{"product_id":"8-hv-8-solid-state-relays-for-raspberry-pi-io-back-panel","title":"8 HV and 8 Solid-state Relays for Raspberry Pi I\/O Back Panel","description":"\u003cp\u003eThe \u003cstrong\u003e8 HV and 8 Solid-state Relays Card\u003c\/strong\u003e adds sixteen relays to your Raspberry Pi Back Panel, giving you flexible control over a wide range of loads. It combines four relays rated for 250 VAC\/4A, four relays rated for 48 VAC\/8A, and eight solid state-relays rated for 24 VAC\/DC\/2 A, making it suitable for everything from light automation tasks to fast-power switching. Designed for reliability and ease of use, it is an ideal choice for industrial control, home automation, and custom electronics projects.\u003c\/p\u003e\n\u003cp\u003eSeamlessly integrated with the Raspberry Pi Back Panel, the \u003cstrong\u003e8 HV and 8 Solid-state Relays Card \u003c\/strong\u003esupports Command Line,  MODBUS RTU over RS485, CAN support via CANopen, OpenPLC, and CODESYS.\u003c\/p\u003e\n\u003ch3\u003eFEATURES\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003ePlugs directly into the Raspberry Pi Back Panel - no additional wiring or hardware needed\u003c\/li\u003e\n\u003cli\u003e16 onboard relays:\n\u003cul\u003e\n\u003cli\u003e4 x 250V \/ 4A (high voltage)\u003c\/li\u003e\n\u003cli\u003e4 x 48VAC \/ 8A (high current)\u003c\/li\u003e\n\u003cli\u003e8 x 24VAC\/DC \/ 2A (solid-state)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003eDedicated connectors:\n\u003cul\u003e\n\u003cli\u003eHigh\/medium-power relays routed through\u003cstrong\u003e \u003c\/strong\u003e2×8-pin pluggable connectors\u003c\/li\u003e\n\u003cli\u003eSolid-state relays wired directly to the Back Panel for easy integration\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-end=\"491\" data-start=\"465\"\u003eSeamless compatibility\u003c\/strong\u003e with Raspberry Pi Back Panel and other HOP cards\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLED indicators\u003c\/strong\u003e on all relays\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-end=\"585\" data-start=\"545\"\u003eMix of high- and low-power switching\u003c\/strong\u003e in a single expansion card\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-end=\"639\" data-start=\"617\"\u003eReliable isolation\u003c\/strong\u003e for safe operation across different loads\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-end=\"704\" data-start=\"686\"\u003eCompact design\u003c\/strong\u003e optimized for Back Panel slots\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-end=\"761\" data-start=\"740\"\u003eConvenient wiring\u003c\/strong\u003e with pluggable terminals for higher loads\u003c\/li\u003e\n\u003cli\u003eECCN classification: EAR99\u003c\/li\u003e\n\u003cli\u003eOpen source hardware - schematics available\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eDESCRIPTION\u003c\/h3\u003e\n\u003cp data-end=\"538\" data-start=\"109\"\u003ePart of the \u003cstrong\u003e HOP (Hardware On Panel) \u003c\/strong\u003e family developed by Sequent Microsystems, the \u003cstrong\u003e8 HV and 8 Solid-state Relays Card \u003c\/strong\u003eis designed to integrate seamlessly with the Raspberry Pi Back Panel. Up to eight HOP cards—of any type—can be installed on a single Back Panel, offering maximum flexibility for industrial automation applications. Multiple Back Panels can be connected horizontally to support larger projects.\u003c\/p\u003e\n\u003cp data-end=\"643\" data-start=\"540\"\u003eEight solid-state relays are routed to the Back Panel through the J1 2x20 pin connector and can be accessed on the spring loaded connectors. Loads are limited to 2A and 24VAC or DC.\u003c\/p\u003e\n\u003cp data-end=\"643\" data-start=\"540\"\u003eFour high power relays are routed to J2 8-pin connector and can drive loads of up to 250VAC or 30VDC and 4A.\u003c\/p\u003e\n\u003cp data-end=\"643\" data-start=\"540\"\u003eFour medium power relays are routed to J3 8-pin connector and can drive loads of up to 48VAC or 30VDC and 8A. \u003c\/p\u003e\n\u003cp data-end=\"643\" data-start=\"540\"\u003eAll contacts are N.O.\u003c\/p\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\u003cimg style=\"margin-bottom: 16px; float: none;\" alt=\"16-Channel Relay Card for Raspberry Pi\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/16xRELAYS-LAYOUT_d9966f5b-01ba-40cc-a5f3-4f84d84eb3d7_600x600.jpg?v=1759555233\"\u003e\u003c\/div\u003e\n\u003cp data-end=\"1039\" data-start=\"645\"\u003eLike all HOP cards, the 16-Channel HV-SS Relay Card\u003cspan style=\"font-size: 0.875rem;\"\u003e features 18 LED indicators. The power LED blinks when power is applied and the local processor is operational. An error LED illuminates when the dedicated PANIC pin on the Back Panel terminal block is activated. Sixteen LEDs show the status of the relays.\u003c\/span\u003e\u003c\/p\u003e\n\u003cp data-end=\"1170\" data-start=\"1041\"\u003eAn RS485 port enables communication with external PLCs or industrial controllers using the industry-standard \u003cstrong\u003eMODBUS RTU\u003c\/strong\u003e protocol.\u003c\/p\u003e\n\u003cdiv\u003e\n\u003cp data-end=\"161\" data-start=\"139\"\u003e\u003cstrong\u003ePower Requirements\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-end=\"220\" data-start=\"163\"\u003eThe card is powered via the Back Panel power connector. All the relay coils use 24VDC. The solid-state relays need 2.5 mA each to operate. The medium and high power relays require 15mA each. The local processor is powered from the 5V rail through a 3.3V LDO regulator and consumes 10 mA.\u003cstrong\u003e\u003c\/strong\u003e\u003cstrong\u003e\u003c\/strong\u003e\u003c\/p\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eWATCHDOG:\u003c\/strong\u003e If the watchdog is enabled and the Raspberry Pi fails to access the 16-Channel HV-SS Relay Card within the preset time, the card signals the Back Panel, which performs a hard reset of the Raspberry Pi by turning the power off for 10 seconds.\u003cstrong\u003e\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eSTACK LEVEL: \u003c\/strong\u003eThe stack level is automatically determined by the slot into which the card is inserted on the Back Panel. It is shown on the OLED display after power up. Up to eight cards of the same type can be connected to a single Back Panel installation.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003eINTERRUPT:\u003c\/strong\u003e Any HOP card can be programmed to interrupt the Raspberry Pi. The interrupt handler running on Raspberry Pi needs to monitor pin 37 on the GPIO interface.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003eBACK PANEL TERMINAL BLOCK PINOUT\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv\u003eEach slot on the Back Panel has alocated three 6-pin spring loaded terminal blocks for IO wiring. The pinout is shown in the following picture:\u003c\/div\u003e\n\u003cdiv\u003e\n\u003cstrong\u003e\u003c\/strong\u003e\u003cbr\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\u003cimg alt=\"Raspberry Pi Backpanel Terminal Block IO\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/TerminalBlock-IO_480x480.jpg?v=1759503531\" style=\"margin-bottom: 16px; float: none;\"\u003e\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003eThe \u003cstrong\u003e8 HV and 8 Solid-state Relays Card\u003c\/strong\u003e has the low power relays routed to the Back Panel as follows:\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\n\u003cdiv\u003eIO01-IO02: Relay #1\u003c\/div\u003e\n\u003cdiv\u003eIO03-IO04: Relay #2\u003c\/div\u003e\n\u003cdiv\u003eIO05-IO06: Relay #3\u003c\/div\u003e\n\u003cdiv\u003eIO07-IO08: Relay #4\u003c\/div\u003e\n\u003cdiv\u003eIO09-IO10: Relay #5\u003c\/div\u003e\n\u003cdiv\u003eIO11-IO12: Relay #6\u003c\/div\u003e\n\u003cdiv\u003eIO13-IO14: Relay #7\u003c\/div\u003e\n\u003cdiv\u003eIO15-IO16: Relay #8\u003c\/div\u003e\n\u003cdiv\u003eIO17: ERROR (not used)\u003c\/div\u003e\n\u003cdiv\u003eIO18: PANIC\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eIO17 is an open drain output triggered by a predefined error condition on an out of bounds input. It can be used to activate an external alarm, or can be routed back to IO18 to reset the outputs to a predefined state.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003eIO18 is a dry contact to ground input and can be activated by an external contact wired to the Back Panel terminal block. When triggered, it resets all outputs to a predefined state. \u003c\/div\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003cstrong\u003eDOT MATRIX DISPLAY\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\u003cstrong\u003e\u003cimg alt=\"16-Channel HV-SS Relay OLED\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/8xHV-8xSS-RELAYS-OLED_480x480.jpg?v=1759632557\" style=\"margin-bottom: 16px; float: none;\"\u003e\u003c\/strong\u003e\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003eThe \u003cstrong\u003e8 HV and 8 Solid-state Relays Card\u003c\/strong\u003e includes a 128 × 32 dot-matrix display driven by the on-board processor. It can show status information, self-test results, and error messages. At power up it displays the card name, the I2C address, the slot position and the value of the 24V supply.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003cdiv\u003e\n\u003c!--block--\u003e\u003cstrong\u003eELECTRICAL SPECIFICATIONS\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003c!--block--\u003ePower Supply: 5V 10mA; \u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eSolid-state relays: 8×2.5 mA = \u003cstrong data-start=\"1062\" data-end=\"1071\"\u003e20 mA\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli\u003eMed\/high coils: 8×15 mA = \u003cstrong data-start=\"1102\" data-end=\"1112\"\u003e120 mA\u003c\/strong\u003e\n\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong data-start=\"1117\" data-end=\"1140\"\u003eMax all on ≈ 200 mA\u003c\/strong\u003e (+ logic 10 mA @ 5 V). \u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv\u003e\n\u003c!--block--\u003e\u003cstrong\u003eMECHANICAL SPECIFICATIONS\u003c\/strong\u003e\n\u003c\/div\u003e\n\u003cdiv style=\"text-align: start;\"\u003e\n\u003c!--block--\u003e\u003cspan data-trix-serialize=\"false\" data-trix-cursor-target=\"true\"\u003e\u003c\/span\u003e\n\u003cfigure data-trix-id=\"722\" data-trix-content-type=\"image\" data-trix-attachment='{\"contentType\":\"image\",\"height\":387,\"url\":\"https:\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/ModularIndustrial-Mech.jpg?v=1633452393\",\"width\":600}' class=\"attachment attachment-preview\"\u003e\u003cimg alt=\"16-Channel Relay Card Mechanical\" src=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/mechanical_480x480.jpg?v=1751297156\" style=\"margin-bottom: 16px; float: none;\"\u003e\u003cbr\u003e\n\u003cfigcaption class=\"caption\"\u003e\u003c\/figcaption\u003e\n\u003c\/figure\u003e\n\u003cspan data-trix-serialize=\"false\" data-trix-cursor-target=\"true\"\u003e\u003c\/span\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\n\u003c!--block--\u003e\u003cstrong\u003e \u003c\/strong\u003e\n\u003c\/div\u003e\n\u003ch3\u003e\n\u003c!--block--\u003eDOWNLOADS\u003c\/h3\u003e\n\u003cp\u003eHardware Schematic V1.0\u003c\/p\u003e\n\u003cp\u003e2D DXF Mechanical\u003c\/p\u003e\n\u003cp\u003e3D STEP Model\u003c\/p\u003e\n\u003cp\u003e3D Printable Enclosure\u003c\/p\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch3\u003e\n\u003c!--block--\u003eSOFTWARE\u003c\/h3\u003e\n\u003cdiv\u003e\n\u003cp\u003eCommand Line Drivers\u003c\/p\u003e\n\u003cp\u003ePython Libraries\u003c\/p\u003e\n\u003cp\u003eCODESYS Driver\u003c\/p\u003e\n\u003cp\u003eOpenPLC Module\u003c\/p\u003e\n\u003cbr\u003e\n\u003c\/div\u003e\n\u003cdiv\u003e\u003c!--block--\u003e\u003c\/div\u003e\n\u003cdiv\u003e\u003c!--block--\u003e\u003c\/div\u003e\n\u003ch3\u003e\n\u003c!--block--\u003eQUICK START\u003c\/h3\u003e\n\u003col\u003e\n\u003cli\u003e\n\u003c!--block--\u003ePlug the \u003cstrong\u003e8 HV and 8 Solid-state Relays Card\u003c\/strong\u003e on the Back Panel for Raspberry Pi and power up the system.\u003c\/li\u003e\n\u003cli\u003e\n\u003c!--block--\u003eEnable I2C communication on Raspberry Pi using raspi-config.\u003c\/li\u003e\n\u003cli\u003e\n\u003c!--block--\u003eInstall the software from github.com:\u003c\/li\u003e\n\u003c\/ol\u003e\n\u003cul\u003e\n\u003cli\u003egit clone https:\/\/github.com\/SequentMicrosystems\/sequent-cli.git\u003c\/li\u003e\n\u003cli\u003ecd \/home\/pi\/sequent-cli\u003c\/li\u003e\n\u003cli\u003esudo make install\u003c\/li\u003e\n\u003cli\u003esequent-cli 8ssrel -h\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cdiv\u003e\n\u003c!--block--\u003eThe program will respond with a list of available commands.\u003c\/div\u003e\n\u003cdiv\u003e\u003cbr\u003e\u003c\/div\u003e\n\u003ch3\u003eFAQ\u003c\/h3\u003e\n\u003cp data-end=\"1164\" data-start=\"950\"\u003e\u003cstrong data-end=\"994\" data-start=\"950\"\u003eQ: How is the stack position determined?\u003c\/strong\u003e\u003cbr data-end=\"997\" data-start=\"994\"\u003e\u003cstrong data-end=\"254\" data-start=\"248\"\u003eA:\u003c\/strong\u003e Automatically, by the physical slot on the Back Panel—no DIP switches or software setup needed. The slot is also shown on the OLED at power-up.\u003cbr\u003e\u003c\/p\u003e\n\u003cp data-end=\"1164\" data-start=\"950\"\u003e\u003cstrong data-end=\"504\" data-start=\"438\"\u003eQ: Which relays go to the Back Panel vs. pluggable connectors?\u003c\/strong\u003e\u003cbr data-end=\"507\" data-start=\"504\"\u003e\u003cstrong data-end=\"513\" data-start=\"507\"\u003eA:\u003c\/strong\u003e The eight \u003cstrong data-end=\"555\" data-start=\"524\"\u003esolid-state relays (24 V\/2 A)\u003c\/strong\u003e route to the Back Panel spring terminals via the J1 2×20; the \u003cstrong data-end=\"636\" data-start=\"618\"\u003efour 250 V\/4 A\u003c\/strong\u003e relays go to \u003cstrong data-end=\"662\" data-start=\"650\"\u003eJ2 (2×8)\u003c\/strong\u003e, and the \u003cstrong data-end=\"689\" data-start=\"672\"\u003efour 48 V\/8 A\u003c\/strong\u003e relays go to \u003cstrong data-end=\"715\" data-start=\"703\"\u003eJ3 (2×8)\u003c\/strong\u003e. All contacts are \u003cstrong data-end=\"742\" data-start=\"734\"\u003eN.O.\u003c\/strong\u003e\u003c\/p\u003e\n\u003cp data-end=\"1457\" data-start=\"1166\"\u003e\u003cstrong data-end=\"1206\" data-start=\"1166\"\u003e\u003cstrong data-end=\"835\" data-start=\"782\"\u003eQ: Can I control the card without a Raspberry Pi?\u003c\/strong\u003e\u003cbr data-end=\"838\" data-start=\"835\"\u003e\u003cstrong data-end=\"844\" data-start=\"838\"\u003eA:\u003c\/strong\u003e\u003c\/strong\u003e Yes. Over RS485, the card acts as a MODBUS RTU slave and can be driven by any MODBUS-compatible PLC\/controller.\u003c\/p\u003e\n\u003cp data-end=\"2216\" data-start=\"1989\"\u003e\u003cstrong\u003eQ: How is RS485 wired and managed?\u003c\/strong\u003e\u003cstrong data-end=\"2040\" data-start=\"1989\"\u003e\u003cbr data-end=\"1045\" data-start=\"1042\"\u003e\u003cstrong data-end=\"1051\" data-start=\"1045\"\u003eA:\u003c\/strong\u003e \u003c\/strong\u003eThe RS485 port is permanently tied into the Back Panel’s shared RS485 bus and handled by the on-board processor for MODBUS RTU communication.\u003c\/p\u003e\n\u003cp data-end=\"2602\" data-start=\"2432\"\u003e\u003cstrong data-end=\"2292\" data-start=\"2218\"\u003e\u003cstrong data-end=\"1537\" data-start=\"1491\"\u003eQ: What happens if the Raspberry Pi hangs?\u003c\/strong\u003e\u003cbr data-end=\"1540\" data-start=\"1537\"\u003e\u003cstrong data-end=\"1546\" data-start=\"1540\"\u003eA:\u003c\/strong\u003e \u003c\/strong\u003eWith \u003cstrong\u003eWatchdog \u003c\/strong\u003eenabled, the card signals the Back Panel to hard-reset the Pi (power off ~10 s) if the Pi stops responding in time.\u003c\/p\u003e\n\u003cp data-end=\"2602\" data-start=\"2432\"\u003e\u003cstrong data-end=\"1948\" data-start=\"1916\"\u003eQ: How many cards can I use?\u003c\/strong\u003e\u003cbr data-end=\"1951\" data-start=\"1948\"\u003e\u003cstrong data-end=\"1957\" data-start=\"1951\"\u003eA:\u003c\/strong\u003e Up to \u003cstrong data-end=\"1983\" data-start=\"1964\"\u003eeight HOP cards\u003c\/strong\u003e (any mix) per Back Panel; multiple Back Panels can be chained horizontally for larger systems.\u003c\/p\u003e\n\u003cp data-end=\"2602\" data-start=\"2432\"\u003e\u003cstrong data-end=\"2422\" data-start=\"2346\"\u003eQ: Any best practices for switching inductive loads (motors, solenoids)?\u003c\/strong\u003e\u003cbr data-end=\"2425\" data-start=\"2422\"\u003e\u003cstrong data-end=\"2431\" data-start=\"2425\"\u003eA:\u003c\/strong\u003e Use proper \u003cstrong data-end=\"2455\" data-start=\"2443\"\u003esnubbers\u003c\/strong\u003e (RC for AC, flyback\/suppressors for DC) and \u003cstrong data-end=\"2519\" data-start=\"2500\"\u003eexternal fusing\u003c\/strong\u003e appropriate to the load to reduce arcing and extend relay life. (General guidance; choose values per your load.)\u003c\/p\u003e\n\u003cp data-end=\"3424\" data-start=\"3173\"\u003e\u003cstrong data-end=\"3224\" data-start=\"3173\"\u003eQ: Where can I find documentation and examples?\u003c\/strong\u003e\u003cbr data-end=\"3227\" data-start=\"3224\"\u003eA: Visit Sequent Microsystems’ GitHub repository for open-source code, wiring diagrams, and setup instructions:\u003cbr data-end=\"3341\" data-start=\"3338\"\u003e👉 \u003ca href=\"https:\/\/github.com\/SequentMicrosystems\" rel=\"noopener\" class=\"\" data-end=\"3424\" data-start=\"3344\"\u003ehttps:\/\/github.com\/SequentMicrosystems\u003c\/a\u003e\u003c\/p\u003e\n\u003cdiv\u003e\u003c!--block--\u003e\u003c\/div\u003e","brand":"Sequent Microsystems","offers":[{"title":"Default Title","offer_id":48181203599612,"sku":"SM-P-111","price":95.0,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0534\/4392\/0067\/files\/8xHV-8xSS-REL-2.jpg?v=1774193050","url":"https:\/\/sequentmicrosystems.com\/products\/8-hv-8-solid-state-relays-for-raspberry-pi-io-back-panel","provider":"Sequent Microsystems","version":"1.0","type":"link"}