Modbus RTU
Finder 7M.38
Finder
Three-phase MID energy meter with RS485: voltage, current, power, power factor, THD and the E1 to E4 energy registers over Modbus RTU.
Overview
The Finder 7M.38 is a three-phase MID energy meter for 80 A direct connection, and the 7M.38.8.400.0212 version has an RS485 port with Modbus RTU. This template follows the Finder document Modbus communication protocol 7M24 - 7M38 (v2) and reads the IEEE 754 float values: voltages, currents, active, reactive and apparent power per phase and in total, power factor, frequency, THD per phase, the four non-resettable energy registers E1 to E4 and status registers for phase validity, internal checks and alarm limits. Factory link: address 33, 19200 baud, 8 data bits, no parity, 2 stop bits.
Key readings
- Phase-to-neutral and phase-to-phase voltages
- Current per phase, average and sum
- Active, reactive and apparent power per phase and in total
- Power factor per phase and total, frequency
- THD of voltage and current per phase
- Energy registers E1 to E4 in Wh and varh
- Phase, checksum and alarm status, active tariff
Use cases
- Track Energy Counter E1 per day to report the consumption of a group or tenant.
- Alert when Total Active Power exceeds the capacity of a group or connection.
- Compare Current L1, L2 and L3 to find an unbalanced load in a distribution board.
- Watch THD Voltage and THD Current per phase to spot harmonic problems from drives or chargers.
- Raise a warning when Phase Measurement Status or Checksum Status is not 0.
Installation
- 1Connect terminals A and B of the COM block on the 7M.38.8.400.0212 to the RS485 port of your ModbusCloud Gateway, and SC to the cable shield or signal common. Terminate both ends of the bus.
- 2On the meter, open Settings > Communication and check Device address (factory 33), Bits per second (19200), Parity (none) and Stop bits (2).
- 3In ModbusCloud, add a Modbus device (RTU) with the same address and serial settings, then import this template.
- 4Check the link: Frequency should read about 50 Hz and Voltage L1-N about 230 V.
- 5Read Energy Counter E1 to E4 Parameter to see what each energy register counts before you name them in dashboards.
Things to watch for
- The meter does not answer on the RS485 bus. What should I check?
- Only the 7M.38.8.400.0212 has Modbus RTU; the 0112 has pulse outputs and the 0312 M-Bus. Check the settings under Settings > Communication: factory address 33, 19200 baud and 8N2, so two stop bits and no parity. Then swap A and B and check the termination at both ends of the bus.
- Why do I get an exception or wrong values at register 32500?
- Finder counts from 30000 as the memory reference. The address in the request is the register number minus 30000, so 32500 becomes 2500, read with function code 04. Tools that subtract 30001 read one register too early and return nonsense.
- Which energy register is import and which is export?
- That depends on the configuration. E1 to E4 are set with Energy Counter E1 to E4 Parameter and a quadrant configuration. Read the Parameter registers in this template and compare them with the OBIS or letter code on the display, for example A.I.0 for active import and A.E.0 for active export.
- Why are there no registers with an exponent, like in the T5 format?
- The same measurements exist as T5, T6 and T7 values with the decade exponent inside the top byte. This template reads the IEEE 754 float block from register 32480 instead, which already holds the value in its unit, so no exponent or scale is needed.
- Several meters on one bus answer at random.
- Every meter leaves the factory with address 33. Give each meter its own address under Settings > Communication before you connect them to the same RS485 line.
Registers (53)
53 read / 0 write
| Name | Address | Function | Type | Unit | Access |
|---|---|---|---|---|---|
Voltage L1-N Phase-to-neutral voltage of phase 1 in volts, IEEE 754 float. Finder name: U1, register 32500. | ••• | ••• | ••• | V | R |
Voltage L2-N Phase-to-neutral voltage of phase 2 in volts, IEEE 754 float. Finder name: U2, register 32502. | ••• | ••• | ••• | V | R |
Voltage L3-N Phase-to-neutral voltage of phase 3 in volts, IEEE 754 float. Finder name: U3, register 32504. | ••• | ••• | ••• | V | R |
Voltage L1-L2 Phase-to-phase voltage L1-L2 in volts. Finder name: U12, register 32508. | ••• | ••• | ••• | V | R |
Voltage L2-L3 Phase-to-phase voltage L2-L3 in volts. Finder name: U23, register 32510. | ••• | ••• | ••• | V | R |
Voltage L3-L1 Phase-to-phase voltage L3-L1 in volts. Finder name: U31, register 32512. | ••• | ••• | ••• | V | R |
Current L1 Current in phase 1 in amperes. Finder name: I1, register 32516. | ••• | ••• | ••• | A | R |
Current L2 Current in phase 2 in amperes. Finder name: I2, register 32518. | ••• | ••• | ••• | A | R |
Current L3 Current in phase 3 in amperes. Finder name: I3, register 32520. | ••• | ••• | ••• | A | R |
Total Active Power Total active power of all phases in watts. Finder name: Active Power Total (Pt), register 32536. | ••• | ••• | ••• | W | R |
Active Power L1 Active power of phase 1 in watts. Finder name: Active Power Phase L1 (P1), register 32530. | ••• | ••• | ••• | W | R |
Active Power L2 Active power of phase 2 in watts. Finder name: Active Power Phase L2 (P2), register 32532. | ••• | ••• | ••• | W | R |
Active Power L3 Active power of phase 3 in watts. Finder name: Active Power Phase L3 (P3), register 32534. | ••• | ••• | ••• | W | R |
Frequency Mains frequency in hertz (nominal 50 or 60 Hz). Finder name: Frequency, register 32584. | ••• | ••• | ••• | Hz | R |
Total Reactive Power Total reactive power in var. Finder name: Reactive Power Total (Qt), register 32544. | ••• | ••• | ••• | var | R |
Total Apparent Power Total apparent power in VA. Finder name: Apparent Power Total (St), register 32552. | ••• | ••• | ••• | VA | R |
Total Power Factor Power factor over all phases. Finder name: Power Factor Total (PFt), register 32560. | ••• | ••• | ••• | R | |
Average Voltage L-N Average phase-to-neutral voltage in volts. Finder name: Uavg (phase to neutral), register 32506. | ••• | ••• | ••• | V | R |
Average Voltage L-L Average phase-to-phase voltage in volts. Finder name: Uavg (phase to phase), register 32514. | ••• | ••• | ••• | V | R |
Average Current Average of the three phase currents in amperes. Finder name: Iavg, register 32528. | ••• | ••• | ••• | A | R |
Sum Of Currents Sum of the three phase currents in amperes. Finder name: S I, register 32522. | ••• | ••• | ••• | A | R |
Reactive Power L1 Reactive power of phase 1 in var. Finder name: Reactive Power Phase L1 (Q1), register 32538. | ••• | ••• | ••• | var | R |
Reactive Power L2 Reactive power of phase 2 in var. Finder name: Reactive Power Phase L2 (Q2), register 32540. | ••• | ••• | ••• | var | R |
Reactive Power L3 Reactive power of phase 3 in var. Finder name: Reactive Power Phase L3 (Q3), register 32542. | ••• | ••• | ••• | var | R |
Apparent Power L1 Apparent power of phase 1 in VA. Finder name: Apparent Power Phase L1 (S1), register 32546. | ••• | ••• | ••• | VA | R |
Apparent Power L2 Apparent power of phase 2 in VA. Finder name: Apparent Power Phase L2 (S2), register 32548. | ••• | ••• | ••• | VA | R |
Apparent Power L3 Apparent power of phase 3 in VA. Finder name: Apparent Power Phase L3 (S3), register 32550. | ••• | ••• | ••• | VA | R |
Power Factor L1 Power factor of phase 1. Finder name: Power Factor Phase 1 (PF1), register 32554. | ••• | ••• | ••• | R | |
Power Factor L2 Power factor of phase 2. Finder name: Power Factor Phase 2 (PF2), register 32556. | ••• | ••• | ••• | R | |
Power Factor L3 Power factor of phase 3. Finder name: Power Factor Phase 3 (PF3), register 32558. | ••• | ••• | ••• | R | |
THD Voltage L1 Total harmonic distortion of the voltage in phase 1, in percent. Finder name: U1 THD%, register 32594. | ••• | ••• | ••• | % | R |
THD Voltage L2 Total harmonic distortion of the voltage in phase 2, in percent. Finder name: U2 THD%, register 32596. | ••• | ••• | ••• | % | R |
THD Voltage L3 Total harmonic distortion of the voltage in phase 3, in percent. Finder name: U3 THD%, register 32598. | ••• | ••• | ••• | % | R |
THD Current L1 Total harmonic distortion of the current in phase 1, in percent. Finder name: I1 THD%, register 32588. | ••• | ••• | ••• | % | R |
THD Current L2 Total harmonic distortion of the current in phase 2, in percent. Finder name: I2 THD%, register 32590. | ••• | ••• | ••• | % | R |
THD Current L3 Total harmonic distortion of the current in phase 3, in percent. Finder name: I3 THD%, register 32592. | ••• | ••• | ••• | % | R |
Internal Temperature Temperature inside the meter in °C. Finder name: Internal Temperature, register 32658. | ••• | ••• | ••• | °C | R |
Energy Counter E1 Non-resettable (legally relevant) energy register E1 in Wh as listed by Finder. What it counts is set by Energy Counter E1 Parameter and its quadrant configuration. Finder name: Energy Counter n1, register 32752. | ••• | ••• | ••• | Wh | R |
Energy Counter E2 Non-resettable (legally relevant) energy register E2 in varh as listed by Finder. What it counts is set by Energy Counter E2 Parameter and its quadrant configuration. Finder name: Energy Counter n2, register 32754. | ••• | ••• | ••• | varh | R |
Energy Counter E3 Non-resettable (legally relevant) energy register E3 in Wh as listed by Finder. What it counts is set by Energy Counter E3 Parameter and its quadrant configuration. Finder name: Energy Counter n3, register 32756. | ••• | ••• | ••• | Wh | R |
Energy Counter E4 Non-resettable (legally relevant) energy register E4 in varh as listed by Finder. What it counts is set by Energy Counter E4 Parameter and its quadrant configuration. Finder name: Energy Counter n4, register 32758. | ••• | ••• | ••• | varh | R |
Run Time Operating time of the meter in seconds. Finder name: Run time, register 32480. | ••• | ••• | ••• | s | R |
Phase Measurement Status Bitfield: bit 0 = invalid measurement phase 1, bit 1 = phase 2, bit 2 = phase 3. 0 = all phases valid. Register 30101. | ••• | ••• | ••• | R | |
Checksum Status Bitfield of internal checks. 0 = no error. Bit 0 parameter CRC, bit 1 firmware CRC, bit 2 MID lock, bits 3 to 13 module and data checksums, bit 15 installation not set. Register 30400. | ••• | ••• | ••• | R | |
Alarm Flags Group 1 And 2 Bitfield of the programmable alarm limits: bits 0 to 4 group 1, bits 8 to 12 group 2. 0 = no limit active. Register 30191. | ••• | ••• | ••• | R | |
Alarm Flags Group 3 And 4 Bitfield of the programmable alarm limits: bits 0 to 4 group 3, bits 8 to 12 group 4. 0 = no limit active. Register 30192. | ••• | ••• | ••• | R | |
Current Active Tariff Tariff currently active for the energy counters. Register 30405 (Current Active Tariff). | ••• | ••• | ••• | R | |
Software Reference Firmware version of the meter as a number. Register 30013 (Software Reference). | ••• | ••• | ••• | R | |
Connection Mode Configured wiring: 1 = 1b single phase, 2 = 3b 3-wire balanced, 3 = 4b 4-wire balanced, 4 = 3u 3-wire unbalanced, 5 = 4u 4-wire unbalanced. Read only here. Register 40143. | ••• | ••• | ••• | R | |
Energy Counter E1 Parameter Quantity that energy register E1 integrates (active, reactive or apparent power, total or per phase). Read only here. Register 40421 (Energy Counter n1 Parameter). | ••• | ••• | ••• | R | |
Energy Counter E2 Parameter Quantity that energy register E2 integrates (active, reactive or apparent power, total or per phase). Read only here. Register 40425 (Energy Counter n2 Parameter). | ••• | ••• | ••• | R | |
Energy Counter E3 Parameter Quantity that energy register E3 integrates (active, reactive or apparent power, total or per phase). Read only here. Register 40429 (Energy Counter n3 Parameter). | ••• | ••• | ••• | R | |
Energy Counter E4 Parameter Quantity that energy register E4 integrates (active, reactive or apparent power, total or per phase). Read only here. Register 40433 (Energy Counter n4 Parameter). | ••• | ••• | ••• | R |
Loading registers…
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