{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7421-1BL01-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7421-1BL01-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7421-1BL01-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7421-1BL01-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-400, SM 421 digital input module, 32 isolated 24 V DC inputs, type 1 per IEC 61131, 25 mm width, 290 mm height, 210 mm depth, approx. 500 g.","salesMarkdown":"The Siemens 6ES7421-1BL01-0AA0 is a SIMATIC S7-400 SM 421 digital input module providing 32 isolated inputs rated for 24 V DC, compliant with IEC 61131 type 1 input characteristic. It accepts 2-wire sensors and defines signal \"0\" from -30 V DC to +5 V DC and signal \"1\" from 13 V DC to 30 V DC, with a typical signal \"1\" current of 7 mA. The module draws 20 mA from the 5 V DC backplane bus and dissipates 6 W typical power loss. ## Deployment and integration This module occupies one slot in the S7-400 rack (25 mm wide, 290 mm high, 210 mm deep) and connects via the backplane bus. All 32 inputs are simultaneously controllable; no channel-to-channel isolation is provided, but the input group (all 32) is isolated from the backplane bus. The isolation is tested at 500 V AC / 707 V DC, type test. Status indicators (green LEDs) are present per digital input. ## Input timing and sensor compatibility Input filtering is configurable within a range: transition from \"0\" to \"1\" takes 1.2 ms minimum to 4.8 ms maximum; \"1\" to \"0\" similarly 1.2 ms to 4.8 ms. This covers both fast and debounced sensing. For 2-wire sensors, the permissible quiescent current at signal \"0\" is max. 1.3 mA, and the overall permissible quiescent current is max. 1.5 mA — exceeding these will cause false \"1\" detection. Unshielded cable runs up to 600 m; shielded up to 1 000 m. This part carries a lifecycle status of NRND (Not Recommended for New Designs) per the manufacturer, with a maturity stage of \"mature\".","metaTitle":"Siemens 6ES7421-1BL01-0AA0 SM 421 DI Module, 32 Inputs, 24 V","metaDescription":"SIMATIC S7-400 SM 421 digital input module, 32 isolated 24 V DC inputs, type 1 per IEC 61131. NRND — sourced to order. Quoted against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"NRND","categoryPath":["Digital Input Modules"],"specifications":{"Depth":"210 mm","Width":"25 mm","Height":"290 mm","2-Wire Sensor":"Yes","For Signal \"0\"":"-30 V DC to +5 V DC","For Signal \"1\"":"13 V DC to 30 V DC","Shielded, Max.":"1 000 m","Weight, approx.":"500 g","lifecycle_stage":"mature","Power loss, typ.":"6 W","Rated value (DC)":"24 V","Unshielded, Max.":"600 m","At \"0\" To \"1\", Max.":"4.8 ms","At \"0\" To \"1\", Min.":"1.2 ms","At \"1\" To \"0\", Max.":"4.8 ms","At \"1\" To \"0\", Min.":"1.2 ms","Between The Channels":"No","Diagnostics function":"No","For Signal \"1\", Typ.":"7 mA","Isolation tested with":"500 V AC/707 V DC, type test","Type of input voltage":"DC","Number of digital inputs":"32","from backplane bus 5 V DC, max.":"20 mA","Between The Channels, In Groups Of":"32","Between The Channels And Backplane Bus":"Yes","Status indicator digital input (green)":"Yes","Input characteristic according to IEC 61131":"Type 1","Number of simultaneously controllable inputs":"32","Permissible Quiescent Current (2-Wire Sensor), Max.":"1.5 mA","For Signal \"0\", Max. (Permissible Quiescent Current)":"1.3 mA"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$167.00 – $305.99","priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/1ada08b38644c20c7fc20b709c03661d.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=4496&mlfb=6ES7421-1BL01-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7421-1BL01-0AA0/alternatives.json"},"ai":{"faq":[{"question":"Where can I buy 6ES7421-1BL01-0AA0 and get a price?","answer":"This part is sourced to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time — submit an RFQ for a firm commercial response."},{"question":"What is the closest functional second-source for 6ES7421-1BL01-0AA0?","answer":"The peer modules 6ES7513-1AL01-0AB0, 6ES7511-1AK02-0AB0, and 6ES7511-1AL03-0AB0 are from the S7-1500 family and are not form-fit-function replacements for the S7-400 SM 421. They require a different rack, backplane, and configuration environment (TIA Portal vs. STEP 7). No direct drop-in substitute exists without panel rewiring and a controller migration."},{"question":"What is 6ES7421-1BL01-0AA0's listed depth?","answer":"The module depth is 210 mm, with a width of 25 mm and height of 290 mm."},{"question":"Will 6ES7421-1BL01-0AA0 drop into a panel specified around 6ES7513-1AL01-0AB0?","answer":"No — the 6ES7513-1AL01-0AB0 is an S7-1500 CPU (129 mm depth, 35 mm width, 147 mm height) with a different rack, backplane, and mounting footprint. The SM 421 module cannot be physically or electrically installed in an S7-1500 rack without significant panel modification and a controller migration."},{"question":"What compliance documentation does Siemens provide for 6ES7421-1BL01-0AA0?","answer":"The module is designed to meet IEC 61131 type 1 input characteristics and carries a type-test isolation rating of 500 V AC / 707 V DC. Standard Siemens declarations of conformity for CE, UKCA, and RoHS/REACH are available via the manufacturer's support portal for this order code."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7421-1BL01-0AA0","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/6ES7421-1BL01-0AA0 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}}