What This Module Does
The M0310-ACT is an embedded protocol conversion module that converts Modbus RTU slave devices into HART slave devices. It is designed for field device manufacturers who want to add HART communication capability to their existing Modbus instruments without redesigning the entire product.
The module is embedded directly into Modbus protocol input devices — such as valve positioners, electric actuators, flow meters, and other measuring instruments — and runs the Modbus application layer protocol through TTL level signals. The M0310-ACT serves as the Modbus master and the HART slave, converting data from Modbus data registers (input registers, holding registers) into dynamic variables used in HART commands.
This means you can take an existing Modbus instrument and turn it into a HART-enabled field device with minimal hardware changes.
Who Uses It
OEM manufacturers of industrial instruments who need to add HART 7.0 communication to their product lines. Product engineers looking to upgrade Modbus-based devices — valve positioners, electric actuators, flow meters, level transmitters — to support HART without developing a HART protocol stack from scratch.
The M0310-ACT is particularly valuable for manufacturers who want to quickly enable HART communication on their instruments without writing protocol software or redesigning hardware. It’s a drop-in module that gets you to market faster.
Como Funciona
The M0310-ACT sits between the HART bus and the Modbus device. It plugs into the main control board of the field device through a back socket — externally connected to the HART bus, internally connected to the field device.
Data flow direction:
- Modbus to HART: The module, acting as a Modbus master, reads data from the user board (Modbus slave) via TTL-level UART. The data is then mapped to device variables (0-5) and further mapped to HART dynamic variables (PV, SV, TV, QV).
- HART to Modbus: When a HART master sends a HART command (e.g., writing PV range limits), the module parses the command, maps the data back to Modbus holding registers, and writes it to the user board.
Key mapping concept:
Modbus Register Data → Device Variable (n) → Dynamic Variable (PV/SV/TV/QV)
For example, if a holding register at address 30000 in an actuator stores the instantaneous flow value, the register can be configured to device variable 0, which is then assigned as the primary variable (PV). This mapping is fully configurable.
Hardware Interface
The M0310-ACT uses a 2.54mm pitch 16-core standard socket (JP1) to plug into the user board.
Pin definition (JP1):
| Fixar | I/O | Nome | Descrição |
|---|---|---|---|
| 1 | I | VCC | 3.3V/5V DC power from user PCB |
| 2 | I | GND | Ground reference |
| 5 | O | TxD | MCU UART transmitter |
| 6 | I | RDY | Device status bit |
| 8 | I | RxD | MCU UART receiver |
| 11 | I | +24V | 24V power positive (HART circuit) |
| 12 | I | -24V | 24V power negative (HART circuit) |
| 13 | I/O | HART+ | HART input/output positive |
| 14 | I/O | HART- | HART input/output negative |
External terminal (JP4):
| Fixar | Descrição |
|---|---|
| 1 | HART- (communication negative) |
| 2 | HART+ (communication positive) |
| 3 | HART- (communication negative) |
| 4 | HART+ (communication positive) |
| 5 | 24V- (power negative) |
| 6 | 24V+ (power positive) |
LED indicators:
| LED1 | LED2 | Status |
|---|---|---|
| On | On | Module initialization, not yet in working status |
| On | Flashing | HART communication active |
| Flashing | On | Modbus communication active |
| Off | Off | No communication or fault status |
Supported wiring configurations:
The M0310-ACT currently supports three-wire e four-wire equipment only. It does not support two-wire equipment (field devices with current consumption ≤4mA).
- Three-wire equipment: Powered by two power lines, with a third line forming the HART bus with the positive power line for 4-20mA and HART communication. Used for devices with current consumption >4mA, such as Coriolis mass flow meters and most electromagnetic flow meters.
- Four-wire equipment: Powered by two power lines, with the other two lines connected to the HART bus for 4-20mA and HART communication. Same purpose as three-wire equipment.
HART Protocol Support
The M0310-ACT implements the HART 7.0 protocol and supports Burst mode operation. It supports both common and general HART commands.
| Comando | Descrição | Comando | Descrição |
|---|---|---|---|
| 0 | Read unique identifier | 33 | Read device variables |
| 1 | Read PV unit and value | 34 | Write PV damping value |
| 2 | Read PV current and percentage | 35 | Write PV range values |
| 3 | Read dynamic variables and PV current | 36 | Set PV upper range with current value |
| 6 | Write polling address | 37 | Set PV lower range with current value |
| 7 | Read polling address | 40 | Enter/exit fixed current mode |
| 8 | Read dynamic variable categories | 41 | Device self-test |
| 9 | Read device variables and status | 42 | Device self-reset |
| 11 | Read device ID using tag | 43 | Set PV zero with current value |
| 12 | Read message | 44 | Write PV unit |
| 13 | Read tag, descriptor, date | 45 | Adjust loop low current (4mA) |
| 14 | Read PV sensor information | 46 | Adjust loop high current (20mA) |
| 15 | Read PV output information | 47 | Write PV transfer function |
| 16 | Read final assembly number | 49 | Write PV sensor serial number |
| 17 | Write message | 50 | Read dynamic variable assignment |
| 18 | Write tag, descriptor, date | 51 | Write dynamic variable assignment |
| 19 | Write final assembly number | 53 | Write device variable units |
| 20 | Read long tag | 59 | Write number of preamble characters |
| 21 | Read device ID using long tag | 38 | Reset configuration change flag |
| 22 | Write long tag | 48 | Read additional transmitter status |
Actuator-specific commands (136, 137, 146, 147):
| Comando | Descrição |
|---|---|
| 136 | Read actuator type (DISABLE, POSITIONER, ON-OFF) |
| 137 | Write actuator type |
| 146 | Read actuator specific parameters (STOP, CLOSE, OPEN, ESD, SETPOINT) |
| 147 | Write actuator specific parameters |
Modbus Interface
The M0310-ACT communicates with the user board using the Modbus RTU protocol over TTL-level UART. The module serves as the Modbus master; the user board serves as the slave.
Default communication parameters:
| Parâmetro | Default | Optional range |
|---|---|---|
| Slave address | 1 | 1-247 |
| Baud rate | 9600 | 1200, 2400, 4800, 9600, 19200, 35700, 38400, 57600 |
| Data bits | 8 | 7, 8 (only 8 valid for RTU) |
| Stop bits | 1 | 1, 2 |
| Parity | EVEN | ODD, EVEN, NONE |
| CRC byte order | Low-High | Low-High, High-Low |
Supported Modbus function codes:
| Código | Operation |
|---|---|
| 1 | Read coil status |
| 2 | Read discrete input status |
| 3 | Read holding registers |
| 4 | Read input registers |
| 5 | Write single coil |
| 16 | Write multiple registers |
Configuration Overview
The M0310-ACT is configured using the HartMPT configuration software from Microcyber, or any HART master with DD file parsing capability (such as a PC or handheld communicator with the provided DD file).
Three configuration steps:
- Configure Modbus interface — Set slave address, baud rate, data bits, parity, stop bits, and CRC byte order to match the user board’s interface characteristics.
- Configure device variables — Map Modbus data registers to the module’s six device variables (0-5). Each variable requires: type, unit, sensor range limits, Modbus function code, register address, and data type.
- Configure dynamic variables — Map device variables to HART dynamic variables (PV, SV, TV, QV) based on the application requirements.
Operation modes:
| Mode | Descrição |
|---|---|
| Configuration Mode | HART module does not actively send Modbus requests. All settings can be modified. |
| Operation Mode | HART module cyclically sends Modbus requests to the user board and makes data available on the HART bus. |
Device Variable Configuration
The M0310-ACT supports six device variables (0-5). Each variable requires the following parameters:
| Parâmetro | Descrição |
|---|---|
| Digitar | Data type (volume flow, temperature, pressure, density, etc.) |
| Unidade | Engineering unit for HART device data (in PV) |
| Sensor range upper limit | Maximum limit value of the device variable |
| Sensor range lower limit | Minimum limit value of the device variable |
| Minimum span | Range span (typically sensor upper limit divided by 100) |
| Upper range limit | Between sensor upper and lower limits |
| Lower range limit | Between sensor upper and lower limits |
| Default units | Units of variable read from Modbus device |
| Modbus function code | Function code for reading the device variable |
| Register address | Data register address in Modbus device |
| Register data type | Byte order of data in Modbus registers |
PV Range Configuration
Users can configure the source and read/write mode of the primary variable (PV) range limits through the PV Range option group.
PV Range Source:
- Local: Manually configured through configuration software
- Remote: Read from the user’s Modbus device
PV Range Operation Mode:
- Read and Write: HART module can both read from and write to the user’s Modbus device
- Read Only: HART module only reads range limits from the user’s Modbus device
Register Data Type: Format in which range limits are stored in Modbus registers.
Scaling Factor
Each device variable has a scaling factor parameter:
HART device variable n = Modbus device variable n × scaling factor
Factory default is 1.0. Modify only if scaling is required.
Device Status
The M0310-ACT provides HART additional device status (3 bytes):
- Byte 1: Lower 6 bits indicate whether reading of the six device variables was successful (0: success, 1: fault or misconfigured)
- Byte 2-3: 16 states representing the user’s Modbus device status
Users can configure the status of Modbus devices to the HART additional device status through the ‘Device Status’ option group. Each bit of the device status used is determined by the ‘Bit mode’ (1-16).
Data Preservation and Recovery
| Função | Descrição |
|---|---|
| Restore to factory defaults | Restores all configuration data to system initial values (use with caution) |
| Save to factory settings | Saves current user configuration as factory values |
| Restore to factory settings | Restores previously saved user configuration |
Batch Download
A quick configuration function for manufacturers with multiple M0310-ACT modules:
- Configure one module completely
- Click “Save to File” to save the configuration
- For other modules, click “Open File” to load the configuration
- Click “Batch Download Data” to apply to all modules
Technical Specifications
| Parâmetro | Especificação |
|---|---|
| Fonte de alimentação | 6-42 VDC (across device terminals) |
| Bus protocol | 2-wire HART |
| Resistência de carga | 0-1500Ω (normal) / 230-1100Ω (HART communication) |
| Tensão de isolamento | 500V AC between Modbus and HART |
| Intervalo de temperatura | -40 °C a 85 °C |
| Humidity range | 5-95% RH |
| Startup time | ≤5s |
| Atualizar hora | 0,2s |
| Damping adjustment | Time constant 0-32 seconds |
| Output current accuracy | Maximum error ≤50µA across full temperature range |
| Dimensões | 65mm × 42mm × 17mm |
Electrical interface:
| Fixar | Nome | Descrição |
|---|---|---|
| 1 | VCC | 3.3-5V DC isolated power from user board |
| 2 | GND | VCC reference ground |
| 5 | TxD | MCU UART transmitter |
| 8 | RxD | MCU UART receiver |
| 11 | +24V | Power positive |
| 12 | -24V | Power negative |
| 13 | H+ | HART input/output positive |
| 14 | H- | HART input/output negative |
Troubleshooting
| Problem | Causa Possível | Solução |
|---|---|---|
| No communication with instrument board | Connection failure / Multipoint mode | Check wiring / Check network |
| HART communication LED off | No HART communication / Power failure | Check HART host device and modem / Check power |
| Modbus communication LED off | No Modbus communication / Slave device failure | Check Modbus devices / Check connections |
| Dynamic variable reading incorrect | Device variable configuration incorrect / Modbus communication parameter incorrect | Check register address and data type / Check baud rate and parity |
Need to add HART 7.0 communication to your Modbus instruments? Contact our OEM support team for integration assistance.
