{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7321-1FF81-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7321-1FF81-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7321-1FF81-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7321-1FF81-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 SM 321 digital input module, 6ES7321-1FF81-0AA0, 8 optically isolated inputs, 120/230 V AC, expanded temperature range, 20-pin front connector.","salesMarkdown":"## 8 AC inputs, expanded temp range — what the EOL status means for your BOM The Siemens 6ES7321-1FF81-0AA0 is an SM 321 digital input module for the S7-300 family, carrying 8 optically isolated inputs rated for 120/230 V AC (47...63 Hz) with an expanded temperature range. The signal \"1\" threshold spans 79 to 264 V AC, so it reads line-voltage AC signals directly — no external signal conditioner needed between a 120 V or 230 V sensor and the backplane. This module is flagged EOL/hot in the lifecycle record — the manufacturer has ended production and the part is in the last-time-buy window or already past it. For a BOM line that still calls out this order code, the sourcing path is surplus or broker channel, quoted per RFQ against the specific quantity. ## Signal thresholds and wiring constraints Each input draws 6.5 mA typ at 120 V and 11 mA typ at 230 V. The module accepts 2-wire proximity sensors with a permissible quiescent current up to 2 mA — above that the input may not see a clean \"0\" signal. The \"0\" signal range is 0 to 40 V, so a leaky sensor that sits above 40 V in its off-state will be read as a \"1\". Inputs are grouped in pairs (groups of 2) with optocoupler isolation between the channels and the backplane bus. Isolation is tested at 1500 V AC. The module requires a 20-pin front connector — that connector is ordered separately and determines the wiring topology for the field cables. Maximum cable length is 1000 m shielded, 600 m unshielded. The input filter delay from \"0\" to \"1\" is 25 ms max — enough to debounce mechanical contacts but too slow for a high-speed pulse train. ## Panel fit and power budget All 8 inputs can be active simultaneously at both 40 °C and 60 °C ambient — no derating needed within the standard S7-300 enclosure limits.","metaTitle":"Siemens 6ES7321-1FF81-0AA0 SM 321 8 DI, 120/230V AC","metaDescription":"SIMATIC S7-300 SM 321 digital input module, 8 inputs, 120/230V AC, expanded temp range. EOL/hot lifecycle. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Digital Input Modules"],"specifications":{"Depth":"120 mm","Width":"40 mm","Height":"125 mm","2-Wire Sensor":"Yes","For Signal \"0\"":"0 to 40V","For Signal \"1\"":"79 to 264V","Shielded, Max.":"1 000 m","Weight, approx.":"240 g","lifecycle_stage":"eol_hot","Power loss, typ.":"4.9 W","Rated value (AC)":"230 V; 120/230 V AC (47 ... 63 Hz)","Unshielded, Max.":"600 m","up to 40 °C, max.":"8","up to 60 °C, max.":"8","At \"0\" To \"1\", Max.":"25 ms","For Signal \"1\", Typ.":"6.5 mA; 6.5 mA (120 V); 11mA (230 V)","Isolation tested with":"1 500 V AC","Number of digital inputs":"8","Required Front Connector":"20-pin","from backplane bus 5 V DC, max.":"29 mA","Between The Channels, In Groups Of":"2","Between The Channels And Backplane Bus":"Yes; Optocoupler","Permissible Quiescent Current (2-Wire Sensor), Max.":"2 mA"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$116.84","priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=80839&mlfb=6ES7321-1FF81-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7321-1FF81-0AA0/alternatives.json"},"ai":{"faq":[],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7321-1FF81-0AA0","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/6ES7321-1FF81-0AA0 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}}