN screen?
03-02-2023, 08:22 PM
servtech

Quote:

Originally Posted by puddi

I have another identical machine and I replaced the middle and the left module/boards on the picture, right one has battery so I am affraid to remove it it might lose data.

They are separate, usually near the bottom of the panel above the long terminal strip of wires.

A rack of small Fanuc boxes side by side.

Don't remove the boards you posted the photo of.

Take a photo of the whole panel and I'll point them out:-)
03-02-2023, 09:03 PM
servtech

Quote:

Originally Posted by puddi

I have another identical machine and I replaced the middle and the left module/boards on the picture, right one has battery so I am affraid to remove it it might lose data.

This is a fanuc I/O there are different types depending on the age of the control.

https://www.ebay.co.uk/itm/115169176302?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=lUjOJjihQNu&sssrc=2349624&ssuid=OwNaGgfuTa K&var=&widget_ver=artemis&media=EMAIL
03-03-2023, 04:49 PM
puddi

Re: Problem with my Fanuc 18 cnc mill

I found nothing like that in my machine, only the boards I sent photo of, the leftmost board has IO written on it and there is 4 ribbon cables going into it and I confirmed they are indeed used for inputs and outputs. My diagnosis screen tells me nothing about the errors, there is only EMG flashing on the screen when I power up the machine and it goes away when I press EMG reset pushbutton. On my ladder diagrams I checked some signals from sensors on tool changer and they work (the lines glow up green or white depending if sensor is activated or not) but sadly nothing changes when I press my EMG STOP button like it doesn't read the signal right. All switches are tested and working.

When I press JOG on operator panel the system indeed enters JOG mode as displayed on the LCD screen but nothing happens when I actually press the axis move buttons. Also when I input a single line of code in MDI mode and press CYCLE START button program simply doesn't go into execution. I have masters in electrical engineering so feel free to recomend any invasive fixes or diagnostic methods as I am feeling kind of lost, nothing I tried makes no sense.

I have another identical machine and I swapped IO cards with that one and didn't fix it, on other machine stuff works with both boards. I am a bit of replacing all the boards as some of them might lose memory or something so please do advise me on what to do.
03-03-2023, 05:27 PM
memoryman

Re: Problem with my Fanuc 18 cnc mill

First, make an SRAM BOOT backup, as explained in the manuals.
Where are you located?