Fanuc 6T. How to reinitialize the memory

[starn36]

Hi

Recently, i got the 998 alarm (A ROM parity error). I decided to try to clear the memory by doing 0+delete+power on. I also did cancel+delete+power to clear parameter(I made a backup on my pc). After that i got some servo error.

I'm not able to read my parameter now. I think it's because I'm not able to set my communication parameters because the controller is NOT READY. I'm in trouble.

I resolved some error by entering some parameters manually.

The only error now is 210 alarm (X+ OT)

Can you help me please to restart my parameters and help to understand my memory problem.

Thanks

[Dan Fritz]

You should be able to reload your parameters from your PC if you manually enter a few parameters for the serial port. For example:

Parameter 002, bit 5 (the 6th bit from the right) Turns on the serial port option
Parameter 003, bit 3 (the 4th bit from the right) Turns on the ISO code option
Parameter 311 (sets the baudrate, stop-bits, and handshake method for serial port)
Parameter 340 (input device)
Parameter 341 (output device)

Normally I set parameter 311 to 11001001. That's for 4800 baud, 1 stop-bit, and Xon/Xoff handshaking. These parameters can be added with the E-stop button pushed in.

On the SETTING page, set the PUNCH CODE to "1" for ISO, then set INPUT DEVICE 2 to a "1". You may have to release E-stop to change this setting. You'll need to be in MDI mode, display the SETTING page, then cursor to the item you want to change, press "P" then either "1" or "0", then INPUT.

With those settings you should be able to download your parameters from the PC using some DNC software.

To read in the parameter data, get your DNC software ready to send the file then, with the E-stop button pressed, turn on the Parameter/Enable switch on the main PCB, press the PARAM key to display parameters, then press the letter "P", then "-9999" then READ.

The Fanuc system 6 controls have EPROM chips for the main executive software, and some additional EPROMs are added for certain options. The ROM parity alarm you got was indicating that one or more of the EPROMs was either bad or missing. This can happen if you try to put an option parameter into the CNCs memory when the matching EPROMs for that option are not installed, or if one of the EPROMs is coming loose in its socket. The 6T-A control had several rows of EPROMs on the main board, but the 6T-B control has a separate "ROM" board with all the EPROM chips. Whichever one you have, be sure that they're all well seated in their sockets. Sometimes, after many years of hot/cold cycles, the EPROMs can actually back out of their sockets. Applying firm thumb pressure to each chip to be sure it's seated would be a good idea.

If you put all the parameters back in and get the ROM parity alarm again, see if it gives you any numbers. Usually the system 6 displays the address of the offending EPROM chips.

[starn36]

Thanks

I red my parameters successfully.

So, I still have the 210 alarm (X+ OT). It's concerning the limit swith. I tried to use the "overtravel release" button, no move.

What I must to do. Maybe turn manually the drive axis.

Thanks for your response

[Dan Fritz]

Press the DIAGNOS key and look at diagnostic #032. You should see a "1" in the bit on the far right (bit 0). That's the input for the +X limit switch. The bit right next to it (bit 1) is the -X limit switch. The Z axis limit switches are the two right-most bits of diagnostic #033.

If diagnostic 032 bit 0 is a "0", that means that you don't have a +24v signal on the limit switch input, which is on connector C02, pin 45. Your axis limit switches are all "normally closed" switches, which means that +24v is passed through closed contacts of the switch normally. When the slide hits the switch, the circuit is broken, and +24v is removed from connector C02 pin 45. This puts the control into +X overtravel and only lets you jog away from the limit switch.

Check for a stuck switch and also for a broken connection in the cable to the switch. Lots of OT switches fill up with oil or coolant, and sometimes one of the wires will break inside a flexible cable duct. If you can wiggle something and make the diagnostic bit become a "1", then you've found your problem.

[starn36]

I moved the machine with jog button and overtravel button. The limit switch seems to be good when I check the diagnostic.

However, the machine is still NOT READY. I cannot ligth on the yellow button (STANDY-BY). This was working until I erase the parameter. I have no alarm excepting the 998 rom error that pop after a while.

Concerning the rom error, I pressed on each chip to be sure.

Do you have other way to resolve my problem of startup first.

[Dan Fritz]

Now you're describing a different problem. The 210 +X OT alarm is the signal I described, but you apparently don't have that problem anymore (??) The NOT READY is because your control is in E-Stop. You probably have a SECOND set of overtravel switches that are wired into the E-stop circuit.

On a typical machine, you will have THREE switches that are actuated in the + direction. One is the zero-return decelleration switch, the second one is the + overtravel switch, and the third is the "extreme" overtravel switch that puts the control into E-stop. That last switch is intended to stop the servo if it should "runaway" with a serious malfunction. Normally, all the extreme OT switches are wired in a series circuit so that any one of them will break the circuit and put the control into E-stop (just like pushing the E-stop button). Look at diagnostic #038, bit # 4 (the 5th bit from the right) for E-stop. It must be a "1" to get rid of the NOT READY condition and permit the servos to run. That signal is on connector C02, pin #3. If you press the E-stop button, or hit any of the extreme OT switches, it will set that bit to "0" and hold the control in E-stop.

Both the +X overtravel and the +X extreme OT signals will be routed through the same flexible cable duct. Are you sure you don't have a broken cable?

[starn36]

Yeah

I'm ready! i found the X limit switch and one of the pegs (the extreme X+) was jammed on down position.

So, I return to my real problem, the ROM error. First, can I do a memory test.
I tried to do "-" & "." & "power on" but I'm not able to choose one of the options. I press "6" with any combinaison but nothing happends.

Can you help me for this diagnostic.

[Dan Fritz]

When the control displays the 998 ROM parity error, it should also have a couple of other numbers on the screen that tell you WHICH ROM chip is defective.

Look for the ROM board (plugged into the main board). It should be plugged into the connector marked "CAB" on the main board. On this board, you will find a bunch of EPROM chips, which contain all the controls executive (firmware). Be sure that all these EPROMs are seated completely in their sockets, and look for pins that are "bent under" the chip. A magnifying glass is needed for this. You can remove the ROM board and put it on a bench without worrying about battery backups, etc. Just put it on a clean, soft surface.

If there is a number on the screen with the 998 alarm, it's probably the ROM chip location on that board that's got the problem.

[starn36]

Thank you for your response

Unfortunately, I check all the chips (more attention on the "102"). I put the chip out and I replaced it. Nothing's good.

Can I try to interchange two chips?

Do you have other ways to investigate this problem?

[Dan Fritz]

The EPROM chips are not interchangeable. They each have a unique segment of the executive program burned into them. If there is nothing obviously wrong with the "102" EPROM, and you're getting the number "102" on the alarm 998 display, then you probably have a bad EPROM chip. You will have to replace it, or perhaps replace the entire set of EPROMs.

You say that you "replaced it". Did you replace it with a new (blank) EPROM chip? If so then you should put the original chip back in it's place. A blank chip would generate the 998 alarm for sure.