{"product_id":"1794-ir8-allen-bradley-flex-i-o-rtd-module-8-channel","title":"1794-IR8 Allen-Bradley FLEX I\/O RTD Module 8 Channel","description":"\u003ch3\u003e\u003cb\u003eTechnical Overview\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong style=\"color: #0056b3;\"\u003e1794-IR8\u003c\/strong\u003e is an 8-channel high-resolution Resistance Temperature Detector (RTD) analog input module belonging to the \u003cstrong style=\"color: #0056b3;\"\u003eAllen-Bradley\u003c\/strong\u003e \u003ca href=\"https:\/\/www.plcsparehub.com\/collections\/allen-bradley-1794-flex-i-o\"\u003eFLEX I\/O\u003c\/a\u003e architecture. Engineered for high-accuracy industrial temperature monitoring, this module digitizes analog signals from various Platinum, Nickel, and Copper RTD elements or direct resistance sources into 16-bit 2's complement or unipolar offset binary formats.\u003c\/p\u003e\n\u003cp\u003eOperating via a 24 VDC external power supply (19.2 to 31.2 VDC range), the \u003cstrong style=\"color: #0056b3;\"\u003e1794-IR8\u003c\/strong\u003e supplies a precise 718.36 μA excitation current across its 1 to 433 Ohm input spectrum. The module features Removal and Insertion Under Power (RIUP) capability, allowing hot-swapping during active system operation without disrupting adjacent rack traffic or backplane communication. Wiring directly to a dedicated FLEX I\/O terminal base eliminates external terminal blocks, reducing cabinet footprint and installation complexity.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eSignal Processing \u0026amp; Performance Architecture\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eHigh-Resolution Analog Conversion\u003c\/b\u003e\n\u003cul\u003e\n\u003cli\u003e16-bit analog-to-digital resolution across a full-scale 435 Ohm measuring range.\u003c\/li\u003e\n\u003cli\u003eSystem accuracy of ±0.05% full scale in Normal Mode and up to ±0.01% full scale in Enhanced Mode (at low humidity without dynamic recalibration).\u003c\/li\u003e\n\u003cli\u003eProgrammable system scan\/throughput rates ranging from 28 ms to 2.6 s for 8 channels in Normal Mode, and up to 2.925 s in High-Precision Enhanced Mode.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eNoise Attenuation \u0026amp; Filter Performance\u003c\/b\u003e\n\u003cul\u003e\n\u003cli\u003eIntegrates an internal A\/D digital filter with a 10 Hz cutoff frequency, yielding a channel bandwidth of 0 to 2.62 Hz (-3 dB).\u003c\/li\u003e\n\u003cli\u003eNormal Mode Noise Rejection (NMRR) of -60 dB @ 60 Hz for effective line frequency ripple suppression.\u003c\/li\u003e\n\u003cli\u003eCommon Mode Noise Rejection (CMRR) of -120 dB @ 60 Hz and -100 dB @ 50 Hz to prevent ground-loop signal corruption.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eSupported Sensors \u0026amp; Signal Ranges\u003c\/b\u003e\n\u003cul\u003e\n\u003cli\u003ePlatinum RTDs: 100 Ω Pt (α=0.00385 Euro, -200 to +870 °C; α=0.003916 US, -200 to +630 °C), 200 Ω Pt, and 500 Ω Pt.\u003c\/li\u003e\n\u003cli\u003eNickel RTDs: 100 Ω, 120 Ω, 200 Ω, and 500 Ω Ni (α=0.00618 \/ 0.00672, -60 to +250 °C).\u003c\/li\u003e\n\u003cli\u003eCopper RTDs: 10 Ω Cu (α=0.00427, -200 to +260 °C).\u003c\/li\u003e\n\u003cli\u003eDirect Resistance: 1 to 433 Ohm range with Cold Junction Compensation (-20 to +100 °C).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eTechnical Specifications\u003c\/b\u003e\u003c\/h3\u003e\n\u003ctable border=\"1\" cellpadding=\"8\" cellspacing=\"0\"\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eCatalog Number\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong style=\"color: #0056b3;\"\u003e1794-IR8\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eManufacturer \/ Brand\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e\n\u003cstrong style=\"color: #0056b3;\"\u003eAllen-Bradley\u003c\/strong\u003e \/ Rockwell Automation\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eProduct Line\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e\n\u003cstrong style=\"color: #0056b3;\"\u003eFLEX I\/O\u003c\/strong\u003e Series\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eInput Type\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e8-Channel RTD \/ Direct Resistance Analog Inputs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eAnalog Resolution\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e16-Bit Signed (2's Complement or Offset Binary)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eNominal Resistance Range\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e1 to 433 Ohms (435 Ohms Full Scale)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eRTD Excitation Current\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e718.36 μA Constant Current\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eConversion Accuracy\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e0.05% Full Scale (Normal) | 0.01% Full Scale (Enhanced)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eSystem Throughput\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e224 ms (Normal Mode) | 56 ms to 650 ms\/channel (Enhanced)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eFlexBus Current Draw\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e20 mA @ 5 VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eExternal Power Input\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e24 VDC Nominal (19.2 to 31.2 VDC Range, 150 mA)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003ePower \/ Thermal Dissipation\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e3.0 W Maximum | 10.2 BTU\/hr @ 31.2 VDC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eIsolation Rating\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e707 VDC for 60s (Inputs \u0026amp; User Power to Logic Side)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eOperating Temperature\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e0°C to +55°C (32°F to 131°F)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cb\u003eOvervoltage Protection\u003c\/b\u003e\u003c\/td\u003e\n\u003ctd\u003e35 VDC \/ 25 VAC Continuous @ 25°C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003e\u003cb\u003eDiagnostic Capabilities \u0026amp; Telemetry\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eSensor Wire Fault Detection:\u003c\/b\u003e Automatic detection of open sensor elements or broken lead wire conditions with status flag updates mapped to controller memory tags.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eOut-of-Range Conditions:\u003c\/b\u003e Hardware flags trigger when measured resistance falls below 1 Ohm or exceeds 433 Ohms, allowing quick identifying of short circuits or degraded sensor heads.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eBackplane Data Quality Monitoring:\u003c\/b\u003e Controller software reads bit-level channel fault status to isolate channel-specific anomalies without taking the entire rack offline.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eTarget Applications \u0026amp; Industrial Deployment\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eLarge Electric Motor \u0026amp; Generator Stator Protection:\u003c\/b\u003e Connects 10 Ohm Copper or 100 Ohm Platinum RTDs embedded in motor windings to track thermal escalation during continuous load cycles.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003ePetrochemical Storage Tank Monitoring:\u003c\/b\u003e Manages multi-point temperature profiles across distillation columns, bulk chemical storage vessels, and heat exchangers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eHVAC \u0026amp; Boiler Plant Management:\u003c\/b\u003e Interfaces multi-channel ambient and fluid sensors directly to ControlLogix or CompactLogix controllers via standard FLEX communication adapters.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eInstallation \u0026amp; Wiring Practices\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eTerminal Base Mounting:\u003c\/b\u003e Install the module onto a compatible 1794 terminal base (such as 1794-TB3, 1794-TB3T, or 1794-TB3TS) before attaching system wiring.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eShielded Wire Termination:\u003c\/b\u003e Ground the shield wire at the terminal base end only to minimize high-frequency electromagnetic interference in low-level analog lines.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eHot-Swap Protocol:\u003c\/b\u003e When performing RIUP replacement, inspect the terminal base keyswitch position to match the RTD module's designated keying configuration (Key Position 3).\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eLogistics, Packaging \u0026amp; Warranty Support\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eShipping Methods:\u003c\/b\u003e Fast global delivery available via express courier partners: FedEx, UPS, and DHL.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eUnit Condition:\u003c\/b\u003e Factory original, brand-new sealed stock supplied with authentic manufacturer serial numbers.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eWarranty Protection:\u003c\/b\u003e Backed by a comprehensive 12-month full-replacement warranty against functional defects.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eEngineering Selection \u0026amp; Procurement Guide\u003c\/b\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cb\u003eMatch Element Alpha Coefficient:\u003c\/b\u003e Verify whether your field Pt100 sensors use the European standard (α=0.00385) or American standard (α=0.003916) prior to module configuration in the software tree.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eLead Resistance Compensation:\u003c\/b\u003e Utilize 3-wire or 4-wire RTD configurations on the terminal base to eliminate measurement errors caused by long field wire runs.\u003c\/li\u003e\n\u003cli\u003e\n\u003cb\u003eThermal Budget Management:\u003c\/b\u003e Ensure control panel cooling holds internal ambient temperatures below 55 °C when running full 3.0 W thermal dissipation across multiple adjacent high-density cards.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cb\u003eFrequently Asked Questions (FAQ)\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp\u003e\u003cb\u003eQ: What causes channel readings to jump to maximum scale during commissioning?\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eA: This typically indicates an open circuit, a disconnected RTD lead wire, or a configuration mismatch in the controller software regarding the selected sensor type.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: How does switching between Normal Mode and Enhanced Mode impact system performance?\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eA: Enhanced Mode increases measurement accuracy from 0.05% to 0.01% full scale, but extends the total update scan rate per channel from 224 ms to up to 650 ms.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Can direct resistance sources like potentiometers be connected to these channels?\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eA: Yes, any linear resistance source falling within the 1 to 433 Ohm range can be read directly by configuring the input mode accordingly.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: Is external 24 VDC power required if the module is connected to a powered FlexBus?\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eA: Yes, the FlexBus only provides 20 mA logic power; the field input circuitry requires external 24 VDC power applied to the terminal base.\u003c\/p\u003e\n\u003cp\u003e\u003cb\u003eQ: What is the correct keyswitch setting on the terminal base unit for this card?\u003c\/b\u003e\u003c\/p\u003e\n\u003cp\u003eA: Turn the terminal base keyswitch to position 3 to prevent accidental insertion of incorrect module types into the base assembly.\u003c\/p\u003e\n\u003ch3\u003e\u003cb\u003eGlobal PLC Spare HUB's Insight\u003c\/b\u003e\u003c\/h3\u003e\n\u003cp\u003eA major municipal wastewater treatment facility experienced frequent false over-temperature trips on its primary effluent pumps. The maintenance crew was using unshielded 2-wire RTD runs connected to older legacy transmitters, which suffered from severe ground-loop interference and signal drift whenever large variable frequency drives (VFDs) ramped up nearby.\u003c\/p\u003e\n\u003cp\u003eOur technical team recommended migrating the field connections to an \u003cstrong style=\"color: #0056b3;\"\u003e1794-IR8\u003c\/strong\u003e RTD input card installed on a local FLEX I\/O rack. By deploying 3-wire 100 Ohm Pt RTDs wired directly into a grounded 1794-TB3T terminal base, the plant leveraged the card's 120 dB common-mode rejection and 16-bit filtering. This upgrade stabilized temperature telemetry across all 8 channels, eliminating false trips and saving the municipality costly emergency call-outs.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":45013908324534,"sku":"1794-IR8","price":112.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0722\/7863\/8774\/files\/1794-IR8.jpg?v=1789025416","url":"https:\/\/www.plcsparehub.com\/products\/1794-ir8-allen-bradley-flex-i-o-rtd-module-8-channel","provider":"Global PLC Spare Hub","version":"1.0","type":"link"}