Heating-Cooling Relay with 4 channels, each with 1 normally open contact rated for 4A/250V AC, isolated from the supply voltage, featuring DX technology. Bidirectional. Standby loss is only 0.1 watts. Rail-mounted device for installation on DIN-EN 60715 TH35 mounting rails. 1 unit width = 18 mm, depth 58 mm. Connection to the Eltako RS485 bus. Cross-wiring for bus and power supply with jumper. With the patented Eltako Duplex technology, the normally potential-free contacts can still switch at the zero crossing when switching 230V AC 50Hz, significantly reducing wear. Simply connect the neutral conductor to terminal (N) and the live conductor to (L). This results in an additional standby loss of only 0.1 watts. When all 4 relays are activated, 0.7 watts are required. In the event of a power failure, it will be turned off in a defined manner. This heating-cooling relay evaluates information from radio temperature controllers or sensors, possibly supplemented by window-door contacts, motion detectors, window handle sensors FFG7B, and radio buttons. As an alternative to a radio temperature controller, temperature information can also be obtained from a controller based on set and actual values. Furthermore, there is the option to set the desired temperature via the controller, thereby limiting the adjustment range of the radio temperature controllers. The upper rotary switch is for adjustable hysteresis: left stop: smallest hysteresis 0.5º. Middle position: hysteresis 2.5º. Right stop: largest hysteresis 4.5º. Intermediate divisions in 0.5º steps. The middle rotary switch is for control modes: AUTO 1: With PWM control with T = 4 minutes (PWM = Pulse Width Modulation). (Suitable for valves with thermoelectric actuators). AUTO 2: With PWM control with T = 15 minutes. (Suitable for valves with motorized actuators). AUTO 3: With 2-point control. The lower rotary switch is for operating modes: H: Heating mode (contacts 1 to 4).