Hi, I've had my Interact a year or so now, and got everything working as a standard 3 axis machine. I 'won' a 4th axis on eBay recently, and started to have a look at integrating it into my machine. I have all the other parts, choke, servo card, and the Amphenol connectors all ready to go in. I thought I would test the 4th axis encoder on my lathe's Heidenhain VRZ, as the 11uA interface is the same - well the bulb in the 4th axis encoder is blown - annoying as the seller listed it as all working . I can however put a spare ERO115-125 on a SEM servo I have into the Lathe DRO and it registers fine when you turn the spindle.

So over to the mill, I connect the spare encoder to axis IV and change MP76 to 1 to show inhibited axis. I now see a 'B' on the TNC151 display, but moving the encoder does not change the 'B' count. So next I disable the X axis by setting MP72=9, and connect the spare encoder in place of the X-axis encoder, at power up, it asks to only ref Y and Z, as expected. Now if I rotate the spare encoder the X-axis registers the movement.

So my question is : Is my 4th axis encoder input on my TNC151 broken?

I've take the TNC151 out of the interact, and removed the card, I check the connector from the back of the TNC to the card on the 4th axis - all good. All four channels look to have the same layout of circuitry, but swapping the physical encoder circuits over looks non-trivial, so I may have to start by swapping over all the ICs between channel 4 and one working one until I find the guilty party.

Please someone tell me there is a magic jumper someplace to enable the 4th axis, or some Machine parameter I have overlooked!

Regards, Hazel