0M-C Fanuc 4th Axis Retrofit - Not decelerating on reference return

[HardyHarr]

Hoping to pick the brains of a few local gurus here.

Problem:
Rotary table does not decel when I try to home it. It will just spin endlessly until I hit reset... UNLESS: If I boot the machine with the rotary close to home (or rather just before it) (IE. when the Normally Closed decel switch is triggered and “open”, thus not providing 24vdc to the M20-25 (DEC4) connector on the I/O C7 card) then it moves at decel speed and homes perfectly with the little “0” mark in the table t-slot facing perfectly upright in the 12oclock position. HOWEVER! If I boot up the machine with the rotary table nowhere near home position (IE. when the NC decel switch is closed, thus giving 24vdc to M20-25) then the rotary will just spin endlessly at rapid speed during ref return, the decel signal is not registered when the dog trips the switch and removes 24v from M20-25 (DEC4).

If I go to the diagnostics page, the M20-25 (DEC4) pin corresponds to X019.5, if that’s a 1 then it means M20-25 has 24v on it and the machine should be in rapid mode right? (I know there's a parameter that changes this, but mine is set as default) The problem is that once this pin has 24v on it, as soon as you take that 24V OFF (when the rotary table decel switch opens) X019.5 does NOT change back to 0 to enter decel mode... It stays as a 1… so that’s the reason it’s not decelerating as far as I know, but why does it not change back? I checked voltage on M20-25 (DEC4) when 24vdc is removed and it has 10.4vdc on its own which does not seem right at all, could that be why it stays on??? The Z axis for example (M1-40, DECZ) only shows 0.4vdc when the Z-axis decel switch is open and 24vdc is removed. Could a parameter somewhere be causing this mysterious 10v or is it more likely a hardware issue? Or is it a non issue and a matter of a completely different parameter/hardware issue? I removed the I/O card and inspected it, I can see no signs of burned out components or short circuits.

All the other other axes work properly, when you press the decel switch, the circuits opens, 24vdc flow stops, and the corresponding diagnostic bit (DECZ X018.5, DECY X017.5, DECX X016.5) changes from 1 to 0... and back to 1 when you release the NC switch.. But not the 4th axis. If you boot the machine without the 24v connected to M20-25 (DEC4) all of the X019 bits initialize as 00000000, and the rotary will be in decel mode, but as soon as it has 24v it goes to 10101100 and stays like that with or without 24vdc. The other thing that stands out to me is X019.2(+4) and X019.3 (-4) are both 1’s, Not sure if this could be related, I have no idea if these are inputs or outputs or what they are, X and Z both have only bit#2 as 1.. and Y seems to be both 0’s.

Background Info:
Its a 2000 Feeler FV-800 Mill and I’ve added a 1996ish Tsudakoma RCNX-251 rotary table that I purchased off ebay. The rotary is a 90:1 gear ratio and has an Alpha C6/2000 servo motor with an I64 pulse coder (A06B-0126-B077). The machine is equipped with a 0M-C computer (A02B-0098-B511), 1-4 Axes Card (A16B2200-0390/11B), and an I/O C7 (A16B-2203-0110/03A).

I’ve added an SVM1-40L servo amp (A06B-6079-H104) to drive the 4th axis, it’s all hooked up, I followed the Fanuc Series 0 Servo Amplifier manual to set the servo parameters. I’ve enabled some 900 series option parameters to turn the 4th axis on and the 4th axis ref return function, as well as some MTB parameters that are documented in my Feeler machine manuals related to the solenoid clamping/unclamping. The rotary spins, sounds decent, the servo motor sounds smooth, the table clamps and un-clamps automatically when i press the jog buttons, no alarms or errors on the control. I feel like I’m the only one who always encounters the strangest problems lol, maybe because I take on strange projects. Any ideas appreciated.

X019 all zeros at startup without 24v:


X019 after 24v is applied AND removed:


Diagnostic Bits:


My Parameters are attached as well, maybe I have goofed something up.

Brad



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[the_gentlegiant]

From what I know, it seems you have done everything correctly except sizing the amp. (See below) That residual voltage is saying partial short or faulty decel switch activation, or coolant in the switch. Un-hook the decel switch cable and measure with an Ohm meter. Measure on the cable end or open the switch access cover and measure there with at least one wire disconnected to isolate the switch, or leave connected to verify the cable/switch as a whole. That will tell you if you have physical problems with the switch and/or cabling. You might also verify that the rotary is moving in the correct direction so the decel dog is being tripped with the proper timing. I installed a Tsudakoma 301 on a YCM with Fanuc O, and I'm guessing it's similar. With the table mounted vertically on the right and facing in the minus X direction, it should rotate clockwise or towards you when zero returning with a +A button push. (If that's how your machine operates.) There is a parameter that changes this direction if need be.

FYI - Technically you're not running the correct amplifier for that servo motor. Your amp is for a a6/2000 not an aC6/2000 which asks for a SVM1-20. (A06B-6079-H102) Not sure if over-sizing is a problem or not. And I doubt it has anything to do with what's going on here with your home positioning.

One last question- why are all your X10 and X12 inputs going high form one screen to the other? According to your pdf, they look like empty function inputs. Although the MTB could have filled them up with something. Still odd they're all going high. Just curious what that's about.

[HardyHarr]

At the time I bought the amp I did some searching and I recall reading a thread where someone said a larger amp should theoretically work? I guess I have proved that? Although maybe not perfectly.. after all the axis's are homed, the 4th spins way too fast at 100% rapid and alarms out quickly, giving me a 349 SPC Alarm: 4 Axis Pulse Coder. If I turn down the Rapid speed in the parameters, the servo motor started kind of low frequency vibrating. If I turn it to 25% rapid its good, and the servo diagnostic page says the servo motor is spinning at about 1800rpm. I guess I will have to learn how to tune this mis-matched setup?


Also I have made a mistake in my explanation in the first post, the 4th axis is not homing when I boot the machine with an open decel circuit, it will just spin endlessly at decel speed, but the 4th axis DOES home anywhere during rotation when 24v is applied to the decel switch (I unhooked the decel switch and attached a toggle switch for testing purposes), it just stops cold anywhere I flip the switch and it turns the display to A0, and the A0 home LED on the panel lights up, like the 24v applied to the DEC4 input is also giving it the 4th home signal. I have triple checked the wiring, there are no shorts in the decel circuit, and i have ruled out a faulty decel switch since I put a toggle in place of it. The rotary is moving in a clockwise direction when facing it, and I can confirm that my Tsudakoma manual says this is the standard ref return direction.


I have no idea why those bits are 1's. The feeler books I have say the bits in X010 and X012 are for pallet changer functions (which I dont have), all the inputs for the pallet changer are on the M20 connector of the I/O-C7 card, I don't have anything hooked up to those corresponding pallet changer pins, the only wire I have connected on M20 is the the 4th Axis decel input.. pin 25. H4,+4,-4 are also on M20, do I need to apply 24v to any of those? (Mind you they all read 18v on their own with only the DEC4 input connected)


Other things I could note, after I home the 4th with the toggle switch, and home all the other axes, the 4th will rotate fine in rapid by pressing the rapid keys (so long as im on 25%) and it will move in handle jog in all three increments .0001, .001, .01, but it does not work in MDI, typing G0A90. or G1A90.F20. for example, the control basically ignores it and nothing happens, I haven't tried a program in memory yet though. Also when I boot the machine, the A position always reads 0, its not saving the position at power off.


I thought I had an idea how to make this all work when I started, now I have basically have no clue.

[zavateandu]

it happend twice in my life and i use to insert a small resistance or a led on the way to discharge that voltage down after 24v is off.
hope it helps.

[the_gentlegiant]

Hi Hardyharr,

Okay, I guess you've got a way to go after all. To start, according to your attached parameter file, you have many of your servo motor parameters set incorrectly. I've attached a corrected file. Still, keep your backup. I can see you're running a6/2000's on your X and Y axis and an a12/2000 on you Z. Where did you get the parameters for your 4th axis? If they were already on the control, it could be that the previous owner had a completely different motor installed. Note that I think when you enter in the motor type no. 8, the control fills in a bunch of the rest. Can't remember. Also, and I always have trouble with this, according to my param book you can try a AMR of 00000000 and a CMR of 2.

I don't think you completely understand the decel homing thing. To home the axis, the trip dog has to contact the switch, and then when it falls off the switch, that's when the grid starts counting. Meaning it's a on/off (or potentially off/on) thing it's looking for before it starts counting. You adjust your grid shift parameter amount to get the thing to home dead on. If you have trouble making that happen, sometimes you have to move the physical trip dog a little and try again. Also because of the incremental encoder, the jumper on your drive should be on S1, not S2. (likely already is) Also your encoder cable should go to the CNC first, then from the CNC to the JV1B connector on the servo drive.

Usually I'd say stick to the MTB manuals, but here it wouldn't hurt to get all the manuals for the Fanuc OMC control, the Alpha series servo motors and amps, both connection and function. Parameter book and the lot. There is a bunch of information and parameters beyond the motor ones that need to be set if I remember correctly. Also if you're having minor stability problems, there are settings that aren't part of the normal ones that you can adjust to get rid of odd problems.

During my install, I spent hours pouring over the books and getting everything to go, but in the end I called in a local tech to go thru everything and finish the setup. Sometimes it just pays to pay and get it over with.

One last thing, and maybe you already know this, but to turn on and off the 4th, all you have to do is change parameter 19.1 to 0 to enable and 1 to disable. Can leave everything else as is.

[bill4807]

Hi Hardyharr,

Okay, I guess you've got a way to go after all. To start, according to your attached parameter file, you have many of your servo motor parameters set incorrectly. I've attached a corrected file. Still, keep your backup. I can see you're running a6/2000's on your X and Y axis and an a12/2000 on you Z. Where did you get the parameters for your 4th axis? If they were already on the control, it could be that the previous owner had a completely different motor installed. Note that I think when you enter in the motor type no. 8, the control fills in a bunch of the rest. Can't remember. Also, and I always have trouble with this, according to my param book you can try a AMR of 00000000 and a CMR of 2.

I don't think you completely understand the decel homing thing. To home the axis, the trip dog has to contact the switch, and then when it falls off the switch, that's when the grid starts counting. Meaning it's a on/off (or potentially off/on) thing it's looking for before it starts counting. You adjust your grid shift parameter amount to get the thing to home dead on. If you have trouble making that happen, sometimes you have to move the physical trip dog a little and try again. Also because of the incremental encoder, the jumper on your drive should be on S1, not S2. (likely already is) Also your encoder cable should go to the CNC first, then from the CNC to the JV1B connector on the servo drive.

Usually I'd say stick to the MTB manuals, but here it wouldn't hurt to get all the manuals for the Fanuc OMC control, the Alpha series servo motors and amps, both connection and function. Parameter book and the lot. There is a bunch of information and parameters beyond the motor ones that need to be set if I remember correctly. Also if you're having minor stability problems, there are settings that aren't part of the normal ones that you can adjust to get rid of odd problems.

During my install, I spent hours pouring over the books and getting everything to go, but in the end I called in a local tech to go thru everything and finish the setup. Sometimes it just pays to pay and get it over with.

One last thing, and maybe you already know this, but to turn on and off the 4th, all you have to do is change parameter 19.1 to 0 to enable and 1 to disable. Can leave everything else as is.

Those bits that are all going high..from what you say is the m20 connector, and you only have one input that's true?
This may be do to a floating common on that input card. This happens depending on the fanuc I /O module used, if you miss the 0vdc connection one input could trigger them all high.

[the_gentlegiant]

Something I forgot to mention about the parameter file supplied earlier. It is for a aC6 Servo used on a 4TH AXIS ONLY. The number after the "8" designates which axis. You want to use it on another axis you have to change the number after the 8 (which in the supplied file is "4") to the axis you're working on. X=1 Y=2 Z=3