{"product_id":"rs485-modbus-card-mppt-solar-charge-controller-systellar","title":"RS485 \/ Modbus Communication Card for Systellar MPPT Solar Charge Controllers","description":"\u003ch2\u003eAdd Modbus RTU monitoring and control to your Systellar MPPT charge controller\u003c\/h2\u003e\n\u003cp\u003eThe Systellar RS485 \/ Modbus Card is a factory-supported optional interface that lets any external controller, IoT gateway, data logger, PLC, HMI or SCADA system read live data from — and write charging setpoints to — your Systellar MPPT solar charge controller.\u003c\/p\u003e\n\u003cp\u003eThe card communicates using the industry-standard \u003cstrong\u003eModbus RTU\u003c\/strong\u003e protocol over a 2-wire RS485 bus, so it works with virtually any monitoring hardware or software you already use. Supplied with its mating connector, ready to wire in.\u003c\/p\u003e\n\u003ch3\u003eCompatible with\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSystellar \u003cstrong\u003eMPPT-Compact\u003c\/strong\u003e Solar Charge Controllers\u003c\/li\u003e\n\u003cli\u003eSystellar \u003cstrong\u003eMPPT-Gen6\u003c\/strong\u003e Solar Charge Controllers\u003c\/li\u003e\n\u003cli\u003eSystellar \u003cstrong\u003eMPPT-HV-300\u003c\/strong\u003e Solar Charge Controllers\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: this interface requires the charge controller to be supplied with the matching Modbus firmware. Please order this card together with your charge controller, or contact us at info@systellar.in with your controller serial number before ordering separately.\u003c\/em\u003e\u003c\/p\u003e\n\u003ch3\u003eWhat you can read from the controller\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eBattery voltage\u003c\/li\u003e\n\u003cli\u003eBattery current\u003c\/li\u003e\n\u003cli\u003ePV (solar array) voltage\u003c\/li\u003e\n\u003cli\u003ePV (solar array) current\u003c\/li\u003e\n\u003cli\u003eFault and status flags (bit-mapped)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhat you can write to the controller\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eBattery end-of-charge voltage (V_BATT_EOC)\u003c\/li\u003e\n\u003cli\u003eBattery trickle \/ float voltage (V_BATT_TRICKLE)\u003c\/li\u003e\n\u003cli\u003eMaximum charging current (MAX_I_CHG)\u003c\/li\u003e\n\u003cli\u003eAbsorption mode duration, in minutes\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eInterface specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eProtocol\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eModbus RTU\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePhysical layer\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eRS485, 2-wire (2W), half duplex\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eConnections\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e3 wires — GND, D+, D-\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eBaud rate\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e9600 baud\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eFrame format\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e8 data bits, no parity, 1 stop bit (8-N-1)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRole\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eCharge controller LC = Master\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eDefault slave address\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0x01 (changeable from the controller front panel)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eRegister width\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e16-bit u\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eScaling\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eVoltage and current in ×100 units (0–65535 = 0.00 to 655.35 V \/ A)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSupported function codes\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e0x03 Read Holding Registers, 0x04 Read Input Registers, 0x06 Write Single Register\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePower supply to master\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003eNot provided — power your IoT device directly from the battery\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003ch3\u003eRegister map\u003c\/h3\u003e\n\u003cp\u003e\u003cstrong\u003eRead registers (data from the charge controller)\u003c\/strong\u003e\u003c\/p\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eRegister\u003c\/th\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eUnits\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e51\u003c\/td\u003e\n\u003ctd\u003eFaults \/ status flags\u003c\/td\u003e\n\u003ctd\u003eBit-mapped\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e201\u003c\/td\u003e\n\u003ctd\u003eBattery voltage\u003c\/td\u003e\n\u003ctd\u003eVolt ×100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e202\u003c\/td\u003e\n\u003ctd\u003eBattery current\u003c\/td\u003e\n\u003ctd\u003eAmp ×100\u003c\/td\u003e\n\u003ctd\u003e203\u003c\/td\u003e\n\u003ctd\u003ePV voltage\u003c\/td\u003e\n\u003ctd\u003eVolt ×100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e204\u003c\/td\u003e\n\u003ctd\u003ePV current\u003c\/td\u003e\n\u003ctd\u003eAmp ×100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cstrong\u003eWrite registers (setpoints to the charge controller)\u003c\/strong\u003e\u003c\/p\u003e\n\u003ctable\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003cth\u003eRegister\u003c\/th\u003e\n\u003cth\u003eParameter\u003c\/th\u003e\n\u003cth\u003eUnits\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e102\u003c\/td\u003e\n\u003ctd\u003eV_BATT_EOC — battery end-of-charge voltage\u003c\/td\u003e\n\u003ctd\u003eVolt ×100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e103\u003c\/td\u003e\n\u003ctd\u003eV_BATT_TRICKLE — trickle \/ float voltage\u003c\/td\u003e\n\u003ctd\u003eVolt ×100\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e104\u003c\/td\u003e\n\u003ctd\u003eMAX_I_CHG — maximum charging current\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e105\u003c\/td\u003e\n\u003ctd\u003eABSORPTION_MODE_MINUTES — absorption duration\u003c\/td\u003e\n\u003ctd\u003eMinutes\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003eEach of these four registers must be written one at a time using a \u003cem\u003eWrite Single Register (0x06)\u003c\/em\u003e command. The controller charges the battery at MAX_I_CHG until it reaches V_BATT_EOC, holds that voltage for ABSORPTION_MODE_MINUTES, then drops to V_BATT_TRICKLE.\u003c\/p\u003e\n\u003ch3\u003eDocumentation — free download\u003c\/h3\u003e\n\u003cp\u003eDownload the full interface specification and the refer\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0964\/0017\/9495\/files\/Systellar_CC_MPPT_Modbus_interface_details_2026_08_08.pdf?v=1786176769\" rel=\"noopener\" target=\"_blank\"\u003eSystellar CC_MPPT_3xx Modbus Interface Details (DOCX)\u003c\/a\u003e — Systellar-specific register map, command examples and wiring notes\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0964\/0017\/9495\/files\/Modbus_Application_Protocol_V1_1b3.pdf?v=1786176769\" rel=\"noopener\" target=\"_blank\"\u003eModbus Application Protocol V1.1b3 (PDF)\u003c\/a\u003e — official Modbus protocol specification\u003c\/li\u003e\n\u003cli\u003e\n\u003ca href=\"https:\/\/cdn.shopify.com\/s\/files\/1\/0964\/0017\/9495\/files\/Modbus_over_serial_line_V1.pdf?v=1786176768\" rel=\"noopener\" target=\"_blank\"\u003eModbus over Serial Line V1.0 (PDF)\u003c\/a\u003e — official RS485 serial line specification\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eIn the box\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e1 × RS485 \/ Modbus interface card\u003c\/li\u003e\n\u003cli\u003e1 × Mating connector for field wiring\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eTechnical support: \u003ca href=\"mailto:info@systellar.in\"\u003einfo@systellar.in\u003c\/a\u003e\u003c\/p\u003e","brand":"Systellar Innovations","offers":[{"title":"Default Title","offer_id":51803427635495,"sku":"SYS-ACC-RS485-01","price":2999.0,"currency_code":"INR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0964\/0017\/9495\/files\/rs485-modbus-card.jpg?v=1786185951","url":"https:\/\/systellar.myshopify.com\/products\/rs485-modbus-card-mppt-solar-charge-controller-systellar","provider":"Systellar Innovations Online Store","version":"1.0","type":"link"}