The M31 Series is a high-performance distributed I/O host featuring an 8DI+8DO configuration, dual Ethernet ports with built-in switch functionality, and Modbus TCP/RTU support, engineered with a 1ms internal bus speed and a conformal-coated enclosure for rugged industrial data acquisition.
M31-U Series Selection Guide
The M31-U series consists of Hosts (Master Modules) and Expansion Modules (Slaves).
- Hosts (Suffix: G-U): Equipped with Dual RJ45 (Modbus TCP) + RS485 (Modbus RTU).
- Expansions (Suffix: -U): Connect directly to the Host via the 1ms high-speed backplane bus (No Ethernet required).
*Naming Convention Note: The 4 digits near the end of the SKU represent the channel count (DI / DO / AI / AO). The letter 'A' represents 16 channels. Different letter prefixes (A, B, E, F) denote the hardware sub-type (e.g., Relay vs. Transistor DO, Voltage vs. Current AI).
| I/O Category | Host Module (Dual RJ45 + RS485) |
Expansion Module (Backplane Bus) |
DI | DO | AI | AO |
|---|---|---|---|---|---|---|
| Mixed I/O | M31-AFAX4440G-U | M31-GAFAX4440-U | 4 | 4 | 4 | 0 |
| M31-AXAX8080G-U M31-AXEX8080G-U |
M31-GAXAX8080-U M31-GAXEX8080-U |
8 | 0 | 8 | 0 | |
| M31-AXAX4040G-U | M31-GAXAX4040-U | 4 | 0 | 4 | 0 | |
| Digital Input (DI) | M31-AXXXA000G-U | M31-GAXXXA000-U | 16 | 0 | 0 | 0 |
| M31-AXXX8000G-U | M31-GAXXX8000-U | 8 | 0 | 0 | 0 | |
| Digital Output (DO) | M31-XAXX0A00G-U M31-XBXX0A00G-U |
M31-GXBXX0A00-U | 0 | 16 | 0 | 0 |
| M31-XFXX0800G-U | M31-GXFXX0800-U | 0 | 8 | 0 | 0 | |
| M31-XDXX0600G-U | M31-GXDXX0600-U | 0 | 6 | 0 | 0 | |
| Analog Input (AI) | M31-XXAX00A0G-U M31-XXEX00A0G-U |
M31-GXXAX00A0-U M31-GXXEX00A0-U |
0 | 0 | 16 | 0 |
| (Expansion Only) | M31-GXXAX0080-U | 0 | 0 | 8 | 0 | |
| Analog Output (AO) | M31-XXXA0008G-U M31-XXXB0008G-U |
M31-GXXXA0008-U M31-GXXXB0008-U |
0 | 0 | 0 | 8 |
Download Manual
User Manual
Configuration Tool
Company Profile
| Key Parameter | Specification |
|---|---|
| Series Model | Ebyte M31 Series Distributed IO Host |
| I/O Configuration | 8 Digital Inputs (DI) + 8 Digital Outputs (DO) |
| Communication Interface | Dual RJ45 (10/100M Adaptive), RS485 |
| Supported Protocols | Standard Modbus TCP, Modbus RTU |
| Operating Voltage | DC 9 ~ 36V (Wide voltage input) |
| Internal Bus Speed | Up to 1ms for high-speed synchronization |
| Protection Features | Three-proof paint (Anti-mold, moisture, salt spray) |
| Installation & Size | DIN Rail / Positioning hole | 110 * 40 * 100 mm |
Application
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Factory Automation & Conveyor Control: In high-speed packaging lines, the M31 series utilizes its ultra-fast 1ms internal bus speed to ensure real-time synchronization between optical sensors (DI) and pneumatic pushers (DO), eliminating mechanical latency and improving production throughput.
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Water Treatment & Chemical Plants: Harsh industrial environments easily degrade standard electronics. The M31 series solves this with its three-proof conformal coating (anti-mold, anti-humidity, anti-salt spray), ensuring stable data acquisition of pump statuses and valve controls in highly corrosive atmospheres.
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Smart Grid & Substation Monitoring: Power fluctuations are common in substations. The M31 series accommodates this with a wide DC 9~36V input range. Furthermore, its "disconnection output reset" function acts as a critical failsafe; if the central SCADA system connection drops, the module automatically resets outputs to a pre-configured safe state, preventing catastrophic equipment overloads.
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Large-Scale HVAC Systems: Wiring multiple IO modules across a large facility can be expensive. The M31 features dual 10/100M adaptive Ethernet ports with built-in switch functionality, allowing integrators to daisy-chain modules in a linear topology, drastically reducing ethernet cable runs and external switch costs.
FAQ
Q: How does the wide input voltage of DC 9~36V affect the internal logic circuits of the M31 module?
A: The device utilizes a high-efficiency internal step-down DC-DC switching regulator that actively stabilizes the voltage provided to the MCU and communication ICs. This wide tolerance protects the internal 3.3V and 5V logic rails from transient voltage dips or surges commonly caused by heavy inductive loads or motor start-ups sharing the same industrial power supply rail.
Q: Can you explain the electrical mechanics behind the dual Ethernet ports acting as a switch?
A: The dual 10/100M adaptive RJ45 ports interface directly with an internal unmanaged ethernet switch IC rather than separate MAC addresses on the MCU. This MAC-level bridging allows network packets not destined for the specific module to be forwarded to the next port with minimal microsecond latency, enabling seamless daisy-chaining without impedance mismatch issues over long CAT5e cable runs.
Q: What exactly happens at the hardware level during a "disconnection output reset"?
A: When the internal watchdog timer detects an absence of valid Modbus TCP or RTU polling frames beyond the user-configured timeout threshold, the MCU interrupts its normal routine and forces the logic gate drivers controlling the DO channels to a predefined safe state. This immediately opens or closes the relay contacts or optocouplers, ensuring external actuators do not remain energized blindly during a network failure.
Q: How does the three-proof paint physically protect the PCB and surface-mount components?
A: The three-proof paint is a dielectric conformal coating sprayed over the assembled circuit board. It cures to form a microscopic insulating barrier that dramatically increases surface insulation resistance. This prevents the formation of conductive dendritic growth between tightly spaced SMD component pins when exposed to condensation, salt mist, or corrosive gases, thereby preventing logic short circuits and leakage currents.
