Adding 4th/Rotary Axis to XYYZ CNC Router. A or C Axis ?

Ohh this is possible. I will check that when i am back in the workshop on tomorrow, but thank you very much for your quick reply. At least i now know that its not normal. I will check the connection on tomorrow and then i will update.
Thanks!

Its working, you were right. Thank you! 

Just one question, because i am a bit confused.

When i touch off my A axis it shows 0.000 on the DRO. When i then run the program, the A-axis rotates to the first position e.g. A-0.485, and it seems that everything is alright while dry-machining, but at the end of the program the machine goes to A0 (as it is in the code), but the A0 position is the physical position of A-0.485 .
So, the position from the touch off before running the g-code is after finishing program not anymore the same.
The "new" A0 is the first position where the A-axis rotates to, so A-0.485.
I need to check if its physically really at A-0.485, but i have run the program 3 times and always it was at the same position after the program has been finished.
Its like the program or the post processor creates a new 0.000 position, but when i restart the same program it does not anymore rotate to A-0.485, because it is already o that position. Strange for me.
(i can post the g-code on tomorrow, because i cannot find the usb stick right now)

I have tried to recreate the g code on my pc at home and i believe its about the same, so maybe someone will find out why such behavior.
*i am currently lerning what all those G codes mean, as for example G54, etc.

Now i am getting it. I have learned something, thank you.
I feel a bit bad, because i have build a couple of CNC machines, but i am almost unable to write a simple g-code. I have to spend a bit of time working with g-codes.
Have a nice weekend:)