{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7921-5CH20-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7921-5CH20-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7921-5CH20-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7921-5CH20-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-1500 front connector module, 6ES7921-5CH20-0AA0, 40-pole, push-in terminals, 24 V rated, 2 A max, for digital I/O modules.","salesMarkdown":"The Siemens 6ES7921-5CH20-0AA0 is a 40-pole front connector module for SIMATIC S7-1500 digital I/O modules. It carries the 24 V rated supply and signal wiring from the I/O module to the field via a 50-pole IDC connector on the cable side and push-in terminals on the power side. This is the piece that bridges the S7-1500 backplane to your field terminations — no rewiring the rack when you swap a module. ## Key specs that matter for fit Accepts stranded wire from 0.5 to 1.5 mm², with a stripped length of 8 mm. The push-in terminals on the power supply side take a 3.5 mm screwdriver blade. Rated for 24 V DC, with a maximum total current of 2 A in horizontal mounting position. Maximum wire run between the front connector module and the terminal module is 30 m — plan your cabinet layout within that. Pollution degree 2, overvoltage category II — standard for clean, controlled environments like a panel or enclosure. Mounts directly on the S7-1500 I/O module — no DIN rail or end cover plate required. The 40 poles handle up to 32 digital I/O points plus power. Terminals sit at the top of the module; the IDC cable exits the front. Keep the 30 m cable length limit in mind when routing to a remote terminal block.","metaTitle":"Siemens 6ES7921-5CH20-0AA0 Front Connector Module, SIMATIC S","metaDescription":"Siemens 6ES7921-5CH20-0AA0 front connector module for SIMATIC S7-1500 digital I/O. 40-pole, push-in terminals, 24 V rated, 2 A max. Mature lifecycle. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["PLC Accessories"],"specifications":{"Stranded":"0.5 ... 1.5 mm²","Rated Value":"24 V","Mounting Type":"direct mounting","Target System":"SIMATIC S7-1500","During Storage":"-40 ... +70 °C","Number Of Poles":"40; of the front connector","Stripped Length":"8 mm","at DC / maximum":"60 V","lifecycle_stage":"mature","During Operation":"0 ... 60 °C","Degree Of Pollution":"2","Number Of Terminals":"4; 4 x 1 x L+","Product Designation":"Front connector module","Suitability For Use":"Digital I/O modules","at DC / rated value":"24 V","Overvoltage Category":"2","Operating Temperature":"0 ... 60 °C","Wire Length / Maximum":"30 m; between front connector module and terminal module","Total Current / Maximum":"2 A; for mounting position horizontal","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":"50; the IDC connector for the connection cable","Outer Diameter / Of The Wire Insulation":"3.1 mm; to the connection of the supply terminal","reference code / according to IEC 81346-2":"XG","Finely Stranded / With Core End Processing":"0.25 ... 1.5 mm²","Finely Stranded / Without Core End Processing":"0.5 ... 1.5 mm²","Product Component / Required / End Cover Plate":"No","with plastic sleeve / according to DIN 46228-4":"Length 8mm to 9mm","Type Of Electrical Connection / For Power Supply":"Push-In terminal","design tested acc. to type of protection / EEx e":"No","For Flexible Conductor / With Core End Processing":"0.25 ... 1.5 mm²; End sleeve according to DIN 46228/1 or DIN 46228/4 with plastic collar max. 0.75 mm2","without plastic sleeve / according to DIN 46228-1":"Length 8mm to 9mm","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":"1"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$40.64 – $104.00","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=418022&mlfb=6ES7921-5CH20-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7921-5CH20-0AA0/alternatives.json"},"ai":{"faq":[{"question":"What wire sizes does 6ES7921-5CH20-0AA0 accept?","answer":"Stranded wire from 0.5 to 1.5 mm², with a stripped length of 8 mm. Finely stranded with core-end processing accepts 0.25 to 1.5 mm²."},{"question":"What is the rated voltage and current for this front connector?","answer":"Rated voltage is 24 V DC, with a maximum total current of 2 A in horizontal mounting position."},{"question":"Where can I buy 6ES7921-5CH20-0AA0?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing confirmed at quote time."},{"question":"Will 6ES7921-5CH20-0AA0 work with 3RH2122-1WB40?","answer":"No — 3RH2122-1WB40 is a Siemens contactor relay, not an S7-1500 front connector. This module is specific to SIMATIC S7-1500 digital I/O modules and has no cross-compatibility with contactor wiring."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7921-5CH20-0AA0","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/6ES7921-5CH20-0AA0 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}}