ABB A44 112-100

Power and energy meter

A44 112-100 (2CMA100248R1000) is the Steel-functionality, RS-485 version of ABB’s transformer-connected A44. It suits active-import energy monitoring where external current transformers, and optionally voltage transformers, are required. It is a seven-module DIN meter, rather than the direct-connected A43. Higher A44 tiers add functions that this entry does not claim.

ABB A44 112-100
  • Modbus RTU

Power and energy meter

Compatibility

Compatible through Modbus RTU

Manufacturer-documented serial read path; not physical device validation or a built-in mapping.

Exact A44 112-100, order 2CMA100248R1000. This guide uses revision E of the A43/A44 manual and the Steel feature boundary. Record installed firmware and verify supported quantities. No minimum firmware has been established. The worked read is documented and independently decoded, not a physical Edge qualification. No import template is supplied because unsupported quantities return finite sentinel values requiring explicit rejection.

Connect it with

For the exact RS-485 order code described here

  • Modbus
  • Wireless
  • Edge
  • Platforms
Power and energy meter
Interface
Gateway
Edge
Output
A44 112-100ABB A44 112-100 RS-485 port
ZMB-31Modbus RTU to the EpiSensor wireless network
ZGW-20 GatewayHosts Edge locally
EpiSensor EdgeEdge Modbus client
Customer platformMQTT · API · files
Modbus RTU · RS-485
EpiSensor wireless
Runs locally
Optional onward data
Match the configured serial address, speed, parity and stop bits. Use one master and the manufacturer’s bus wiring and termination. The customer-platform output is optional; Edge remains the local system of record.

Models

Download
ModelsInterfaceRoute into Edge
A44 112-100 / 2CMA100248R1000RS-485, Steel functionality, transformer-connected inputsModbus RTU; select Modbus rather than EQ-Bus in the communication settings.
A44 113-100M-Bus version of the Steel meterNot the RS-485 hardware described here.
A44 Bronze, Silver, Gold and PlatinumDifferent energy, tariff, history and analysis capabilitiesDo not copy their function list merely because the family register map contains those addresses.
A43Direct-connected current inputDifferent electrical installation; this guide concerns external-transformer A44 hardware.

Specifications

The useful distinction is both electrical and functional: A44 uses external transformers, while the 112-100 order selects Steel active-import metering and RS-485. The common manual also covers richer models, so register presence alone does not establish a function on this meter.12

Exact model
A44 112-100, 2CMA100248R1000; Steel, class B / class 1 active energy.2
Current input
Transformer connected; reference current 1 A, maximum secondary current 6 A. Configure the actual primary and secondary CT values.1
Voltage input
3 × 57.7/100 to 288/500 VAC for this standard version; the 690 V A44 variants have different order codes.2
Functions
Active-import energy, instrumentation and pulse/alarm output; not the higher-tier tariff, export-energy or load-profile package.1
Mounting
Seven DIN modules; indoor installation. IP20 terminals without protective enclosure, IP51 in protective enclosure.1
Environmental envelope
Operating −40 to +70 °C; humidity limits and protective enclosure requirements remain applicable.1
Serial settings
Modbus address 1–247; 1200–115200 bit/s choices; none, odd or even parity. Match the actual installed settings.1

Interface

Documented measurements and integration boundaries for A44 112-100.

  • L1-N voltage at literal 0x5B00: two unsigned registers, 0.1 V resolution.
  • Active import energy at 0x5000: four unsigned registers, 0.01 kWh resolution; stored energy already includes the configured transformer ratios.
  • Phase current and active power are available as instrumentation; use the table’s individual sign, width and resolution.
  • Steel provides active-import energy. Export, reactive-energy totals, tariffs, load profiles and harmonic features in other tiers are not promised here.
  • Unavailable unsigned quantities return FFFF in every register; unavailable signed quantities use the maximum positive code for their width.

Assessment

Exact A44 112-100, order 2CMA100248R1000. This guide uses revision E of the A43/A44 manual and the Steel feature boundary. Record installed firmware and verify supported quantities. No minimum firmware has been established. The worked read is documented and independently decoded, not a physical Edge qualification. No import template is supplied because unsupported quantities return finite sentinel values requiring explicit rejection.

InteroperabilityWell supported
An explicit FC03 request, literal register convention, type table and multi-register ordering establish the local read interface.1
AccuracySupported with conditions
The exact Steel order offers class B / class 1 active energy; external CT/VT selection and ratio configuration affect the result.12
SecurityNot yet assessed
No authenticated or encrypted Modbus transport has been demonstrated for this exact order code.1
ReliabilitySupported with conditions
Primary energy storage and invalid-value encodings are documented; reject missing values rather than record them as valid readings.1
RuggednessSupported with conditions
Indoor DIN mounting, enclosure-dependent ingress protection and a stated temperature envelope are documented.1
ScalabilitySupported with conditions
Unique addresses and a documented RS-485 line topology support multiple meters; capacity still depends on wiring and polling schedule.1
LifecycleNot yet assessed
The retained manual and ordering evidence do not establish a current support or firmware-maintenance commitment.12

Setup

Verify L1-N voltage with ABB’s documented frame

Revision E includes this FC03 readout example. It is a manufacturer example, not a capture from an EpiSensor test installation.

Function
FC03 Read Holding Registers
Literal PDU address
0x5B00 = 23296 decimal
Quantity
2 registers, 4 data bytes
Request PDU
03 5B 00 00 02; configured slave address and CRC surround the PDU
Response data
00 00 09 05; high word first, high byte first
Decode
Unsigned 2309 × 0.1 V = 230.9 V
Acceptance
Use a wiring system with L1-N measurement and compare against the simultaneous front display

Acceptance: The address and response are from ABB’s worked example, independently decoded here. This validates the documented representation, not the wiring, transformer configuration or physical communications of an installed meter.

  1. Identify the Steel RS-485 meter

    Read A44 112-100 and 2CMA100248R1000 from the device documentation. Record firmware. Use the installation diagram for the actual three- or four-wire circuit, and have the authorised installer confirm the CT and VT connections.

  2. Check transformer ratios before collecting energy

    Record primary and secondary CT values and any VT ratio. The manual states that energy registers store primary values; do not multiply energy by the CT/VT ratio again in Edge. Compare current and voltage with the meter display before adding derived calculations.

  3. Select Modbus and match the bus

    In Settings, open the communication interface and choose Modbus, not EQ-Bus. Match speed, address and parity in Edge. Follow the three-wire A/B/Common line topology and terminate the two bus ends as documented.

  4. Read the literal voltage address

    Send FC03 to 0x5B00, decimal 23296, for quantity 2. ABB says Start Reg is sent exactly as printed: do not subtract one or add a 40000 prefix. Decode an unsigned 32-bit value, high word first, then multiply by 0.1 V.

  5. Reject unavailable values and verify energy

    Reject all-FFFF unsigned values before scaling. Add only Steel-supported quantities and compare the change in 0x5000 energy with the front display over a known interval. Leave configuration, output, reset and history-selection writes outside this monitoring setup.

Common questions

Why does the common map contain functions absent from my meter?
It covers A43 and A44 across several functionality levels. Steel is active-import energy; higher tiers add other counters and history. Unsupported quantities can return a normal response containing an invalid value, so a successful reply is not proof that the measurement exists.1
Should I apply the CT ratio to imported kWh again?
No. ABB states that transformer-connected energy registers store primary values using the configured total transformer ratio. First verify that ratio in the meter; multiplying the returned energy again would overstate consumption.1
Is 0x5B00 a one-based reference?
No. The manual explicitly says Start Reg is the value sent on the bus and must not be decremented or reduced by 40000. The worked FC03 request uses bytes 5B 00.1
Why is no prepared Edge template provided?
The meter represents missing unsigned quantities as all FFFF words and missing signed quantities as the maximum positive code. These are finite numbers. A reliable import needs raw sentinel rejection per data type and exact Steel point coverage before automatic polling can be presented as ready.1

Sources

  1. A43/A44 user manual, 2CMC484001M0201 revision E (opens in a new tab) (PDF) ABB
  2. ABB energy-meter catalogue, A44 ordering table (retained official reader extract) (opens in a new tab) (PDF) ABB

Further reading

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