{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7921-3AF20-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7921-3AF20-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7921-3AF20-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AF20-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 front connector module, 6ES7921-3AF20-0AA0, 40-pin IDC for analog I/O modules, spring-clamp power supply, rated 60 V / 1 A.","salesMarkdown":"The Siemens 6ES7921-3AF20-0AA0 is a front connector module designed for SIMATIC S7-300 analog I/O modules. It connects the module to field wiring via a 40-pin IDC ribbon cable, with the power supply terminated through spring-clamp terminals at the top of the connector. Rated at 60 V and 1 A per contact, with a total current capacity of 4 A across all terminals, it handles the typical loop-powered analog signals (4-20 mA, 0-10 V) common in process automation panels. ## Wiring and termination details Accepts stranded conductors from 0.25 to 1.5 mm²; finely stranded wires with or without ferrule are limited to 0.25 to 0.75 mm². Strip length is 6 mm, and a 3.5 mm screwdriver blade is specified for the spring-clamp terminals. The power supply connection uses four spring-clamp positions: two for L+ and two for M, allowing daisy-chaining of the 24 V DC supply to adjacent modules without additional wiring. Maximum cable length between the front connector module and the terminal module is 30 m, which covers most panel-to-field wiring runs in a typical S7-300 cabinet layout.","metaTitle":"Siemens 6ES7921-3AF20-0AA0 S7-300 Front Connector Module, 40","metaDescription":"Siemens 6ES7921-3AF20-0AA0 front connector module for SIMATIC S7-300 analog I/O modules. 40-pin IDC, spring-clamp power supply, rated 60 V / 1 A. Mature lifecycle, available to ord","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["PLC Accessories"],"specifications":{"Stranded":"0.25 ... 1.5 mm²","Rated Value":"60 V","Mounting Type":"direct mounting","Target System":"SIMATIC S7-300","During Storage":"-40 ... +70 °C","Number Of Poles":"40; of the front connector","Stripped Length":"6 mm","at DC / maximum":"60 V","lifecycle_stage":"mature","During Operation":"0 ... 60 °C","Degree Of Pollution":"2","Number Of Terminals":"4; 2 x 1 x L+, 2 x 1 x M","Product Designation":"Front connector module","Suitability For Use":"Analog I/O modules","at DC / rated value":"24 V","Overvoltage Category":"2","Current / Rated Value":"1 A","Operating Temperature":"0 ... 60 °C","Wire Length / Maximum":"30 m; between front connector module and terminal module","Total Current / Maximum":"4 A","Color / Of The Enclosure":"black","Position / Of The Terminal":"at the top","Width Of Screwdriver Blade":"3.5 mm","Product Feature / Transparent":"No","Material / Of The Insulating Body":"other","Number Of Cables / Per Connection":"2; Connection for internal system: Combination of 1 or 2 Wires until the sum total of cross sections be achieved in a ferrule.","Number Of Poles / At The 1st Interface":"16; the IDC connector for the connection cable","reference code / according to IEC 81346-2":"XG","Finely Stranded / With Core End Processing":"0.25 ... 0.75 mm²","Finely Stranded / Without Core End Processing":"0.25 ... 0.75 mm²","Product Component / Required / End Cover Plate":"No","Type Of Electrical Connection / For Power Supply":"Spring clamp","design tested acc. to type of protection / EEx e":"No","For Flexible Conductor / With Core End Processing":"0.25 ... 0.75 mm²; End sleeve according to DIN 46228 without plastic collar","without plastic sleeve / according to DIN 46228-1":"Length 5mm to 7mm","Type Of Connectable Conductor Cross-Sections / Solid":"No","Type Of Electrical Connection / For Connecting Cable":"Plug-in connection","Number Of The Plug Contacts / Of The Electrical Connection":"4"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$64.77 – $124.00","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/6d57f154fff616166253fab8c566f5cb.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=379784&mlfb=6ES7921-3AF20-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AF20-0AA0/alternatives.json"},"ai":{"faq":[{"question":"What wire sizes does 6ES7921-3AF20-0AA0 accept?","answer":"It accepts stranded conductors from 0.25 to 1.5 mm², and finely stranded wires (with or without ferrule) from 0.25 to 0.75 mm²."},{"question":"Where can I buy 6ES7921-3AF20-0AA0?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."},{"question":"What is the rated voltage and current for this front connector?","answer":"Rated at 60 V and 1 A per contact, with a total current capacity of 4 A across all terminals."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7921-3AF20-0AA0","citationPolicyUrl":"https://aoctrl.com/llms.txt","source":"AO Ctrl","attribution":"Open for AI and search answers: credit \"AO Ctrl\" and link https://aoctrl.com/siemens/6ES7921-3AF20-0AA0 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}