Fanuc PS/90 Alarm

[mattstawicki]

I have a Tornos ENC-74, with a Fanuc 0tt control. I turned it on tonight to start a new set-up, and I'm getting a PS/90 alarm during zero return (head 1, X-axis). I've tried resetting the cooridinate system (G,P,& Can) - no help. The proximity switch appears to be working and the control is getting the signal (dgn 0.0 changes from 0 to 1 when switch lights). This happened about 3 months ago, and I turned it off and on again about 4 times and it cleared. It won't clear tonight.

Anybody have any thoughts/solutions?

Matt

[bborb]

My manual says:
The reference position return cannot be performed normally because
the reference position return start point is too close to the reference
position or the speed is too slow. Separate the start point far enough
from the reference position, or specify a sufficiently fast speed for
reference position return.
Does this apply?

[bborb]

I'm guessing it means to jog farther away from "home" before zero return and don't have overrides set low.

[mattstawicki]

Haven't been able to play with it for a few days (or look at this site). Jogging the axis to a different position was one of the first things I tried. That didn't help. Even tried to change the X-axis grid shift parameter, still didn't work. Tried to trip the switch manually (in a number of different positions), and that didn't work either. Have also disconnected/re-connected the axis board and all the cables (thinking that perhaps there was a bad connection - I've seen this help with other problems), and it didn't help. I'm beginning to think I've got an end-coder problem.

Matt

[bborb]

Do you have "absolute" encoders? When you powerup, does the position page show you're at 0,0,0 or some other position?

[mattstawicki]

bborb,

All zero's, all 4 axis'.

A brief explanation.....
I forgot about it when I started this thread, but I blew an X1-axis belt about a year ago. I never re-calibrated the x-axis. I remember why now, I couldn't find the procedure I had for finding end-coder zero, and setting the grid shift (tried to find it yesterday). I used to work for Tornos, and know a few tricks that I used at the time to get it running.

I rarely turn this machine off. Have an automatic bar loader on it, and run it 24/7 most of the time. As long as you're not trying to hold better than +/-.0002, you really only need to stop in once in a while to empty the parts pan.

This machine only searches for zero when referencing after the initial power on. After that, as long as power remains on, it never looks for end-coder zero, or at the proximity switch. Machine reference (zero return) is handled automatically. All 4 (5, including the sub-spindle), zero out, and set themselves at the machine coordinates.

This PS/90 alarm surfaced for the first time about 6 months ago when we had a power outage. I re-started the machine a few time, and it went away. Haven't shut the power off since. Until, that is, last week when it was so hot out here (San Diego area). It have just finished running a 40k piece order sometime during the night on Friday. I wasn't going to set up the next job till this past Monday, and it was so damn hot, that I though I'd give it a break for the weekend, so I shut it off Saturday morning.

This past Monday is when the trouble started. I haven't had much time to play with *my* machine, because I've been rather involved in helping a guy who's moving his shop down here from up North. I still do a lot of service work on the older Tornos CNC & cam machines. So far I've installed 32 cam machines, and just finished installing another 18 CNC's.

The funny thing is, he has a machine just like mine....that had the same problem! I was able to clear his alarm by messing with the grid shift. Changing the grid shift parameter didn't work on mine. That's why I was beginning to think I had a servo end-coder problem (dirty scale maybe?).

I was messing around with it this morning and finally got it running. What I did was change it from inch to metric. On the Tornos, you don't simply change the inch/metric parameter. They have a macro that changes all the machine coordinates, and a few parameters. I ran the macro on both channel 1&2 (head 1&2), and it actually referenced!! No more PS/90 alarm!!
Changed it back to inch, and it's still OK (didn't need to be referenced again).

You can be sure that thing won't see power off again for a while.

Now, that doesn't mean that the axis doesn't need re-calibrating, but at least it's running for now. I've contacted a friend who still works for Tornos who'll send me a copy of the procedure, and when I get a little time, it *will* get re-calibrated.

Guess that explanation wasn't so brief:-)

Matt

[rgdmachine]

Hi guys

we have the same problem with our Chevalier VMC 2033 , with FANUC OMD , when i send the X and Y axis to their Zeros the sistem shows an 090 P/S ALARM , please i need your help we cant to work !!!!

I hope your comments.

[323ci]

Well I ran into this problem when our servo motor windings became wet from coolant and had to remove it to get it baked, there was a hole from corrosion in the aluminum case.
The issue with our chucker, a J&L TNC 1508 Fanuc OT has p/s 90 alarm when homing the x-axis.
The cure for this was to:
Power off the disconnect. Remove the servo-motor, rotate the shaft 180 deg. Power up disconnect, turn on control. Home x axis…. Over travel occurred in mid travel. Turn off control and power up holding P, CAN buttons. Home the x-axis.

I did not want to change the homing switch ramp, which may have done the same thing, my thought was this way the part programs would not have to be changed.
Now everything is as it was.