Mirac PC homing in the wrong direction on the X axis

bradders · Post by **bradders** » Wed 24 Jan , 2007 9:54 am

My Mirac PC (DOS 1.47 1999) is homing in the wrong direction on the X axis, I have swapped over one of the motor wire pairs and now it homes in the correct direction but jogs in the wrong directions, any ideas? i am using a Desktop Tutor

Post by **Denford Admin** » Wed 24 Jan , 2007 10:51 am

Whats the history of the machine ?

If it worked OK before, then you shouldn't have to swap the motor phases.
Its more likely that there is a fault with the home limit switch - especially if the axis now jogs the wrong direction.

bradders · Post by **bradders** » Wed 24 Jan , 2007 11:08 am

It was initially Homing in the wrong direction

A bit more history.....
1) We are using DOS software.

2) We have checked the 4 core wiring continuity of the X axis sensor.
Everything is OK, I mean, it is not damaged.
Procedure performed: We turned the machine on and HOMED the Z axis. When the
table reached the switch (0z), the PC reseted the Z axis position for 000.
When we HOMED the X axis, it moved away to the opposite side.
However if you short-circuit the terminals of the X switch, the table stops
and does reference with 000. The axis come back moving away properly using
the JOG function with the KEY TUTOR.

3) We have swaped the x axis drive card over with the y axis card and the
problem stays with the axis.

4) The speed of the x axis is correct, I mean, it is moving away properly.

5) I suppose that the EPROM can be damaged. Could Denford provide another EPROM for DOS software ?

It looks as though the problem is the homing direction ONLY is wrong, but everything else past that is fine

davidimurray · Post by **davidimurray** » Wed 24 Jan , 2007 15:52 pm

Sounds like a knackered home switch. It should work in one of 2 ways :-

1 ) It should work by having a normally open (NO) contact, when the switch is open it homes in one direction. When the switch is closed the direction of travel is reversed until the switch goes open

2) It should work by having a normally closed (NC) contact, when the switch is closed it homes in one direction. When the switch is open the direction of travel is reversed until the switch goes closed

Probably the easiest way to test is to try removing the connections from the limit switch and test the homing switch action using a continuity test. You coud also home the machine without the limit switch connected and see which way it homes. Then touch the two wires together and see if the homing direction changes. If it does then the switch is at fault.

Cheers

Dave

bradders · Post by **bradders** » Wed 24 Jan , 2007 16:01 pm

Cheers for that Dave, I think i got the customer to check the datum switch last year. I have forwarded the link to him so i will see what the outcome is.

Mr Magoo · Post by **Mr Magoo** » Wed 24 Jan , 2007 20:45 pm

Are you running the right software? Using the wrong software for the machine could give these symptoms !

Is the machine runing MIRAC or FLSTEP software?

I've taken a quick look at the FLSTEP code and their isn't an option to change the homing direction of a single axis (only a global setting that changes all axis...
SLAVE_DATUMTYPE
0 = one direction
2 = other direction

I can't find any settings in the MIRAC software that may do this.

bradders · Post by **bradders** » Thu 25 Jan , 2007 8:38 am

Cheers Jim

Post by **Denford Admin** » Thu 25 Jan , 2007 12:29 pm

We seem to be at a loss as to whats going wrong...

MrMagoo - was there ever anything in the code to do with front or back turning ? That would effect homing direction ?

(btw Dave says it must be FLSTEP as Mirac was for the GSM boards)

Customer - Can you tell us what happened to cause this ?
Did the machine suddenly start homing the wrong way ?
Was the machine moved or reinstalled ?
Have any connectors been disconnected and replaced ?
Has the power source changed ?

Has the home sensor been replaced ? It will be a proximety switch thats either NPN or PNP
Can you double check the connections and operation of the home sensor ?

Mr Magoo · Post by **Mr Magoo** » Thu 25 Jan , 2007 13:00 pm

I can't see any options for Front / Back turning in FLSTEP! (I don't think FLSTEP ever supported this feature)

Can you also define the symptoms of

homes in the correct direction but jogs in the wrong directions

When you jog with the "X+" jog key on the Desk Top Tutor I want to know...

1) Does the tool move away from the centre line?

2) Does the X Axis display increase or decrease in value?

(ie could it be that the jog push buttons are the wrong way round?)

Denford Software & Machines

Denford Software & Machines

Mirac PC homing in the wrong direction on the X axis

Mirac PC homing in the wrong direction on the X axis