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RS485 / Modbus Communication Card for Systellar MPPT Solar Charge Controllers
Rs. 2,999.00
Sale price
Rs. 2,999.00
Regular price
Add Modbus RTU monitoring and control to your Systellar MPPT charge controller
The 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.
The card communicates using the industry-standard Modbus RTU 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.
Compatible with
- Systellar MPPT-Compact Solar Charge Controllers
- Systellar MPPT-Gen6 Solar Charge Controllers
- Systellar MPPT-HV-300 Solar Charge Controllers
Note: 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.
What you can read from the controller
- Battery voltage
- Battery current
- PV (solar array) voltage
- PV (solar array) current
- Fault and status flags (bit-mapped)
What you can write to the controller
- Battery end-of-charge voltage (V_BATT_EOC)
- Battery trickle / float voltage (V_BATT_TRICKLE)
- Maximum charging current (MAX_I_CHG)
- Absorption mode duration, in minutes
Interface specifications
| Protocol | Modbus RTU |
| Physical layer | RS485, 2-wire (2W), half duplex |
| Connections | 3 wires — GND, D+, D- |
| Baud rate | 9600 baud |
| Frame format | 8 data bits, no parity, 1 stop bit (8-N-1) |
| Role | Charge controller LC = Master |
| Default slave address | 0x01 (changeable from the controller front panel) |
| Register width | 16-bit u |
| Scaling | Voltage and current in ×100 units (0–65535 = 0.00 to 655.35 V / A) |
| Supported function codes | 0x03 Read Holding Registers, 0x04 Read Input Registers, 0x06 Write Single Register |
| Power supply to master | Not provided — power your IoT device directly from the battery |
Register map
Read registers (data from the charge controller)
| Register | Parameter | Units | |||
|---|---|---|---|---|---|
| 51 | Faults / status flags | Bit-mapped | |||
| 201 | Battery voltage | Volt ×100 | |||
| 202 | Battery current | Amp ×100 | 203 | PV voltage | Volt ×100 |
| 204 | PV current | Amp ×100 |
Write registers (setpoints to the charge controller)
| Register | Parameter | Units |
|---|---|---|
| 102 | V_BATT_EOC — battery end-of-charge voltage | Volt ×100 |
| 103 | V_BATT_TRICKLE — trickle / float voltage | Volt ×100 |
| 104 | MAX_I_CHG — maximum charging current | |
| 105 | ABSORPTION_MODE_MINUTES — absorption duration | Minutes |
Each of these four registers must be written one at a time using a Write Single Register (0x06) 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.
Documentation — free download
Download the full interface specification and the refer
- Systellar CC_MPPT_3xx Modbus Interface Details (DOCX) — Systellar-specific register map, command examples and wiring notes
- Modbus Application Protocol V1.1b3 (PDF) — official Modbus protocol specification
- Modbus over Serial Line V1.0 (PDF) — official RS485 serial line specification
In the box
- 1 × RS485 / Modbus interface card
- 1 × Mating connector for field wiring
Technical support: info@systellar.in