{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7921-3AA20-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7921-3AA20-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7921-3AA20-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AA20-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 front connector module, 6ES7921-3AA20-0AA0, 40-pole with flat ribbon cable connection for digital 32 I/O modules, spring-clamp power supply terminals, rated 60 V DC, 1 A per channel.","salesMarkdown":"## What this front connector module does The Siemens 6ES7921-3AA20-0AA0 is a front connector module purpose-built for the SIMATIC S7-300 platform, specifically to connect digital 32 I/O modules via a flat ribbon cable. It carries 40 poles on the front connector side, with 8 terminals arranged as 4 x 1 x L+ and 4 x 1 x M for the power supply, which uses spring-clamp connections rated at 60 V DC and 1 A per channel. Total current through the module caps at 4 A, so it's sized for moderate I/O banks — not high-current field wiring. ## Wire sizing and termination Terminals accept stranded wire from 0.25 to 0.75 mm², with a stripped length of 6 mm. For finely stranded conductors with core-end processing, use end sleeves per DIN 46228 without plastic collar, trimmed to 5–7 mm. The spring-clamp power supply connection handles up to two wires per terminal, provided the sum of cross-sections fits within a single ferrule. A 3.5 mm screwdriver blade width is specified for the clamping mechanism. ## Environmental limits and installation The module is rated for overvoltage category II and pollution degree 2, which covers normal industrial control cabinet environments — not outdoor or washdown locations. It mounts directly onto the S7-300 rail, with the terminals positioned at the top. Maximum cable length between the front connector module and the terminal module is 30 m. This part is classified as mature in its lifecycle, meaning it's an established, stable product — not recently introduced, but still actively supported within the S7-300 ecosystem.","metaTitle":"Siemens 6ES7921-3AA20-0AA0 Front Connector Module for S7-300","metaDescription":"Siemens SIMATIC S7-300 front connector module with flat ribbon cable connection for digital 32 I/O modules. Rated 60 V DC, 1 A per channel. Spring-clamp power supply terminals. Mat","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; 4 x 1 x L+, 4 x 1 x M","Product Designation":"Front connector module","Suitability For Use":"Digital 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","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","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":"$56.35 – $118.00","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=6572&mlfb=6ES7921-3AA20-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AA20-0AA0/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy 6ES7921-3AA20-0AA0 and how do I get a price?","answer":"This part is sourced to order against an RFQ through independent distribution. Submit a request for quote to confirm current availability and pricing — no stock or price figures are published here."},{"question":"What wire sizes does the 6ES7921-3AA20-0AA0 accept?","answer":"The spring-clamp terminals accept stranded wire from 0.25 to 0.75 mm², with a stripped length of 6 mm. For finely stranded conductors, use end sleeves per DIN 46228 without plastic collar."},{"question":"What is the rated voltage of the 6ES7921-3AA20-0AA0?","answer":"The rated voltage is 60 V DC, with a rated current of 1 A per channel and a total current maximum of 4 A across the module."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7921-3AA20-0AA0","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/6ES7921-3AA20-0AA0 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}}