What This Module Does
M0306 is an embedded protocol conversion module that converts Modbus RTU slave devices into PROFIBUS DP slave devices. It is designed for OEM manufacturers who want to add PROFIBUS DP communication capability to their existing Modbus instruments without redesigning the entire product.
The module is embedded directly into Modbus protocol devices — such as transmitters, motor drives, electrical measurement devices, and other industrial instruments — and communicates with the user board via TTL-level UART using the Modbus RTU protocol. The M0306 serves as the Modbus master on the field-device side and as a PROFIBUS DP slave on the control system side, converting data between the two protocols.
This means you can take an existing Modbus instrument and turn it into a PROFIBUS DP-compliant field device with minimal hardware changes and no protocol stack development.
Who Uses It
OEM manufacturers of industrial instruments who need to add PROFIBUS DP communication to their product lines. Product engineers looking to upgrade Modbus-based devices — transmitters, motor protection devices, power measurement instruments, smart electrical equipment — to support PROFIBUS DP without developing a PROFIBUS stack from scratch.
The M0306 is particularly valuable for manufacturers who want to quickly enable PROFIBUS DP communication on their instruments without purchasing a PROFIBUS development system or writing protocol software. It’s a drop-in module that gets you to market faster.
How It Works
The M0306 sits between the PROFIBUS DP network and the Modbus device. It connects to the main control board of the field device through a 16-pin connector — externally connected to the PROFIBUS DP network via the user’s PCB, internally connected to the user board via TTL-level UART.
Data flow direction:
- Modbus to PROFIBUS: The module, acting as a Modbus master, reads data from the user board (Modbus slave) via TTL-level UART using configured Modbus commands. The data is then mapped to PROFIBUS DP input data and made available to the PROFIBUS master control system.
- PROFIBUS to Modbus: When the PROFIBUS master sends output data, the module maps the data to Modbus commands and writes it to the user board via TTL-level UART.
Key mapping concept:
User Board Modbus Data ↔ M0306 ↔ PROFIBUS DP Master I/O Data
The module supports up to 244 bytes of input data, 244 bytes of output data, and a combined total of 360 bytes. All mapping is configured through the Modbus General Configuration Tool.
Modbus Data and PROFIBUS Data Mapping
The M0306 maps user board Modbus data to PROFIBUS DP I/O data. The mapping is configured by setting up Modbus commands that the module will execute cyclically.
Read coil input: The module reads coil status data from the user board’s digital storage area (0xxxx/1xxxx) via 01H or 02H commands. The data is packed into bytes and sent to the PROFIBUS input area.
Read register input: The module reads analog data from the user board’s register storage area (3xxxx/4xxxx) via 03H or 04H commands. Each register value occupies 2 bytes in the PROFIBUS input area.
Write coil output: The module receives output data from the PROFIBUS master, unpacks it, and writes it to the user board’s digital storage area via 05H or 0FH commands.
Write register output: The module receives output data from the PROFIBUS master and writes it to the user board’s register storage area via 06H or 10H commands.
Up to 20 Modbus commands can be configured, each specifying: function code, register address, data quantity (coils or registers), and update mode.
Hardware Interface
The M0306 uses a 2.54mm pitch 16-pin connector (J4) to connect to the user board.
Pin definition (J4):
| Pin | I/O | اسم | Description |
|---|---|---|---|
| 1 | I | IVCC | 5.0V / 3.3V DC isolated power |
| 2 | O | OVCC | Ground for IVCC |
| 3 | I | CPU Reset | Reset, low active |
| 5 | O | TxD | MCU UART transmitter |
| 8 | I | RxD | MCU UART receiver |
| 9 | O | DP_CNTR | Connect to pin 4 of PROFIBUS DB9 connector |
| 10 | O | LED_DP | DP communication status indication |
| 11 | I/O | DP_B | Connect to pin 3 of PROFIBUS DB9 connector |
| 12 | I/O | DP_A | Connect to pin 8 of PROFIBUS DB9 connector |
| 15 | I | 5V_ISO | 5V isolation power supply |
| 16 | O | OV | Isolation power ground (isolated from GND) |
DIP switch (S1):
The 8-bit DIP switch provides PROFIBUS DP slave address setting and working mode selection:
| Switch | Description |
|---|---|
| 1 | If ON, address +1 |
| 2 | If ON, address +2 |
| 3 | If ON, address +4 |
| 4 | If ON, address +8 |
| 5 | If ON, address +16 |
| 6 | If ON, address +32 |
| 7 | If ON, address +64 |
| 8 (MM) | ON = Configuration mode, OFF = Normal operating mode |
LED indicators:
| LED | دالة |
|---|---|
| LED1 (DP) | PROFIBUS DP communication status |
| LED2 (Modbus) | Modbus communication status |
Two Working Modes
The M0306 supports two operating modes, switchable via the DIP switch (S1.8):
Configuration Mode (S1.8 = ON):
- M0306 acts as a Modbus slave
- Modbus General Configuration Tool acts as the Modbus master
- Used for configuring: Modbus communication parameters, Modbus command queue, device ID, and other settings
- Configuration data is downloaded to the module via the configuration tool
Normal Operating Mode (S1.8 = OFF):
- M0306 acts as a Modbus master on the device side
- M0306 acts as a PROFIBUS DP slave on the control system side
- Cyclically executes the configured Modbus command queue to read/write user board data
- Exchanges I/O data with the PROFIBUS master control system in real time
Configuration Overview
The M0306 is configured using the Modbus General Configuration Tool provided by Microcyber.
Configuration steps:
- Set S1.8 to ON (Configuration Mode) and power on the module
- Connect the module to a PC via a TTL serial device
- Open the Modbus General Configuration Tool and add the device
- Configure the following parameters:
- Modbus communication parameters: Baud rate (2400-19200), data bits (8), parity (None/Even/Odd), stop bits, slave address
- Modbus input/output control parameters: Modbus command function code, register address, data quantity, update mode
- PROFIBUS communication parameters: Device ID, I/O configuration data
- User parameters: Parameters that don’t need real-time updates, transmitted only during initialization
- Serial port set DP address parameters: Enable/disable reading DP address from user board
- Save the configuration to the module
- Set S1.8 to OFF (Normal Operating Mode) and power cycle the module
Batch download: For manufacturers with multiple modules requiring the same configuration, save the configuration to a file and batch download to all modules.
GSD File and Device ID
The M0306 module uses a GSD file for PROFIBUS DP integration. The module is sold as an OEM product, meaning users have independent intellectual property rights for their PROFIBUS devices. Users can generate their own GSD files with their company name, product model, and serial number using the Modbus General Configuration Tool.
Key GSD file information:
- File naming convention: 8-character string (4 characters for manufacturer + 4 characters for device ID)
- Example: MCYB0FC5.gsd (MCYB = Microcyber, 0FC5 = device ID)
- Users can replace the manufacturer name abbreviation when applying for a device ID
- The device ID configured in the module must match the device ID in the GSD file
Device ID application:
- Apply for membership in the PI organization
- Apply for a device ID through the PI Certification Center (certification@profibus.com)
- Copy the application to PI-China (info@pi-china.org.cn)
- Create a custom GSD file with the assigned ID
Product certification testing is optional but recommended for greater customer confidence and easier participation in project bidding.
Technical Specifications
| معامل | مواصفات |
|---|---|
| Power supply (MCU) | 5.0V / 120mA or 3.3V / 100mA |
| DP bus baud rate | Self-adapting, 9.6K to 12Mbps |
| Protocol before conversion | مودباص آر تي يو |
| Protocol after conversion | بروفيباس دي بي |
| Max input data | ≤244 bytes |
| Max output data | ≤244 bytes |
| Max total I/O data | ≤360 bytes |
| Max user data | ≤200 bytes |
| Max I/O configuration data | ≤20 bytes |
| Temperature range | -40°C to 85°C |
| Humidity range | 5-95% RH |
| Startup time | ≤٥ ث |
| وزن | 14g |
| Dimensions (L×W×H) | 65×42×14 mm |
| EMC compliance | GB/T 18268.1 |
Supported Modbus Function Codes
| Code | Operation |
|---|---|
| 01H | Read coil status |
| 02H | Read input status |
| 03H | Read holding registers |
| 04H | Read input registers |
| 05H | Set single coil |
| 06H | Preset single register |
| 0FH | Force multiple coils |
| 10H | Preset multiple registers |
Troubleshooting
| Problem | Possible Cause | حل |
|---|---|---|
| Modbus communication failure | Incorrect baud rate / parity / slave address | Check Modbus communication parameters in configuration |
| DP communication failure | Incorrect DP address / GSD file mismatch | Check S1 DIP switch settings, verify device ID |
| LED2 off | No Modbus communication / Slave failure | Check user board connection and configuration |
| LED1 off | No DP communication / Power failure | Check PROFIBUS DP network and power |
For detailed diagnostic information, use the Modbus General Configuration Tool’s device monitoring function to view Modbus communication failure codes and identify which command is failing.
Need to add PROFIBUS DP to your Modbus instruments? Contact our OEM support team for integration assistance.