Siemens 7KT1665 (charge)
The Siemens 7KT1665 is a three-phase SENTRON PAC1600 energy meter rated for direct connection up to 80 A, designed for DIN-rail installation in low-voltage distribution boards. This ModbusCloud template targets the charge-point sub-metering role, reading total active power and cumulative energy import via Modbus RTU over RS-485, plus per-phase currents on L1, L2, and L3. Connecting this meter to a ModbusCloud Gateway lets installers track EV charging loads, verify phase balance, and detect overcurrent conditions in real time without additional hardware.
- Protocol
- Modbus RTU
- Connection
- RS485
- Registers
- 5, read only
- Brand
- Siemens
- Last updated
Registers (5)
5 read, 0 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| power | W | Read | |||
| energy | Read | ||||
| currents_a | A | Read | |||
| currents_b | A | Read | |||
| currents_c | A | Read |
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Use cases
- Monitor total active power at an EV charging point to verify load stays within circuit breaker limits.
- Track cumulative energy import per charging session to generate accurate cost-allocation reports.
- Compare L1, L2, and L3 currents to detect phase imbalance in three-phase wallbox installations.
- Alert on sustained high current on any single phase to identify wiring or load-distribution faults.
- Report monthly energy consumption per charge point to support tenant or fleet billing workflows.
Installation
Enable Modbus RTU on the 7KT1665 by navigating to the communication parameters menu (P07 section) on the front panel and setting the slave address, baud rate, and data format to match your RS-485 network.
Wire the 7KT1665 RS-485 terminals (A/B) to the ModbusCloud Gateway RS-485 port using shielded twisted-pair cable, observing correct polarity and adding a 120-ohm termination resistor at each end of the bus.
In the ModbusCloud portal, add a new gateway, import the Siemens 7KT1665 (charge) template, and assign the Modbus unit ID that matches the slave address configured on the device.
Verify the connection by checking the live readings for power and currents_a in the portal; values should update within a few seconds of applying load at the charge point.
Things to watch for
Why do power or current registers return zero or no response?
Confirm the Modbus slave address on the meter matches the unit ID set in the portal. Also verify baud rate and parity settings under the meter's P07 communication menu. A mismatch in any one parameter causes the device to ignore all requests silently.
Current readings look correct but power reads garbage values. Why?
The power register at address 57 uses a signed INT32 spanning two consecutive 16-bit holding registers. If your gateway reads only one register word, or swaps byte order, the value will be incorrect. Ensure the ModbusCloud Gateway is set to read 2 registers in big-endian (Modbus standard) byte order for INT32 fields.
The meter is on the RS-485 bus but the gateway cannot see it at all.
Check physical wiring: RS-485 requires A and B lines connected without reversal and a 120-ohm termination resistor at both bus ends. The 7KT1665 is self-powered from the measured voltage, so also confirm the mains supply to the meter is live before troubleshooting further.
Energy counter value seems to wrap or reset unexpectedly. What causes this?
The energy register is a UINT32, which rolls over at 4,294,967,295. For high-consumption charge points running over many years, plan for rollover handling in your portal dashboards. Also note that manually resetting energy values on the device front panel will cause a discontinuity in the cloud historical data.
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