Absolut encoder with a Mitsubishi

I have to renew a machine witch 4 absolute encoders.
It has to be absolute encoders but I am not sure what interface it should be. (Parralel, SSI og Profibus).
And what code should I operate with? (Gray code or Bin).
The machine is for pollishing washbasin. It has 4 "arms" and each arm is pollishing a washbassin. The problem is that if it comes near a corner the "arm" can jump backwards ~5°. How does the encoder handle that? Let say the arm is reatching 280° and the "arm" jumps back 5°.
Would my signal in the mitsu be 280° or 280°+/-5°?
The other thing is what Mitsu PLC can I use? My lokal mitsusupport has told me that I have to use either Parralel or a bus-system (Profibus). I can not use a encoder with a SSI-interface, because it vil give me a lot of programming trouble, can this realy be true?

Dariusch

Parrallel encoders (most come with gray ) are very simple to use.
The only downside is more conductors which is not always practical.
Mitsubishi PLCs come with instruction to convert gray to binary
(you always need binary) although conversion is very simple even
wothout it. I imagine that polishing arms are not moving very
fast so jump of ca 5deg should be no problem to detect - in either direction.

Thank you Panic mode for your fast repley. But I still have som questions that I hope you can help me with.

1)Do you think that I should use encoder with Parrallel-interface
instead of the other options?

2)I have looked at the FX-programming manual, and is it only the FX2N
that has the Gary-code instrustion? Can't I use a FX1N without the
gray-code inst. and if how do I convert the signals?

3)If the "Arm" jumps 5° how do I se that in the PLC, I figure that if
I convert the gray-code in the PLC I would get a 0-360° signal, so
if the "arm" jumps 5° backwords would the be, for eksample 275°
instead of the real pos. that is 280°??

Thank you

Dariusch Shirzad

check this link for details. It will work on any plc, i was applying it on
mitsubishi as well - until I've found that there is instruction
for it

Converted value is just a binary number with number of bits matching
number of signals wired to the PLC (you don't have to wire them
all if you don't need full resolution).
Then you have to scale this number to engineering units.
(simple division or multiplication will do).

Thank you Panic mode for the example, that will do.