{"product_id":"allen-bradley-1794-ir8-flex-i-o-rtd-input-module","title":"Allen-Bradley 1794-IR8 FLEX I\/O RTD Input Module","description":"\u003ch3\u003eDescription\u003c\/h3\u003e\n\u003cp\u003eThe \u003cstrong\u003e1794-IR8\u003c\/strong\u003e is a high-density resistance temperature detector (\u003cstrong\u003eRTD\u003c\/strong\u003e) input module serving as an integrated component within the \u003cstrong\u003eFLEX I\/O\u003c\/strong\u003e distributed network terminal matrix. This field-side hardware solution interfaces directly with diverse temperature elements to capture highly accurate thermal variations, executing precise analog-to-digital data conversions across an isolated backplane. By shifting conversion processes directly to remote processing junctions on standard DIN rails, the device reduces complex analog cable lengths back to central processing nodes, transmitting values over communication adapters including \u003cstrong\u003eEtherNet\/IP\u003c\/strong\u003e, \u003cstrong\u003eControlNet\u003c\/strong\u003e, and \u003cstrong\u003eDeviceNet\u003c\/strong\u003e.\u003c\/p\u003e\n\u003cp\u003eThis industrial unit features eight non-isolated input channels configured to process two-wire, three-wire, or four-wire RTD sensors, as well as pure resistance sensor signals. The \u003cstrong\u003e1794-IR8\u003c\/strong\u003e plugs directly into a standard compatible terminal base unit, drawing operational power and establishing bus backplane lines automatically upon connection. This assembly is standard across petrochemical refining facilities, plastic extrusion plants, power grid sub-stations, and commercial cold-storage installations requiring continuous multi-point ambient and medium thermal monitoring.\u003c\/p\u003e\n\u003ch3\u003eFeatures\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eEight channels for flexible scaling of thermal instrumentation.\u003c\/li\u003e\n\u003cli\u003eNative compatibility with diverse platinum, nickel, and copper RTD types alongside pure ohmic sensor paths.\u003c\/li\u003e\n\u003cli\u003eSelectable digital filtering settings minimizing high-frequency electrical background noise.\u003c\/li\u003e\n\u003cli\u003eLive insertion capability supporting hardware swaps without interrupting communication to adjacent rail components.\u003c\/li\u003e\n\u003cli\u003eDirect register mapping via the FlexBus backplane configuration for seamless integration into the host database.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eApplications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eMulti-point motor bearing temperature protection networks.\u003c\/li\u003e\n\u003cli\u003ePetrochemical vessel and jacketed chemical reactor temperature tracking.\u003c\/li\u003e\n\u003cli\u003eFood processing pasteurization line monitoring.\u003c\/li\u003e\n\u003cli\u003eHVAC air-handler heat-exchanger efficiency verification loops.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eParameter\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eSpecification\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eManufacturer\u003c\/td\u003e\n\u003ctd\u003eRockwell Automation \/ Allen-Bradley\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eFLEX I\/O\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePart Number\u003c\/td\u003e\n\u003ctd\u003e1794-IR8\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eModule Type\u003c\/td\u003e\n\u003ctd\u003eRTD Input Module\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eNumber of Inputs\u003c\/td\u003e\n\u003ctd\u003e8 Channels, Non-Isolated\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSupported Sensor Types\u003c\/td\u003e\n\u003ctd\u003e100, 200, 500, 1000 ohm Platinum; 120 ohm Nickel; 10 ohm Copper; 0 to 433 ohm Resistance\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eResolution\u003c\/td\u003e\n\u003ctd\u003e16-bit across full range\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAccuracy\u003c\/td\u003e\n\u003ctd\u003e0.1% of full scale\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eFlexBus Current Draw\u003c\/td\u003e\n\u003ctd\u003e20 mA at 5V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eExternal Power Supply\u003c\/td\u003e\n\u003ctd\u003e24V DC nominal\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperational Voltage Range\u003c\/td\u003e\n\u003ctd\u003e10V DC to 31.2V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Dissipation\u003c\/td\u003e\n\u003ctd\u003e5.5 W maximum at 31.2V DC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temperature\u003c\/td\u003e\n\u003ctd\u003e0 to 55 degC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eStorage Temperature\u003c\/td\u003e\n\u003ctd\u003e-40 to 85 degC\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eRelative Humidity\u003c\/td\u003e\n\u003ctd\u003e5% to 95% non-condensing\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eCountry of Origin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApproximate Weight\u003c\/td\u003e\n\u003ctd\u003e0.09 kg\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eApproximate Dimensions\u003c\/td\u003e\n\u003ctd\u003e46 mm x 94 mm x 53 mm\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eConnections\/Interfaces\u003c\/h3\u003e\n\u003cfigure class=\"table\"\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003e\u003cstrong\u003eTerminal Block Connection (Typical 1794-TB3G)\u003c\/strong\u003e\u003c\/th\u003e\n\u003cth\u003e\u003cstrong\u003eFunction\u003c\/strong\u003e\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eL(+) \/ L(-)\u003c\/td\u003e\n\u003ctd\u003eExt. Power Supply 24V DC Input \/ Return Nodes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChannel 0 to Channel 7 Source\u003c\/td\u003e\n\u003ctd\u003eCurrent Excitation Source Terminals for RTD Sensors\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChannel 0 to Channel 7 Sense (+)\u003c\/td\u003e\n\u003ctd\u003ePositive Differential Voltage Input Pins\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChannel 0 to Channel 7 Return (-)\u003c\/td\u003e\n\u003ctd\u003eNegative Common Return Reference Connections\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/figure\u003e\n\u003ch3\u003eInstallation Guidelines\u003c\/h3\u003e\n\u003ch3\u003eDIN Rail Installation\u003c\/h3\u003e\n\u003cp\u003eHook the top groove of the module enclosure under the upper lip of standard 35 mm DIN tracking. Apply continuous firm downward pressure on the lower half of the housing until the integrated spring-loaded retention tab snaps shut behind the bottom tracking bar.\u003c\/p\u003e\n\u003ch3\u003eTerminal Base Seating\u003c\/h3\u003e\n\u003cp\u003eAlign the dual guide tracks of the electronic module with the matching alignment grooves on the pre-wired terminal base unit. Slide the device flush into the base socket matrix until the top and bottom latch bars snap outward into their locked configurations.\u003c\/p\u003e\n\u003ch3\u003eShielding and Grounding\u003c\/h3\u003e\n\u003cp\u003eRun all RTD sensor circuits utilizing individual high-quality shielded twisted-pair cables. Terminate the overall copper braided shield drain wire explicitly at the dedicated functional chassis ground points built into the terminal base assembly.\u003c\/p\u003e\n\u003ch3\u003eSensor Cable Length Constraints\u003c\/h3\u003e\n\u003cp\u003eKeep three-wire and four-wire sensor cable runs within official resistance tolerances to prevent adding lead-wire impedance offset values to the internal temperature computation register matrix.\u003c\/p\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the core function of this module assembly?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eIt provides an automated tracking interface that reads analog resistance values from RTD sensors and translates them into digital registers.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan this unit handle two-wire and three-wire RTD sensors simultaneously?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, each channel can be wired independently to match two-wire, three-wire, or four-wire probe layouts based on terminal configurations.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eAre the individual instrumentation channels isolated from each other?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eNo, the eight measurement channels share a common internal reference within the conversion circuitry, though they are isolated from the main control bus.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow does the module deal with an open sensor wire fault?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe module sets an over-range status flag register for the damaged channel and outputs a specific value to indicate a broken sensor circuit.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eIs it safe to pull this module off the rail while the main PLC is running?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, it features removal and insertion under power capabilities, which allows engineers to perform field hot-swaps safely without disabling the network.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat terminal base units are compatible with this device?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe module is commonly paired with the 1794-TB3G, 1794-TB3GS, or 1794-TB32 terminal base units to manage the RTD signal wiring paths.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eDoes this device require a separate external power connection?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, a nominal 24V DC external power source must be run to the terminal base block to power the internal sensor excitation and conversion matrices.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCan this device read raw ohm values instead of temperature parameters?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eYes, the channels can be software-configured to work in a pure resistance mode, measuring raw ohm values up to 433 ohms.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eHow is the sensor selection configured inside the system?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe target sensor material profile and wire configuration are designated by setting configuration parameters in the controller programming environment.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eWhat is the digital conversion resolution of the measurement data?\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp\u003eThe internal analog-to-digital converters process inputs using a precise 16-bit resolution matrix to deliver accurate temperature steps.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":52695177560427,"sku":"1794-IR8","price":100.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0953\/3227\/0443\/files\/allen-bradley-1794-ir8-rtd-input-module-2iiprumqonj_9d58e341-e35e-4249-aa59-6399178686ea.jpg?v=1766114168","url":"https:\/\/www.plcprotech.com\/products\/allen-bradley-1794-ir8-flex-i-o-rtd-input-module","provider":"PLC ProTech Ltd.","version":"1.0","type":"link"}