{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7921-3AG20-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7921-3AG20-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7921-3AG20-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AG20-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 front connector module, 6ES7921-3AG20-0AA0, 40-pole, 60 V, screw-type terminals, flat ribbon cable connection for analog I/O modules.","salesMarkdown":"## What this front connector does on an S7-300 rack The Siemens 6ES7921-3AG20-0AA0 is a 40-pole front connector module that bridges the flat ribbon cable from an analog I/O module to the screw terminals on the SIMATIC S7-300. Rated at 60 V and 1 A per contact, with a total current capacity of 4 A across all terminals, it handles the signal-level wiring for analog inputs and outputs without taxing the backplane. The screw terminals accept stranded wire from 0.25 to 1.5 mm², stripped to 6 mm, torqued between 0.4 and 0.7 N·m — standard panel-builder practice for 24 V control loops. This module is designed specifically for analog I/O modules in the S7-300 system, not for digital or mixed-signal racks. The 40-pole IDC connector at the first interface mates with the flat ribbon cable, while the 4-pole plug-in connection on the other side feeds power through screw terminals — two for L+ and two for M, supporting up to two conductors per connection with ferruled ends. ## Wiring and mounting on the rail Mounts directly onto the S7-300 rail — no end cover plate required. The terminals sit at the top, which keeps the wiring accessible when the module is stacked between I/O blocks. Screwdriver blade width is 3.5 mm for the screw-type terminals. For fine-stranded wire with core-end processing, the range narrows to 0.25 to 0.75 mm² with an end sleeve per DIN 46228 without a plastic collar, trimmed to 5–7 mm. Solid wire is not supported, so plan for ferruled stranded throughout. The maximum cable run between this front connector module and the terminal module is 30 m — plenty for routing within a standard panel enclosure.","metaTitle":"Siemens 6ES7921-3AG20-0AA0 Front Connector Module, 40-Pole,","metaDescription":"Siemens 6ES7921-3AG20-0AA0 front connector module for SIMATIC S7-300 analog I/O. 40-pole, 60 V rated, screw terminals, flat ribbon cable connection. Mature lifecycle, sourced to or","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","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":"4"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$59.03 – $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=276043&mlfb=6ES7921-3AG20-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7921-3AG20-0AA0/alternatives.json"},"ai":{"faq":[{"question":"What wire sizes does this front connector accept?","answer":"Stranded wire from 0.25 to 1.5 mm² for the screw terminals, with a stripped length of 6 mm. For fine-stranded wire with ferruled ends, the range is 0.25 to 0.75 mm² using end sleeves per DIN 46228 without plastic collar, trimmed to 5–7 mm."},{"question":"What is the rated voltage and current for 6ES7921-3AG20-0AA0?","answer":"Rated voltage is 60 V DC, with a rated current of 1 A per contact and a total maximum current of 4 A across all terminals. The 24 V DC rating covers standard S7-300 control supply."},{"question":"Where can I buy 6ES7921-3AG20-0AA0 and how is it quoted?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution channels. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm quote on your volume."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7921-3AG20-0AA0","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/6ES7921-3AG20-0AA0 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}}