828D communication with a rotary indexer

Hello,

I am looking for some help fitting an electronic indexer to one of our machines, the indexer is an actual 4^th axis which we did intend to use as such, but unfortunately, as far as I am aware, the indexer does not have Siemens motors and I have been told it will not work as a 4^th axis on the Siemens controlled machine due to this.

The Unit came with its own software/controller that allows it to be programmed as an indexer, which we have been using on another machine, what I would like to do is fit this to the Siemens controlled machine and use it as an automatic indexer, to do this though I need to get the machine to communicate with the control to tell it to index around when the program is ready, an I/O signal (imput/output)? Could anybody advise me on what I need to do to the machine to get a communication between the two? I will still be using the Alpha control that the unit came with to do the indexing, the machine will just tell it when to pulse. I have all the wiring in place to connect the unit.

The machine is an XYZ 710 VMC running Siemens Shopmill 828D (http://www.xyzmachinetools.com/index.cfm/machinetools/Products.Details/product_id/330/subject/xyz_710_vmc )

The indexer is a Nikken CNC 180 ( http://www.nikken-world.com/en/rotary-table/CNC180/4 )

Thank you kindly in advance for any help that can be offered.