1. Introduction
In process industries, seamless communication between shop-floor controllers (PLCs) and plant-wide Distributed Control Systems (DCS) is critical for centralized monitoring, decision-making, and operational efficiency. However, PLCs and DCS platforms often use different industrial communication protocols.
This case study demonstrates how the Anybus Communicator ABC4090-A was successfully implemented to enable real-time data transfer between a Siemens PROFINET PLC and a Honeywell ModbusTCP-based DCS. The integration allowed continuous monitoring of field processes from the control room without requiring hardware changes to either controller.
2. Project Objective
· Establish seamless communication between Siemens S7 PROFINET PLC and Honeywell ModbusTCP DCS.
· Enable real-time transfer of critical process data (temperature, pressure, flow rates, alarms).
· Improve operator visibility in the control room for faster and safer decision-making.
· Minimize downtime and reduce integration costs by using protocol conversion rather than full system replacement.
3. System Architecture
Field Level:
· Siemens PLC (PROFINET-based) connected to process field devices (sensors, actuators, drives).
Gateway Layer:
· Anybus ABC4090-A Communicator configured as a PROFINET Device on the PLC side and as a ModbusTCP Server for the DCS.
Control Room Level:
· Honeywell DCS (ModbusTCP Client) requesting data from the Anybus Communicator.
Data Flow:
1. PLC gathers real-time process data from field devices.
2. Anybus Communicator maps this data from PROFINET cyclic I/O to ModbusTCP holding/input registers.
3. Honeywell DCS polls the Modbus registers to display live process values on operator screens.
4. Implementation Steps
Step 1: Network Setup
· Siemens PLC was assigned a PROFINET device address.
· Anybus ABC4090-A was added as a PROFINET device in Siemens TIA Portal hardware configuration.
· Ethernet connection established between PLC, Anybus gateway, and DCS network.
Step 2: Anybus Configuration
· Using Anybus Configuration Manager (ABC Config Tool):
o Defined data transactions for PROFINET ↔ ModbusTCP mapping.
o Configured ModbusTCP registers to match Honeywell DCS tag database.
o Assigned IP addresses and ensured network compatibility.
Step 3: PLC Program Mapping
· In TIA Portal, created data blocks for process variables (temperature, pressure, motor status).
· Linked these blocks to Anybus PROFINET I/O addresses.
Step 4: DCS Integration
· Configured Honeywell ModbusTCP client to read process variables from the mapped Modbus registers.
· Validated data points with live trending and alarm testing.
5. Challenges and Solutions
Challenge
Protocol mismatch (PROFINET vs ModbusTCP)
Data type differences (BOOL, INT, REAL vs Modbus registers)
Synchronization issues in polling cycle
Initial network addressing conflicts
Solution
Used Anybus ABC4090-A as a protocol bridge.
Implemented proper scaling and mapping in the Anybus communicator.
Optimized Modbus polling rate and PROFINET update cycle for stable performance.
Used structured IP planning and VLAN segregation.
6. Results Achieved
· Seamless integration achieved without modifying PLC or DCS hardware.
· 100+ process signals successfully transferred in real-time.
· Latency < 200 ms ensured smooth operator monitoring.
· Operators gained centralized visibility of field processes on Honeywell DCS HMI.
· Integration saved ~30% project cost compared to replacing PLC/DCS hardware.
7. Business Impact
· Improved safety and reliability through real-time alarm monitoring.
· Enabled faster decision-making with live data available in the control room.
· Provided a scalable solution, as more PLCs can be connected via additional Anybus gateways.
· Reduced downtime during commissioning, ensuring smooth plant operations.
8. Conclusion
The integration of Anybus ABC4090-A successfully bridged the communication gap between Siemens PROFINET PLCs and Honeywell ModbusTCP DCS, providing a reliable, cost-effective, and scalable communication solution. This case demonstrates how industrial gateways can simplify protocol interoperability in complex automation environments, leading to improved operational efficiency and plant safety.