Iskra WM3M4 (MID EV meter)

Status: Vendor Confirmed · Register points: 87 · Transports: Modbus RTU

A curated ModDef profile for the Iskra WM3M4 (MID EV meter). Import it as iskra.wm3m4 or load the .moddef.yaml directly.

Connect to one over Web Serial and watch its values live in the device dashboard.

Usage

Load the profile, bind a transport, and read a point by name. The runtime applies the offset, scaling, byte order, and sentinels from the definition.

doc, _ := moddef.Load("iskra-wm3m4.moddef.yaml")
dev, _ := client.New(doc, "iskra-wm3m4", transport) // your modbus.Transport
v, _ := dev.ReadPoint(ctx, "frequency")
fmt.Println(v)

import {Device} from '@moddef/core';
import {loadDocument} from '@moddef/core/node';

const doc = await loadDocument('iskra-wm3m4.moddef.yaml');
const dev = Device.create(doc, 'iskra-wm3m4', transport);
console.log(await dev.readPoint('frequency'));

let doc = moddef_core::load("iskra-wm3m4.moddef.yaml")?;
let mut dev = Device::new(&doc, Some("iskra-wm3m4"), transport)?;
let v = dev.read_point("frequency").await?;

from moddef import Device, load
from moddef.pymodbus import Options, PymodbusTransport

doc = load("iskra-wm3m4.moddef.yaml")
transport = await PymodbusTransport.tcp("192.168.1.50", options=Options())
dev = Device.create(doc, "iskra-wm3m4", transport)
print(await dev.read_point("frequency"))

md_doc_t doc;
md_doc_init(&doc, flash_ptr, flash_len);        /* zero-copy view */

md_dev_t dev;
md_dev_init(&dev, &doc, MD_STR("iskra-wm3m4"), &transport);

md_value_t v;
md_dev_read(&dev, MD_STR("frequency"), &v);

auto doc = moddef::Document::view(flash_bytes).value();   // zero-copy over flash
auto dev = moddef::Device::open(doc, "iskra-wm3m4", transport).value();

if (auto v = dev->read("frequency"); v)
    std::cout << v->to_string() << '\n';

Commands

Multi-step register procedures (spec §11.7) this profile defines — write params, arm a trigger, poll for completion, then read the result. Run one with your language's command executor (RunCommand, runCommand, run_command, or md_cmd_begin/md_cmd_tick in C/C++).

`begin_transaction` — Begin Transaction

Write the billing dataset and start a signed billing transaction ('B'); set datetime_sync, timezone_offset and signature_format first (manual SS6.4 step 1)

Params

Field	Type	Required
`dataset`	BYTES	yes
`dataset_length`	UINT32	yes

Results

Field	Type
`status`	UINT32

`end_transaction` — End Transaction

End the signed billing transaction ('E'), wait for the signature, then fetch the signed output message, its signature and the public key (manual SS6.4 steps 8-14)

Results

Field	Type
`message`	BYTES
`length`	UINT32
`signature`	BYTES
`signature_length`	UINT32
`public_key`	BYTES

Measurands

The 9 semantic quantities this device reports, each linked to the measurand catalog. Query a device by measurand instead of a raw point when you want portable code.

Base quantity	Name	Unit	Description
`frequency`	Frequency	`Hz`	Grid frequency
`voltage`	Voltage	`V`	RMS voltage; qualify with phase_ref (L1_N, L1_L2, ...)
`current`	Current	`A`	RMS current; qualify with phase_ref / direction
`active_power`	Active Power	`W`	Instantaneous real power
`reactive_power`	Reactive Power	`var`	Instantaneous reactive power
`apparent_power`	Apparent Power	`VA`	Instantaneous apparent power
`power_factor`	Power Factor	`1` (ratio)	Ratio of real to apparent power (dimensionless)
`energy_active`	Active Energy	`Wh`	Cumulative active energy register
`temperature`	Temperature	`degC`	Temperature; qualify with location (INTERNAL, EXTERNAL, ...)

Source

Profile: energy-meter/iskra-wm3m4/iskra-wm3m4.moddef.yaml
Register map: vendor documentation

Usage​

Commands​

begin_transaction — Begin Transaction​

end_transaction — End Transaction​

Measurands​

Source​