{"product_id":"allen-bradley-1746-a4-slc-500-i-o-chassis","title":"Allen-Bradley 1746-A4 SLC 500 I\/O Chassis","description":"\u003ch1\u003eAllen-Bradley 1746-A4 SLC 500 I\/O Chassis\u003c\/h1\u003e\n\u003cp\u003eConfigured for mechanical module housing and SLC 500 backplane power and signal routing, the\u003cspan\u003e \u003c\/span\u003e\u003cstrong\u003eAllen-Bradley 1746-A4\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003e(\u003cstrong\u003e1746-A4\u003c\/strong\u003e\u003cspan\u003e \u003c\/span\u003ePLC chassis) provides direct physical\/electrical execution for slot-based installation of input, output, and communication modules within SLC 500 controller architectures.\u003c\/p\u003e\n\u003cp\u003eThe chassis implements a shared backplane distribution structure supporting 5 VDC logic and 24 VDC field power rails, enabling deterministic module addressing and scan synchronization across a 4-slot architecture.\u003c\/p\u003e\n\u003ch3\u003eHardware Specifications\u003c\/h3\u003e\n\u003ctable class=\"w-fit min-w-(--thread-content-width)\"\u003e\n\u003cthead\u003e\n\u003ctr class=\"firstRow\"\u003e\n\u003cth class=\"last:pe-10\"\u003eParameter\u003c\/th\u003e\n\u003cth class=\"last:pe-10\"\u003eSpecification\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eModel\u003c\/td\u003e\n\u003ctd\u003e1746-A4\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eBrand\u003c\/td\u003e\n\u003ctd\u003eAllen-Bradley\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOrigin\u003c\/td\u003e\n\u003ctd\u003eUSA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eWeight\u003c\/td\u003e\n\u003ctd\u003e1.54 lbs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eDimensions\u003c\/td\u003e\n\u003ctd\u003eApprox. 216 mm width\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eOperating Temp\u003c\/td\u003e\n\u003ctd\u003e0 to 60 deg C\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePower Consumption\u003c\/td\u003e\n\u003ctd\u003eBackplane: 5 VDC 5 A max \/ 24 VDC 1.6 A max\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eSlots\u003c\/td\u003e\n\u003ctd\u003e4 module slots\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eMounting\u003c\/td\u003e\n\u003ctd\u003ePanel or rack mount\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChassis Type\u003c\/td\u003e\n\u003ctd\u003eSLC 500 I\/O chassis\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eSLC 500 Backplane Bus Architecture\u003c\/h3\u003e\n\u003cp\u003eThe 1746-A4 chassis uses a fixed backplane bus structure for module power distribution and communication alignment. Each slot position is electrically indexed to support deterministic module recognition by SLC 500 processors.\u003c\/p\u003e\n\u003cp\u003eThe 5 VDC logic rail distributes control power to installed modules, while the 24 VDC rail supports field-side interfacing loads. Total backplane loading must remain within specified current limits to avoid bus voltage collapse under full module population.\u003c\/p\u003e\n\u003ch3\u003eFrequently Asked Questions (FAQ)\u003c\/h3\u003e\n\u003cp\u003eQ: Can the 1746-A4 operate with partially populated slots?\u003cbr\u003eA: Yes. Unused slots remain electrically inactive but preserve backplane continuity for addressing and scan sequence alignment.\u003c\/p\u003e\n\u003cp\u003eQ: What happens if backplane current limits are exceeded?\u003cbr\u003eA: Exceeding 5 VDC or 24 VDC limits may result in voltage drop across the backplane, causing module resets or communication failure.\u003c\/p\u003e\n\u003cp\u003eQ: Is the chassis hot-swappable during operation?\u003cbr\u003eA: Chassis-level replacement is not intended during operation. Module-level insertion depends on system configuration and installed module electrical isolation design.\u003c\/p\u003e\n\u003chr\u003e\n\u003ch3\u003eField Installation Guidelines\u003c\/h3\u003e\n\u003cp\u003eMount the chassis on a grounded metallic panel using designated mounting points. Ensure full surface contact to maintain mechanical rigidity and stable backplane connector engagement across all slots.\u003c\/p\u003e\n\u003cp\u003eMaintain separation between backplane interconnect wiring and high-noise power conductors. Use shielded routing for communication modules where installed adjacent to switching loads.\u003c\/p\u003e\n\u003cp\u003eVerify protective earth continuity before module insertion. Align modules precisely with slot guides to avoid backplane pin deformation during installation.\u003c\/p\u003e","brand":"Allen-Bradley","offers":[{"title":"Default Title","offer_id":43497784311898,"sku":"1746-A4","price":123.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0612\/4601\/3530\/files\/1746-A42.jpg?v=1781509485","url":"https:\/\/www.plcmasters.com\/products\/allen-bradley-1746-a4-slc-500-i-o-chassis","provider":"PLC Masters Ltd.","version":"1.0","type":"link"}