The gateway connects but register 11028 returns zero or no value.

Confirm the RS485 wiring uses a twisted pair for A and B lines, with GND also connected. A missing GND is a common cause of intermittent or zero reads on the Energy Butler GEN2. Also verify that baud rate is 9600 and framing is RTU, not socket or ASCII mode.

I get a CRC error on every poll. What should I check?

CRC errors on the Energy Butler GEN2 typically indicate a framing mismatch. Ensure your RS485 adapter or TCP bridge is configured for RTU framing, not Modbus TCP or ASCII. Some Waveshare adapters ship with protocol conversion enabled by default, which must be disabled for raw RTU pass-through.

The device has two IP addresses on the network. Can I poll it directly over TCP?

The GEN2 exposes data through an internal RS485 bus, not directly via the TCP stack. You must use an RS485-to-Ethernet adapter connected to the COM port. Direct TCP connection to either of the device's IP addresses typically results in a connection-refused error.

After a firmware update the adapter can no longer reach the device.

M-TEC changed the Modbus TCP port with firmware version 27.52.4.0. If your RS485-to-TCP bridge targets the old port 5743, update it to port 502. The slave ID and RTU framing settings remain unchanged after this firmware update.

Free Modbus template: M-TEC Energy Butler GEN2 (pv)

Name: M-TEC Energy Butler GEN2 (pv)
Brand: M-TEC
SKU: 3320bebf-f612-407a-90f5-128b38a997d6

The M-TEC Energy Butler GEN2 (pv) is a hybrid inverter and battery storage system used in residential and light-commercial solar installations. This template connects to the Energy Butler GEN2 over Modbus RTU via an RS485 serial interface, reading the PV generation power output at holding register 11028. With this single register visible in your ModbusCloud portal, you can track live solar yield, detect production anomalies, and feed data into site-level energy balances. The template is designed for installers who need a lightweight, focused view of PV output without requiring a full system integration.