We have a Mazak FH4800 that has a load area safety curtain system made by Sunx. We are looking into retrofitting the SunX curtain system with a Banner USCD 1T2 style due to having an abundance of Banners on hand and difficulty with obtaining the Sunx's.

The Sunx reports a safe condition by activating a NC relay, thus opening a 24vdc loop path back to the I/O of the Mazak. The problem I have is that the Banner substitute only has NO relays contacts for this purpose. I thought about adding relays to the circuit to reverse this but there is no way for the USCD to monitor these for a failure condition, which would be required for a legitimate safety installation.

What I'm wondering about doing is reversing the logic in the Mazak ladder so that instead of seeing safe as an open loop, it will see it as closed. The curtain system's relay contacts apparently go right into an I/O extension of the Mazak control and not a safety control as might be expected. I would think it should be as simple as changing a ladder rung XIC to XIO or vice versa. As it is, I don't know enough about the Mazak to find and edit the ladder. Can anyone offer any guidance?