The FX3U-32DP is Mitsubishi Electric’s PROFIBUS-DP master station module for the MELSEC FX3U compact PLC series, enabling any FX3U base unit to act as a PROFIBUS-DP Class 1 master — managing cyclic data exchange with up to 32 PROFIBUS-DP slave devices including variable speed drives, remote I/O stations, valve manifolds, intelligent sensors, and third-party automation devices from any manufacturer supporting the PROFIBUS-DP standard. As the FX3U platform’s gateway to the PROFIBUS field network ecosystem, the FX3U-32DP provides cross-vendor interoperability for FX3U-based systems integrated into existing PROFIBUS infrastructure — particularly relevant for European and Asian installations where PROFIBUS-DP is the established field device communication standard alongside CC-Link. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the FX3U-32DP?
The FX3U-32DP is a MELSEC FX3U series special function module implementing the PROFIBUS-DP protocol at Class 1 master level, compliant with IEC 61158 and EN 50170, and installed in the FX3U extension bus alongside I/O expansion modules. As a Class 1 DP master, the FX3U-32DP manages cyclic I/O data exchange with up to 32 PROFIBUS-DP slave devices on a single PROFIBUS segment, reading input data from slaves and writing output data to slaves within a configurable bus cycle. The module supports PROFIBUS-DP V0 (basic cyclic data exchange) for standard remote I/O slaves and PROFIBUS-DP V1 (acyclic parameter access and slave diagnostics) for intelligent slaves such as Siemens SINAMICS drives, ABB ACS800 drives, and Festo CPX valve terminals — enabling drive parameter reading and configuration from the FX3U program without requiring separate commissioning tools. Network configuration is performed using GSD (Generic Station Description) files and Mitsubishi’s GX Configurator-DP software. The module’s data exchange results are mapped to FX3U device memory via auto-refresh for straightforward ladder program access.
Key Technical Specifications
- Model: FX3U-32DP
- Function: PROFIBUS-DP Class 1 master station
- Protocol: PROFIBUS-DP V0 and V1 (IEC 61158 / EN 50170)
- Maximum Slave Stations: 32
- Transmission Speed: 9.6 kbps to 12 Mbps (auto-detected)
- Total Input Data: Up to 4,096 bytes across all slaves
- Total Output Data: Up to 4,096 bytes across all slaves
- Bus Connector: 9-pin D-Sub female (RS-485)
- Extension Bus Occupation: 32 I/O points
- Current Consumption (FX3U bus): 0.12 A at 5 VDC
- Operating Temperature: 0°C to 55°C
- Compatible FX3U base units: All FX3U models
- Weight: Approx. 0.18 kg
Compatibility & System Integration
The FX3U-32DP is compatible with all PROFIBUS-DP V0 and V1 slave devices from any ODVA or PROFIBUS International member manufacturer. Siemens ET 200S and ET 200M distributed I/O, Siemens SINAMICS drives with PROFIBUS option board, ABB ACS800 with RPBA-01 PROFIBUS adapter, Festo CPX valve terminals with PROFIBUS interface, Pepperl+Fuchs PROFIBUS remote I/O, and Pilz PNOZmulti safety relays with PROFIBUS output are all compatible as slaves. For FX3U systems controlling Siemens variable speed drives on an existing PROFIBUS plant network managed by a Siemens SIMATIC S7 master, the FX3U-32DP enables an alternative control configuration where the FX3U acts as master for a dedicated machine-level PROFIBUS sub-network, while the Siemens master manages the plant-level network — the two networks operate independently. The FX3U-32DP data mapping in GX Works2 uses auto-refresh to assign PROFIBUS slave I/O data directly to FX3U M relay and D register addresses, enabling the FX3U ladder program to read PROFIBUS inputs and write PROFIBUS outputs using standard FX3U ladder instructions without special FROM/TO programming. Mitsubishi’s GX Configurator-DP software manages slave GSD file import, address assignment, and DP V1 acyclic communication configuration, with the generated network configuration data written to the FX3U-32DP module.
Troubleshooting Guide
If the FX3U-32DP reports communication errors after initial installation, the first diagnostic step is to verify the PROFIBUS network termination — install 220 Ω / 390 Ω (Siemens-style) or 150 Ω / 390 Ω active termination resistors at both physical ends of the PROFIBUS bus, and confirm that termination is disabled on all intermediate bus connectors. PROFIBUS termination errors are the leading cause of commissioning failures and typically manifest as all slaves reporting communication error simultaneously rather than individual slave faults. Check the transmission speed setting against the maximum cable length for the installed cable type — at 12 Mbps, the maximum segment length is 100 m with PROFIBUS Type A cable; at 1.5 Mbps, it is 200 m. If individual slave stations initialise correctly at low baud rate but fail at higher rates, the cable installation exceeds the distance limit for the selected speed. For individual slave communication faults (one slave failing while others remain operational), read the slave diagnostic data via GX Configurator-DP’s online diagnostic function — slave diagnostic bytes contain specific fault codes indicating incorrect configuration (module identifier mismatch), hardware fault, or data exchange error that direct the fault resolution. Verify that each slave’s GSD file version matches the installed firmware — using an outdated GSD file with a newer slave firmware version can cause module identifier mismatches that prevent slave initialisation.
Frequently Asked Questions
Q: Can the FX3U-32DP communicate with PROFIBUS-PA devices (process automation) in addition to PROFIBUS-DP?
A: No. The FX3U-32DP supports PROFIBUS-DP only — the RS-485-based variant used in factory automation for remote I/O and drive communication. PROFIBUS-PA uses a different physical layer (IEC 61158-2, Manchester-encoded current loop for intrinsically safe environments) and requires a PROFIBUS-PA segment coupler or link device to interface with the PROFIBUS-DP bus. PROFIBUS-PA devices can be integrated into a FX3U-32DP network via a PA/DP segment coupler (such as Pepperl+Fuchs KFD-series) that makes the PA devices appear as DP slaves to the FX3U-32DP master.
Q: What is the maximum data exchange volume per slave with the FX3U-32DP?
A: The FX3U-32DP supports up to 244 bytes of input data and 244 bytes of output data per slave station — the standard PROFIBUS-DP maximum per slave. Across all 32 slave stations, the total network input and output data volumes are limited to 4,096 bytes each, so the average usable data per slave in a fully populated 32-station network is 128 bytes input and 128 bytes output — adequate for all standard remote I/O and drive communication requirements.
Q: Does the FX3U-32DP support PROFISAFE for functional safety slave devices?
A: No. The FX3U-32DP implements standard PROFIBUS-DP and does not support the PROFISAFE safety protocol extension. Safety-rated I/O and safety devices requiring PROFISAFE communication cannot use the FX3U-32DP as their safety master. Standard PROFIBUS-DP devices without safety requirements are fully supported.
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