I have some IAI linear actuators type ISDL, that I want to make an 800x600 xy table. These actuators have 200V 400W 8 pole 3000rpm AC servo motors integrated directly onto the ball screw spindle. I would like to retain them if at all possible, but suitable IAI controllers are almost impossible to get hold of. Shaft rotary position is resolved to 17 bits by a Tamagawa absolute (1 revolution) encoder. Position data is transmitted serially at 2.5Mbaud by a two wire differential pair.

I can get a hold of some Yaskawa SGDM-04ADA-V AC servo drives at a quite reasonable price, and the voltage and power levels match. The drawback with these is that they communicate directly with the motor encoder electronics on startup for motor type data, and the drive will give a fault if the attached motor does not return a valid Yaskawa motor code.

To make it all work I figured that I could knock up an AVR or PIC interface to act as an interpreter between the Yaskawa SGDM and the IAI encoder. This would convert the serial position data to the appropriate format for the Yaskawa drive and also respond properly with the appropriate motor data when interogated at start up.

I've looked in all of the Yaskawa literature that I can find on line and cannot find any of the technical details of this electronic intercourse between the Ysakawa drives and the Yaskawa motors. So I am a bit stumped there before I start.

Secondly, I can find no data on the rotor alignment at the encoder zero point. This is critical for AC servo drives as it is the very cornerstone of proper phase synchronisation and actual rotor position.

So I have two questions for the learned gentlemen of the forum

1 - Does anybody have access to the technical details of the yaskawa SGDM-04ADA-V encoder interface and the automatic motor identification process that is performed on start-up?

2 - Am I dreaming the impossible dream? Is it just too darn difficult to mix and match AC servo drives and motors from different manufacturers? I am seriously tempted to take an axe to the existing integrated AC servo motor and replacing with an external step or brushed servo motor. These actuators are so beautiffuly made and dust tight, that I would hate to tamper with their envelope integrity. Is there a better way that I haven't thought off?

This is my first serious post. Feel free to tell me if I've posted this in the wong place, broken some ettiquite (I'm not even sure if I can spell the word), or just plain rambled on for too long.