Product Description:

The KL3311 analog input module is produced by Beckhoff for the KL Analog Input Modules series. It accepts a single thermocouple channel and digitizes the temperature so that a controller can monitor heating zones, drying ovens, or process vessels. By integrating the A/D converter, cold-junction sensor, and field wiring into one terminal, the module simplifies temperature feedback loops on DIN-rail I/O stations that interface with distributed PLC or PC-based automation. In industrial automation, this part delivers temperature data in normalized engineering units over the K-bus, allowing precise thermal regulation without separate instrumentation.

The measurement section uses internal temperature measurement for cold-junction compensation, eliminating external references when Type K thermocouples are used. Field wiring follows a two-wire scheme, and the terminal provides a single input, making channel assignment clear during setup. After conversion, process data are placed on the K-bus with a width of 1 × 16 bits, while an additional 1 × 8 bits can be appended for optional status information such as sensor-break flags. The measurement resolution is 0.1 °C per digit, so a ten-degree span is represented by 100 increments. Under calibrated conditions, the total measuring error stays within ±0.5% FS, providing suitable accuracy for most thermal control loops.

The terminal clips onto a 35 mm DIN rail, and its installation position is variable, so it can be mounted horizontally or vertically without derating. Operating power is supplied through the K-bus, removing the need for separate auxiliary power leads. The bus watchdog can reset the channel if no fresh control data arrive within 100 ms. The electronics have an IP20 enclosure rating, limiting use to cabinets while providing finger-safe terminals. An automatic open-circuit detection routine raises a flag when the thermocouple loop is interrupted, helping prevent uncontrolled heating.