All register readings show NaN or zero. What is wrong?

The SICAM T 7KG966 returns IEEE 754 floats spanning two consecutive holding registers. If your Modbus client byte order is set to little-endian or swapped-word, all float values will decode as NaN or nonsense. Set your client to big-endian (MSB first, high word first) to match the device's native byte order.

The gateway connects but live data never updates. Why?

The SICAM T 7KG966 supports up to a limited number of simultaneous Modbus TCP connections. If another SCADA client or web session already holds all available connections, the ModbusCloud Gateway request will time out. Close other active Modbus TCP sessions or increase the poll interval to reduce connection pressure.

Phase voltage on L2 reads correctly but L1 and L3 look wrong.

Register addresses for voltage_l1 (200), voltage_l2 (202), and voltage_l3 (204) each occupy two registers (float32). Verify the read length in the gateway configuration covers at least 6 registers starting at address 200. A read-length mismatch causes only the first float to decode correctly while the others shift.

Reactive power values appear with the wrong sign for my installation.

The sign of reactive power depends on the direction-of-current parameterization inside the SICAM T 7KG966, which is configurable via the device web interface. Check the current direction setting in the communication or measurement section and adjust to match your wiring convention before trusting reactive power sign in dashboards.

Free Modbus template: Siemens SICAMT7KG966

Name: Siemens SICAMT7KG966
Brand: Siemens
SKU: 39a41286-5996-4684-9ca4-58c062b48ed2

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Free Modbus template: Siemens SICAMT7KG966 | ModbusCloud

Registers (17)

17 read / 0 write

Name	Address	Function	Type	Unit	Access
voltage_l1 Phase L1 to neutral AC voltage, volts.	200	FC03	float32	V	R
voltage_l2 Phase L2 to neutral AC voltage, volts.	202	FC03	float32	V	R
voltage_l3 Phase L3 to neutral AC voltage, volts.	204	FC03	float32	V	R
current_l1 AC current on phase L1, amperes.	208	FC03	float32	A	R
current_l2 AC current on phase L2, amperes.	210	FC03	float32	A	R
current_l3 AC current on phase L3, amperes.	212	FC03	float32	A	R
voltage Mean three-phase AC voltage, volts.	222	FC03	float32	V	R
current Mean three-phase AC current, amperes.	224	FC03	float32	A	R
active_power_l1 Active power on phase L1, watts.	226	FC03	float32	W	R
active_power_l2 Active power on phase L2, watts.	228	FC03	float32	W	R
active_power_l3 Active power on phase L3, watts.	230	FC03	float32	W	R
active_power Total three-phase active power, watts.	232	FC03	float32	W	R
reactive_power_l1 Reactive power on phase L1, volt-amperes reactive.	234	FC03	float32	W	R
reactive_power_l2 Reactive power on phase L2, volt-amperes reactive.	236	FC03	float32	W	R
reactive_power_l3 Reactive power on phase L3, volt-amperes reactive.	238	FC03	float32	W	R
reactive_power Total three-phase reactive power, var.	240	FC03	float32	var	R
frequency AC grid frequency, hertz, typically 50 or 60.	274	FC03	float32	Hz	R