Why do voltage and current readings show zero or incorrect values after connecting the meter?

The CT ratio on the meter must be programmed to match the installed current transformers. If the ratio is left at the factory default and does not match your CTs, readings will be wrong. Use the front panel buttons to set the correct ratio.

What parity setting should I use on the gateway?

The OB737-CT supports both None and Even parity. Make sure the parity setting on the ModbusCloud gateway port matches what is configured on the meter. The default is typically None.

Why do I see two sets of energy registers with different values?

The meter exposes energy data at address ranges 352/358 and 2048/2304. These likely represent resettable and cumulative totals. Choose the address range that fits your use case, or read both to compare.

How should I handle the float32 register format?

All registers are float32, each spanning two consecutive 16-bit Modbus registers. The ModbusCloud template already configures the correct data type and register pairing. If you build custom registers, ensure you select float32 and the correct byte order.

Free Modbus template: OB737-CT Energy Meter

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Free Modbus template: OB737-CT Energy Meter | ModbusCloud

Registers (35)

35 read / 0 write

Name	Address	Function	Type	Unit	Access
Voltage L1	16	FC04	float32	V	R
Voltage L2	18	FC04	float32	V	R
Voltage L3	20	FC04	float32	V	R
Frequency	78	FC04	float32	Hz	R
Current L1	80	FC04	float32	A	R
Current L2	82	FC04	float32	A	R
Current L3	84	FC04	float32	A	R
Current Neutral	86	FC04	float32	A	R
Current Total	88	FC04	float32	A	R
Power L1	144	FC04	float32	kW	R
Power L2	146	FC04	float32	kW	R
Power L3	148	FC04	float32	kW	R
Power Total	150	FC04	float32	kW	R
Apparent Power	208	FC04	float32	kVA	R
Apparent Power L2	210	FC04	float32	kVA	R
Apparent Power L3	212	FC04	float32	kVA	R
Apparent Power Total	214	FC04	float32	kVA	R
Reactive Power L1	272	FC04	float32	kvar	R
Reactive Power L2	274	FC04	float32	kvar	R
Reactive Power L3	276	FC04	float32	kvar	R
Reactive Power Total	278	FC04	float32	kvar	R
Power Factor L1	336	FC04	float32		R
Power Factor L2	338	FC04	float32		R
Power Factor L3	340	FC04	float32		R
Power Factor Total	342	FC04	float32		R
Import Active Energy	352	FC04	float32	kWh	R
Import Reactive Energy	354	FC04	float32	kWh	R
Export Active Energy	358	FC04	float32	kWh	R
Export Reactive Energy	360	FC04	float32	kWh	R
Total Energy	1560	FC04	float32	kWh	R
Import Active Energy	2048	FC04	float32	kWh	R
Export Active Energy	2304	FC04	float32	kWh	R
Total Active Energy	1792	FC04	float32	kWh	R
Import Reactive Energy	2560	FC04	float32	Kvarh	R
Export Reactive Energy	2816	FC04	float32	Kvarh	R

OB737-CT Energy Meter

Overview

Key readings

Use cases

Installation

Things to watch for

Registers (35)

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