MTL1211 Switch/Proximity Detector. MTL1211 is a 1 channel switch or proximity detector isolator that has the ability to select line fault detection or repeat output. The signal conditioner is DIN Rail mountable. Features and Benefits. 1 Channel switch/proximity detector with line fault detection Switches are used to select phase reversal or the repeat output Power supplied via power bus embedded in the DIN Rail LED indicators for fault detection DIN Rail mounting