Re: EMC stg2mod.o and problem with homing

thanks Less for such a detailed reply! I am using SERVO TO GO MODEL
II 8 AXIS card.
Please tell me if i can do the same kind of hack as paul did? i mean
writing directly 1 to IDLEN and 0 to SELDI somewhere in newstgmod??

regards
Asim

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Leslie M. Watts"
<leswatts@a...> wrote:

> Hi Asim and Jon
>
> It is beginning to look like the index latching bug.
>
> To explain:
>
> With your version and some others homing would not work
> with ANY of those modules (including newstgmod.o) with the
> Servo to go II 8 axis card. Only newstgmod worked with the
> Servo to go II 4 axis card.
>
> Asim, I still need to know if you SPECIFICALLY have the
> SERVO TO GO MODEL II 8 AXIS card to be able to help you.
>
> When Paul Corner was visiting last year I hunted up the address
> of the STG registers IDLEN (0x409 offset) and SELDI (0x40b offset)
> that respectively enables index operation and uses the encoder

rather

> than an external signal.
>
> Paul did a hack by directly writing a 1 to IDLEN and 0 to SELDI
> somewhere in newstgmod. I still use this on my machine, but Paul did
> a little more structured fix on later versions I think.
> I need to get to Paul about this so you can get the right version.
> Are you on the emc list?
>
> As for the ini variables...
>
> HOME_SWITCH_POLARITY depends on the logic of the switch... I use
> normally closed switches and set it to 1.
>
> HOMING_POLARITY is the DIRECTION the axis travels to seek the
> home switch. 1 is positive direction, 0 is negative. It can be

either way,

> but I have the home switch at minimum count, so I use a value
> of 0.
>
> So here is a typical sequence:
>
> command home
>
> axis moves in the negative direction (HOMING_POLARITY=0)
>
> when limit switch is opened by the axis motion direction
> reverses, speed doubles. This is due to (if I am remembering right)
> JOGGING_POLARITY=1 (the positive direction). The speed doubling is

hard

> coded.
>
> The first index pulse detected
> will be defined as home. It will stop there and axis numbers
> will zero and turn green.
>
> In my case the motion continues past this to the axis center
> of travel because I have a non-zero HOME_OFFSET. In that case
> the axis travels to the HOME_OFFSET value, zeros, and goes green.
>
> Many other homing sequences can be done by alterations of these
> parameters.
>
> An example of a known to work ini file using stg II 8 axis and
> normally closed switches is on my engineering website
> below. Follow the cnc links.
>
> Les
>
>
>
> Leslie M.Watts
> L M Watts Furniture
> Tiger Georgia USA
> (706) 212-0242
> http://www.lmwatts.com
> Engineering page:
> http://www.lmwatts.com/shop.html
> CNC surplus for sale:
> http://www.lmwatts.com/forsale.html
> CNC carved signs:
> http://www.lmwatts.com/signwp.html
>
>
>
>
> -----Original Message-----
> From: Jon Elson [mailto:elson@p...]
> Sent: Monday, September 22, 2003 2:08 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: EMC stg2mod.o and problem with

homing

>
>
>
>
> Asim Khan wrote:
>
> >Hi Les, Jon and the group!
> >I was on holidays so i coundnt experiment with the HOMING_POLARITY
> >I changed the HOMING_POLARITY to 0 and 1 but it has no effect!
> >i also changed the motion control modules, i had experimented with
> >newstgmod.o stgmod.o, stg2mod.o and stg8mod.o but each had same

result

> >that is, the axis donot home! donot turn green.
> >I'had setup EMC on two machines,
> >My machine's encoders support index pulse outputs.
> >the encoder resolution at one machine with servo2go card has
> >800 CPR and the otrher machine has 2500 CPR resolution. but both of
> >machines are unable to home.
> >please suggest where this trouble lies and what might be solution

to

> >this problem? are there any working systems with Servotogo cards on
> >EMC? and those have no homing problems?
> >
> >
> OOps, I think you have to change the sign of HOMING_VEL!
> Actually, I don't know what the difference between HOMING_VEL
> and HOMING_POLARITY is? Maybe HOMING_POLARITY
> is the polarity of the index signal from the encoder! I think it

is, so

> my original info was wrong (But, I was within 4 lines of the

problem!)

>
> I know this worked on exactly the same situation at my client's.
>
> Jon
>
>
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