{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7321-1EH01-0AA0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7321-1EH01-0AA0","canonicalUrl":"https://aoctrl.com/siemens/6ES7321-1EH01-0AA0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7321-1EH01-0AA0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-300 SM 321, Digital Input Module, 6ES7321-1EH01-0AA0, 16 DI, 120 VAC, optically isolated, 20-pin front connector.","salesMarkdown":"## 16 inputs at 120 VAC — the AC-input S7-300 slice The Siemens 6ES7321-1EH01-0AA0 is a SIMATIC S7-300 SM 321 digital input module with 16 optically isolated channels, each rated for 120 VAC input at 47 to 63 Hz. The 1-signal threshold is 79 to 132 VAC, and the 0-signal threshold is 0 to 20 VAC — so a standard 120 VAC control voltage from a pushbutton or limit switch lands solidly in the ON region, while a dropped neutral or a 24 VAC pilot signal stays OFF. ## Isolation groups and wiring reality The 16 inputs are isolated from the backplane bus in groups of 4, meaning four adjacent channels share a common reference point; you cannot mix different AC phases or a separate control transformer within the same group without bridging the isolation barrier. The module uses a 20-pin front connector — the same pinout as other S7-300 SM 321 AC-input slices — so a pre-wired harness or a replacement module swaps in without re-terminating the field wiring. ## End-of-life — sourcing the 6ES7321-1EH01-0AA0 No official successor order code is listed in the lifecycle data, so the replacement path is either a newer S7-300 SM 321 variant (verify the input voltage and isolation group count) or a migration to the S7-1200 / S7-1500 platform with a different form factor and wiring scheme.","metaTitle":"Siemens 6ES7321-1EH01-0AA0 SM 321, 16 DI, 120 VAC, EOL","metaDescription":"Siemens SIMATIC S7-300 SM 321 digital input module, 16 optically isolated inputs, 120 VAC, 47-63 Hz. End-of-life — sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Digital Input Modules"],"specifications":{"MRN":"6ES7321-1EH01-0AA0","Type":"Digital Input Module","Model":"6ES7 321-1EH01-0AA0","Family":"SIMATIC S7-300","Weight":"0.27 kg","Condition":"Used","Frequency":"47 … 63 Hz","Shelf No.":"210501","Rated Value":"120 VAC","Manufacturer":"SIEMENS","lifecycle_stage":"eol_hot","Number of Inputs":"16","for “0” Signal":"0 … 20 V","for “1” Signal":"79 … 132 V","Isolation (to Backplane Bus) in Groups of":"4"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=347333&mlfb=6ES7321-1EH01-0AA0","alternativesUrl":"https://aoctrl.com/api/mcp/products/6ES7321-1EH01-0AA0/alternatives.json"},"ai":{"faq":[{"question":"How many inputs does 6ES7321-1EH01-0AA0 have?","answer":"16 digital inputs, optically isolated, rated for 120 VAC."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7321-1EH01-0AA0","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/6ES7321-1EH01-0AA0 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}}