Compare three direct-connected Modbus energy meters
Start with the circuit and the exact order code. These three models measure current directly; none is the CT-input version of its family.
Choose for the installation
The current limit is the first dividing line: 100 A for the SDM630-Modbus V2, 65 A for this EM24 and 63 A for the iEM3155. Those limits do not replace cable sizing, protection, terminal capacity or the manufacturer’s installation requirements.
For larger feeders or an existing CT circuit, select a separately documented CT-input model. A similar family name does not make these direct-connected meters interchangeable with it.
| Selection question | Eastron SDM630-Modbus V2 SDM630-Modbus V2 | Carlo Gavazzi EM24 EM24DINAV93XISX | Schneider Electric iEM3155 A9MEM3155 |
|---|---|---|---|
| Current input | Direct, up to 100 A; no external CT input on this model Source | Direct, up to 65 A; AV9 input, not AV5 CT input Source | Direct, 0–63 A; not the iEM3255 CT-input model Source |
| Supported wiring | 1-phase 2-wire; 3-phase 3-wire or 4-wire Source | 1-phase 2-wire; 3-phase 3-wire or 4-wire Source | 1P+N; 3P; 3P+N Source |
| Voltage inputs | 100–276 V L-N; 173–480 V L-L Source | 230 V L-N / 400 V L-L nominal Source | 100–277 V / 173–480 V rated inputs Source |
| Power supply | Supply arrangement not verified in this comparison; check the unit wiring diagram Source | Self-powered from the measured supply Source | Supply arrangement not verified in this comparison; check the current installation manual Source |
| Mounting | 35 mm DIN rail Source | DIN rail; 71 × 90 × 64.5 mm Source | DIN rail; 90 × 95 × 69 mm Source |
| Interfaces | RS-485 Modbus RTU; two pulse outputs Source | RS-485 Modbus RTU; three digital inputs Source | RS-485 Modbus RTU; one digital input and one digital output Source |
| Legal metrology boundary | Exact MID approval not established here; Class B accuracy alone is not approval Source | Exact MID approval not established for this X ordering code; do not borrow PF-option approval Source | MID listed for this exact reference; check current certificate and installed markings for the intended use Source |
Plan the Edge connection
All three use an RS-485 Modbus RTU connection. Use the appropriate Gateway serial interface or ZMB-31, match the meter’s communication settings, and verify one live reading before loading the rest. These figures come from the same reviewed templates offered on the device pages.
The EM24 template covers the documented PFA/PFB/X RS-485 map; confirm that the installed firmware and complete order code use that protocol. Ethernet EM24 maps are different. The iEM3155 map must not be substituted for the more limited iEM3150.
| Selection question | Eastron SDM630-Modbus V2 SDM630-Modbus V2 | Carlo Gavazzi EM24 EM24DINAV93XISX | Schneider Electric iEM3155 A9MEM3155 |
|---|---|---|---|
| Template coverage | 22 read-only points; map revision 1.0.0 Source | 32 read-only points; map revision 1.0.0 Source | 29 read-only points; map revision 1.0.0 Source |
| Read function | FC04 Source | FC04 Source | FC03 Source |
| Value formats | float32 Source | int32, int16 Source | float32 Source |
| Phase L1-N voltage start | 0 (zero-based PDU); multiply by 1 Source | 0 (zero-based PDU); multiply by 0.1 Source | 3027 (zero-based PDU); multiply by 1 Source |
| Active export energy | Included in starter map Source | Included in starter map Source | Included in starter map Source |
| Decode order | float32: big bytes; high word first Source | int32: big bytes; low word first / int16: big bytes Source | float32: big bytes; high word first Source |
Open the exact setup guide
- Eastron SDM630-Modbus V2: SDM630-Modbus V2
- Carlo Gavazzi EM24: EM24DINAV93XISX
- Schneider Electric iEM3155: A9MEM3155
What this comparison does not establish
There is no overall score or preferred brand. Prices, stock, warranty terms and current certification acceptance are not compared. Where exact evidence is missing, the table says so. A missing starter-map point does not prove that the meter lacks that measurement.
Reviewed 2026-09-26. Each table cell links to its source; the Schneider hardware datasheet is dated 2020, while the linked setup guide carries the current reviewed register manual. Recheck procurement details and certification against the supplied unit.