{"product_id":"kl4021-beckhoff-1-channel-analog-output-terminal-4-20-ma","title":"KL4021 | BECKHOFF | Terminal de sortie analogique 1 canal 4-20 mA","description":"\u003ch3\u003eProduct Overview\u003c\/h3\u003e\n\u003cp\u003eThe\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021 (KL4021)\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eis a precision 1-channel analog output terminal designed for the Beckhoff Bus Terminal system, delivering a standardized 4 to 20 mA current signal. Engineered for high-reliability process control, this module is the industry standard for interfacing with proportional valves, dampers, and frequency inverters in water treatment, HVAC, and chemical processing plants. With its 12-bit resolution and a low output error of less than ±0.1 percent, the\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eensures stable and repeatable actuator positioning. Its robust design is further validated by extensive marine (DNV GL) and hazardous area (ATEX\/IECEx) certifications, making it a versatile choice for both onshore industrial sites and offshore installations.\u003c\/p\u003e\n\u003ch3\u003eTechnical Configuration\u003c\/h3\u003e\n\u003cp\u003eThe hardware architecture of the\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eis optimized for the K-bus protocol, featuring a single-ended 1-wire connection technology. The terminal draws its 24 VDC supply via the internal power contacts, though it optionally supports 15 VDC operation when used with a KL9515 power supply terminal for specific energy-efficient or legacy requirements. The module provides 500 V electrical isolation between the internal K-bus logic and the field signal voltage, safeguarding the central controller from field-side electrical surges. The process image is presented as a 1 x 16-bit data value, and the unit is designed for \"plug-and-play\" operation, requiring no complex hardware addressing or manual configuration settings.\u003c\/p\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr class=\"firstRow\"\u003e\n\u003ctd\u003e\u003cstrong\u003eFeature\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eSpecification\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eModel\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eKL4021\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eBrand\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eBECKHOFF\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eOrigin\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eGermany\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eNumber of Outputs\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e1\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eSignal Current\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e4 to 20 mA\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eResolution\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e12 bit\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eLoad\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e\u0026lt; 500 Ohms\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eConversion Time\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eapprox. 1.5 ms\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eOutput Error\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e\u0026lt; +\/- 0.1 percent (relative to end value)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eElectrical Isolation\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e500 V (K-bus \/ signal voltage)\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eCurrent Consumption (K-bus)\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003etyp. 60 mA\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eOperating Temperature\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003e0 to +55 Celsius\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cspan\u003e\u003cstrong\u003eApprovals\u003c\/strong\u003e\u003c\/span\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cspan\u003eCE, UL, ATEX, IECEx, DNV GL\u003c\/span\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eTechnical FAQs\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eCan I use the KL4021 for a 0-20 mA application?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eis hardware-optimized for 4-20 mA to provide \"live-zero\" monitoring. For applications strictly requiring 0-20 mA, you should select the KL4011. Using the KL4021 for 0-20 mA would result in the inability to output signals below 4 mA.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the maximum distance the current signal can travel?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eBecause the 4-20 mA signal is a current loop, it is highly resistant to voltage drops and EMI. The distance is primarily limited by the total loop resistance; as long as the total resistance (wire + actuator) remains under 500 Ohms, the terminal will maintain its specified accuracy over several hundred meters.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow do the 12-bit resolution and 16-bit process image interact?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe 12-bit output value is mapped into the 16-bit data word of the K-bus. Typically, the value is left-aligned. In your PLC program, you will scale your process variable (e.g., 0-100%) to the corresponding digital range (typically 0 to 32767 or 4095 depending on configuration) to drive the output.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3\u003eEngineering \u0026amp; Installation Guide\u003c\/h3\u003e\n\u003cul class=\"list-paddingleft-2\"\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eShielding for Precision:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eAlthough 4-20 mA is robust, for the highest accuracy (especially in maritime or Ex zones), use shielded twisted-pair (STP) cables. Connect the shield at only one end—typically at the control cabinet's earth bar—to prevent ground loops from introducing signal offsets.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eLoad Matching:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eVerify that your actuator's input impedance does not exceed 500 Ohms. If the load is too high, the terminal will be unable to drive the full 20 mA, resulting in a \"saturated\" output that does not match your PLC command.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003ePower Supply Stability:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eWhile the terminal can run on 24 VDC via power contacts, ensure your power supply has sufficient headroom. The\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003econsumes roughly 30 mA plus the actual loop current (up to 20 mA). In a large terminal strand, calculate the total current to ensure the bus coupler’s power contacts (max 10 A) are not overloaded.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cp\u003e\u003cstrong\u003eHazardous Area Mounting:\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003eFor ATEX\/IECEx Zone 2 compliance, the\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eKL4021\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003emust be installed in an enclosure providing at least IP54 protection. Ensure that all wiring is secured against accidental disconnection, as per the \"Ex nA\" and \"Ex ec\" safety requirements.\u003c\/p\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"BECKHOFF","offers":[{"title":"Default Title","offer_id":53106672009579,"sku":"KL4021","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0953\/3227\/0443\/files\/kl4021-1qwnsnf4l2j.png?v=1776245166","url":"https:\/\/www.plcprotech.com\/fr\/products\/kl4021-beckhoff-1-channel-analog-output-terminal-4-20-ma","provider":"PLC ProTech Ltd.","version":"1.0","type":"link"}