GEFanuc S-400 Robot Trig Problem

Alright guys, I've stumped not only myself but quite a few others. I'm dealing with an S-400 robot made by GEFanuc that I need to have the ability to calculate ArcSine and ArcCosine which are incidentally not built in functions (am using KAREL 1.5 for the programming language). I tried to compute the infinite series that approximates these functions but to no avail due to an integer overflow. So, my last hope (unless one of you is aware of how to compute the infinite series inside the robot) is to use the RS-232 connection to take the 4 values entered by the operator and take them out to a PC, compute the values that I need, and then send them back to the robot to be placed into variables.

My only problem is, I haven't the foggiest idea of how to set up the RS-232 communications to and from the robot, nor am I sure how to get the robot to read the values into the appropriate registers (as RS-232 is asynchronous, isn't it?). If anyone can help on this I would be most appreciative, because I'm at my wits end with how to compute the Arc Trig functions that I need to make this program work properly.

[Stevo]

I might be no use to you as I know nothing about the S-400 Robot. I however work a lot with the Fanuc controls.

Are you saying that you are getting an overflow alarm when trying to run this due to the fact the calculation has more integer's then it is allowed to read? All of my Fanucs have the ability to do ACOS and ASIN. It also has the ability of ROUNDING function. Can you round this number to the integer that you desire?

I apoligize if this doesn't help. Just throwing it out there.
Stevo

Hey Stevo, I appreciate the prompt response regardless. The controller doesn't have any external markings as to which controller series it is, however, I know it was made in 1986, so it just doesn't have the ASIN and ACOS functions in it at all. Mind you, this is a robotics controller, not a classic CNC controller, but the application is an end milling process on a part that varies in size.

The infinite series for the functions are found here:
http://en.wikipedia.org/wiki/Inverse...nfinite_series

And the problem is that the factorials grow to an enormous size in just a dozen N values, and I need N = 20 to get the kind of resolution on the angles that I need. The angles have to be real values as well because the difference between 6 and 7 degrees on my tool facing can create a visually noticeable problem with the part.

So, that being said, I need to have a way to get at these values, and the only thing I can think of is using an external computer to compute them, but the communications portion of it eludes me. If there is a good way to make these series operate though, I'd be happy to give that a shot.

Ryan

[Petro]

I found this on http://www.robotica.fr/telecharger/f...20Ver.6.31.pdf
Not a programmer but looks like might help. I found below on page 7-21 of the above manual. I searched for deimal in PDF.

Text (ASCII) Output Format Specifiers
DATA TYPE 1ST FORMAT SPECIFIER 2ND FORMAT SPECIFIER
INTEGER Total number of characters written Number base in range 2-16
REAL Total number of characters written Number of digits to the right of decimal
point to be written
If negative, uses scientific notation
BOOLEAN Total number of characters written 0 - Left justified
1 - Right justified
STRING Total number of characters written 0 - Left justified
1 - Right justified
2 - Left justified in quotes (leading
blank)
3 - Right justified n quotes (leading
blank)
7–

Well, as I was looking up system variables for a completely separate problem, I came across a reference to inverse trig functions in the table of contents under "Additional Mathematics Equations". This uses ATAN2 to calculate the inverse trig functions in a fairly straightforward fashion. Just in case it comes up, I'll post the solutions here just in case someone searches for it...someday, somewhere.

None of the 4 or 5 techs from Fanuc or the firm we bought the robot from could provide me with this answer and it was only by shear luck that I found it...gotta love 20 year old technology.

[thomoky9]

I created a similar machine and I used an AE-MDL-DualusDC chip. The chip allows you to get 1A RMS, 2A peak, per H Bridge and its really small. Both sides of the chip allow you to control the power and control signals. If you need to solder your own wires on it has SMT pads as well. I found some really cheap ones at DriverDudes.com, you can get just the board or have it fully assembled.