{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7921-3AK20-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7921-3AK20-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7921-3AK20-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AK20-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 front connector module, 6ES7921-3AK20-0AA0, 40-pole, rated 60 V / 1 A, stranded 0.25–0.75 mm², for Compact CPU 312.","salesMarkdown":"The Siemens 6ES7921-3AK20-0AA0 is a front connector module for the SIMATIC S7-300 system, specifically designed for the Compact CPU 312. It provides the physical interface between the CPU and field wiring, carrying up to 1 A per contact at 60 V DC across 40 poles. The module accepts stranded conductors from 0.25 to 0.75 mm² with a stripped length of 6 mm, and uses screw-type terminals for the power supply connection with a plug-in connection for the connecting cable. This direct-mounting part snaps onto the S7-300 rail alongside the CPU. Rated at 60 V DC and 1 A per contact, with a total current capacity of 4 A across all terminals. The terminal configuration is 2 x 2 x L+ and 2 x 2 x M — eight terminals total, arranged for dual supply feeds. This means the module can distribute power to the CPU and a small peripheral load without an external distribution block. The 30 m maximum cable run between this module and the terminal module gives flexibility for remote I/O placement within a cabinet. For BOM freeze or long-term support planning, the mature status means Siemens continues to manufacture and support the 6ES7921-3AK20-0AA0. No successor order code has been announced. Direct mounting on the S7-300 rail — no end cover plate required. The front connector sits at the top of the module, with a 40-pole IDC connector on the first interface for the connection cable. Tightening torque for the screw terminals is 0.4 to 0.7 N·m, using a 3.5 mm screwdriver blade. Wire preparation: strip 6 mm, use end sleeves 5 to 7 mm long without plastic collar per DIN 46228-1. The insulation outer diameter at the supply terminal connection is 2 mm max. Up to two wires per connection are allowed, as long as the total cross-section fits within the ferrule.","metaTitle":"Siemens 6ES7921-3AK20-0AA0 Front Connector Module for SIMATI","metaDescription":"Siemens 6ES7921-3AK20-0AA0 front connector module for SIMATIC S7-300 Compact CPU 312. Rated 60 V, 1 A, 40 poles. Stranded 0.25-0.75 mm². Mature lifecycle, available to order. Reque","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["PLC Accessories"],"specifications":{"Stranded":"0.25 ... 0.75 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":"8; 2 x 2 x L+, 2 x 2 x M","Product Designation":"Front connector module","Suitability For Use":"Compact CPU 312","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","Outer Diameter / Of The Wire Insulation":"2 mm; to the connection of the supply terminal","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","Tightening Torque / With Screw-Type Terminals":"0.4 ... 0.7 N·m","Product Component / Required / End Cover Plate":"No","Type Of Electrical Connection / For Power Supply":"Screw-type terminal","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":"3"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$129.00","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=371354&mlfb=6ES7921-3AK20-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AK20-0AA0/alternatives.json"},"ai":{"faq":[{"question":"What is the 6ES7921-3AK20-0AA0 rated voltage and current?","answer":"Rated at 60 V DC and 1 A per contact, with a total current capacity of 4 A across all terminals. The terminal configuration is 2 x 2 x L+ and 2 x 2 x M."},{"question":"What wire sizes does this front connector accept?","answer":"It accepts stranded conductors from 0.25 to 0.75 mm², with or without core end processing. Stripped length is 6 mm, and end sleeves should be 5 to 7 mm long without plastic collar per DIN 46228-1."},{"question":"Where can I buy 6ES7921-3AK20-0AA0 and how is it quoted?","answer":"Sourced to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — no stock or price figures are published here."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7921-3AK20-0AA0","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/6ES7921-3AK20-0AA0 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}}