I looked at the latching and bi-state relays and diagramed out how it would work and the code. I now think that the BOB (PMDX 125) SPDT Mechanical relay would be the simplest solution. The NC terminals would signal clamp, and always default to clamp. The power could come from either on, or off, the board as needed. Trusty spring, one Pin, one output, two M codes. Seems too simple but simple is always good, Thanks all, Edward