{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"6ES7551-1AB01-0AB0","brand":"Siemens","brandSlug":"siemens","productSlug":"6ES7551-1AB01-0AB0","canonicalUrl":"https://aoctrl.com/siemens/6ES7551-1AB01-0AB0","factsUrl":"https://aoctrl.com/api/mcp/products/6ES7551-1AB01-0AB0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SIMATIC S7-1500, Counter Module 6ES7551-1AB01-0AB0, RS-422, 32 Input Bytes, 24 Output Bytes, 70 °C.","salesMarkdown":"The Siemens 6ES7551-1AB01-0AB0 is a counter/position-detection module for the S7-1500 rack, accepting incremental and absolute encoders via RS-422 or 5 V TTL push-pull. It provides 32 input bytes (16 per channel, 4 in fast mode) and 24 output bytes (12 per channel, 4 reserved for motion control). Runs on 5.2 V ±2 % from the backplane and 24 V via L+ (-0.8 V); the module draws its isolated sensor supply from the rack. Ambient range -40 to 70 °C covers cabinet installations from cold storage to panel interiors. ## Encoder interface and capture Accepts RS-422 differential signals for high-speed incremental encoders and 5 V TTL push-pull for single-ended types. Supports both binary and gray code absolute encoders with multiturn and singleturn resolution. Input impedance between 48 Ω and 12 kΩ. Fast mode reduces input data to 4 bytes per channel for tighter cycle times. Monoflop time selectable from 16 µs to 64 µs or automatic. Software gate and gate start/stop allow synchronized counting; synchronization supported for pulse and incremental encoders only. Diagnostic LEDs: RUN (green), ERROR (red), MAINT (yellow). Wire-break detection is built in. I&M data up to I&M3 for asset tracking.","metaTitle":"Siemens 6ES7551-1AB01-0AB0 Counter Module, 70°C","metaDescription":"Current-production Siemens counter module for S7-1500. RS-422 inputs, 32 bytes, -40 to 70°C. 5 V and 24 V supplies. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["PLC Communication Modules"],"specifications":{"5 V":"Yes; 5.2 V ±2 %","24 V":"Yes; L+ (-0.8 V)","Max.":"70 °C","Min.":"-40 °C","Depth":"129 mm","Width":"35 mm","title":"6ES7551-1AB01-0AB0","Height":"147 mm","Inputs":"32 byte; 16 bytes per channel; 4 bytes for fast mode","RS 422":"Yes","Capture":"Yes","Counter":"Yes","Outputs":"24 byte; 12 bytes per channel; 4 bytes for Motion Control, 0 bytes for fast mode","RUN LED":"Yes; green LED","TTL 5 V":"Yes; push-pull encoders only","I&M data":"Yes; I&M0 to I&M3","ERROR LED":"Yes; red LED","Fast mode":"Yes","Gray code":"Yes","MAINT LED":"Yes; Yellow LED","Multiturn":"Yes","Singleturn":"Yes","Wire-break":"Yes","Binary code":"Yes","Lower Limit":"48 Ω","Upper Limit":"12 kΩ","description":"SIMATIC S7-1500, TM PosInput 2 counter and position detection module for RS-422 incremental encoder or SSI absolute encoder, 2 channels, 2 DI, 2 DQ per channel","Input signal":"to RS-422","Input voltage":"5 V TTL (push-pull encoders only)","Monoflop time":"16, 32, 48, 64 µs & automatic","Pulse Encoder":"Yes","Rail mounting":"Yes; S7-1500 mounting rail","Short-circuit":"Yes","Software gate":"Yes","For Signal \"0\"":"-5 ... +5 V","For Signal \"1\"":"+11 to +30V","Shielded, Max.":"1 000 m","Gate start/stop":"Yes; only for pulse and incremental encoders","Parameterizable":"Yes","Synchronization":"Yes; only for pulse and incremental encoders","Weight, approx.":"325 g","lifecycle_stage":"current","\"0\" To \"1\", Max.":"50 µs","\"1\" To \"0\", Max.":"50 µs","Diagnostic alarm":"Yes","Firmware version":"V2.0","Isochronous mode":"Yes","Power loss, typ.":"5.5 W","Rated value (DC)":"24 V","Unshielded, Max.":"600 m","Number of outputs":"4; One 5V and 24V encoder supply per channel","to SIMATIC S7-300":"Yes","to SIMATIC S7-400":"Yes","FW update possible":"Yes","Hardware interrupt":"Yes","Number of channels":"2","Number of counters":"2","On Lamp Load, Max.":"10 Hz","to SIMATIC S7-1200":"Yes","to SIMATIC S7-1500":"Yes","At \"0\" To \"1\", Min.":"6 µs; for parameterization \"none\"","At \"1\" To \"0\", Min.":"6 µs; for parameterization \"none\"","Continuous counting":"Yes","Absolute acquisition":"Yes","Between The Channels":"No","Direction dependency":"Yes","For Signal \"1\", Min.":"23.2 V; L+ (-0.8 V)","For Signal \"1\", Typ.":"2.5 mA","Output current, max.":"300 mA; Per channel","Velocity measurement":"100 ppm; depending on measuring interval and signal evaluation","Clock frequency, max.":"2 MHz; 125 kHz, 250 kHz, 500 kHz, 1 MHz, 1.5 MHz or 2 MHz","Event-controlled stop":"Yes","Frequency measurement":"100 ppm; depending on measuring interval and signal evaluation","Input frequency, max.":"1 MHz","Isolation tested with":"707 V DC (type test)","Number of comparators":"2; Per channel","Type of input voltage":"DC","Channel status display":"Yes; green LED","Type of digital output":"Transistor","Type of output voltage":"DC","For Channel Diagnostics":"Yes; red LED","Incremental acquisition":"Yes","Counting frequency, max.":"4 MHz; with quadruple evaluation","Current per module, max.":"2 A","Number of digital inputs":"4; 2 per channel","Response threshold, typ.":"1 A","Short-circuit protection":"Yes; electronic/thermal","Current consumption, max.":"75 mA; without load","Number of digital outputs":"4; 2 per channel","With Inductive Load, Max.":"0.5 Hz; Acc. to IEC 60947-5-1, DC-13; observe derating curve","With Resistive Load, Max.":"10 kHz","Cycle duration measurement":"100 ppm; depending on measuring interval and signal evaluation","For Signal \"1\" Rated Value":"0.5 A; Per digital output","Controlling a digital input":"Yes","Freely usable digital input":"Yes","Frequency measurement, max.":"4 MHz","Frequency measurement, min.":"0.04 Hz","Parity bit, parameterizable":"Yes","Reverse polarity protection":"Yes","Vertical Installation, Max.":"40 °C; Please note derating for inductive loads","Vertical Installation, Min.":"-30 °C","to standard PROFIBUS master":"Yes","Cable length, shielded, max.":"320 m; Cable length, RS-422 SSI absolute encoders, Siemens type 6FX2001-5, 24 V supply: 125 kHz, 320 meters shielded, max.; 250 kHz, 160 meters shielded, max.; 500 kHz, 60 meters shielded, max.; 1 MHz, 20 meters shielded, max. 1.5 MHz, 10 meters shielded, max.; 2 MHz, 8 meters shielded, max.","Freely usable digital output":"Yes","Pulse Encoder With Direction":"Yes","Pulse encoder with direction":"Yes","Horizontal Installation, Max.":"60 °C; Please note derating for inductive loads","Horizontal Installation, Min.":"-30 °C","Monitoring the supply voltage":"Yes","Telegram error at SSI encoder":"Yes","Signal filter, parameterizable":"Yes","Counting range, parameterizable":"Yes","Digital inputs, parameterizable":"Yes","Hardware gate via digital input":"Yes","Measuring time, parameterizable":"Yes","to standard PROFINET controller":"Yes","Can be changed from user program":"Yes","Counter response parameterizable":"Yes","Cycle duration measurement, max.":"25 s","Cycle duration measurement, min.":"0.25 µs","Digital outputs, parameterizable":"Yes","Telegram length, parameterizable":"10 ... 40 bit","Synchronization via digital input":"Yes","Permissible Voltage At Input, Max.":"30 V","Permissible Voltage At Input, Min.":"-30 V; -5 V continuous, -30 V brief reverse polarity protection","For Signal \"1\" Minimum Load Current":"2 mA","Suitable for S7-1500 Motion Control":"Yes","permissible range, lower limit (DC)":"19.2 V","permissible range, upper limit (DC)":"28.8 V","Dynamic measurement period adjustment":"Yes","For Signal \"0\" Residual Current, Max.":"0.5 mA","Number of thresholds, parameterizable":"2","Between The Channels And Backplane Bus":"Yes","Can be used with TO High_Speed_Counter":"Yes; only for pulse and incremental encoders","For Signal \"1\" Permissible Range, Max.":"0.6 A; Per digital output","PROFIBUS from GSD version/GSD revision":"GSD Revision 5","PROFINET from GSD version/GSD revision":"V2.3 / -","Power available from the backplane bus":"1.3 W","Switching tripped by comparison values":"Yes","Between the channels and load voltage L+":"No","Monitoring of the supply voltage (PWR-LED)":"Yes; green LED","A/B transition error at incremental encoder":"Yes","Installation altitude above sea level, max.":"5 000 m; restrictions for installation altitudes > 2 000 m, see ET 200MP system manual","Limitation of inductive shutdown voltage to":"L+ (-33 V)","Incremental encoder with A/B tracks, 90° phase offset":"Yes","STEP 7 TIA Portal configurable/integrated from version":"V17","Pulse Encoder With One Impulse Signal Per Count Direction":"Yes","Incremental encoder with A/B tracks, 90° phase offset and zero track":"Yes"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$346.71 – $653.31","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/fb24f3d651d5056e750fb0030aff1edf.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1558331&mlfb=6ES7551-1AB01-0AB0"},"ai":{"faq":[],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/6ES7551-1AB01-0AB0","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/6ES7551-1AB01-0AB0 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}