Product Overview
The ProSoft 3300-MBP is a Modbus Plus communication module designed to bridge Allen-Bradley 1771 I/O compatible processors with Modbus Plus networks, enabling seamless data exchange between Rockwell Automation control systems and Modicon PLCs or other Modbus Plus-compatible end devices . As a gateway module residing in the PLC backplane, the ProSoft 3300-MBP offloads Modbus Plus communication processing from the host processor, allowing the PLC to focus on control logic execution while the module manages network traffic asynchronously . This architecture is particularly valuable in legacy installations where existing PLC-5 or SLC systems require integration with Modbus Plus networks without replacing the primary controller.
The ProSoft 3300-MBP maintains a 4000-word register space that serves as the shared data buffer between the PLC data table and the Modbus Plus network . This memory is logically divided into 80 blocks of 50 words each, with data paged bi-directionally between the module and the PLC processor via Block Transfer Read (BTR) and Block Transfer Write (BTW) instructions . The module supports both Master and Slave operating modes, allowing it to actively issue read/write commands to other network nodes or respond to requests from Modicon PLCs . Available in single-port and redundant-port hardware configurations, the ProSoft 3300-MBP provides a flexible solution for integrating legacy Allen-Bradley systems into Modbus Plus network architectures .
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | ProSoft 3300-MBP |
| Manufacturer | ProSoft Technology |
| Product Type | Modbus Plus Communication Module (1771 I/O compatible) |
| Compatible Platforms | Allen-Bradley PLC-5, SLC, and 1771 I/O processors |
| Modbus Plus Ports | 1 (single port) or 2 (redundant port configuration) |
| Configuration Port | RS-232 (front-panel DB-9) |
| Internal Data Space | 4000 words (16-bit registers), organized as 80 blocks × 50 words |
| Node Address Range | 1 to 64 (DIP switch configurable) |
| Global Out Size | 0, or 1 to 32 words |
| Master Commands | 0, or 1 to 100 commands |
| Backplane Interface | BTR/BTW Block Transfer via PLC ladder logic |
| Operating Temperature | 0°C to +60°C (typical industrial range) |
Main Features and Advantages
Dual-mode Master/Slave operation: The ProSoft 3300-MBP can function as either an active Master issuing commands to other Modbus Plus nodes or as a Slave responding to read/write requests from Modicon PLCs and other network masters . This flexibility allows a single module type to serve multiple integration scenarios, from pulling data from remote drives and relays to exposing PLC data to a supervisory Modicon system. The Master Command List supports up to 100 individual read or write commands, each capable of transferring 1 to 100 words per operation .
Redundant network path support: The redundant-port hardware configuration of the ProSoft 3300-MBP provides two parallel Modbus Plus ports that operate as a single logical network across two physical cable paths . If communication is lost on one cable path, the other path continues operating normally without interruption to data exchange. This redundancy is critical in continuous-process industries where a single cable fault should not sever the connection between the PLC and its Modbus Plus peers.
Deterministic data exchange via Global Data: The ProSoft 3300-MBP prioritizes Global In and Global Out data to provide a high-speed mechanism for transferring control data across the Modbus Plus network . Up to 32 words of Global Output data can be broadcast from the PLC, while the module accepts up to 32 words per node from up to 32 nodes. This peer-to-peer data sharing mechanism is ideal for coordinating interlocks and status signals between multiple controllers without the overhead of explicit command polling.
Legacy system preservation: For facilities operating Allen-Bradley PLC-5 or SLC systems with Modbus Plus connectivity requirements, the ProSoft 3300-MBP provides a direct backplane-compatible solution that avoids the cost and disruption of controller migration . The module integrates through standard BTR/BTW ladder logic, using example logic provided by ProSoft as a starting point, and requires only DIP switch node address configuration and data table setup to become operational .
