Emerson ROC800 vs ABB Totalflow — Flow Computer Comparison for Gas Measurement

Quick Answer

Both are industry-standard flow computers trusted for custody transfer gas measurement. Emerson ROC800 offers modular I/O expansion, ROC Protocol for integrated SCADA communication, and wider general-purpose automation capability beyond flow measurement. ABB Totalflow provides specialized high-accuracy gas measurement with extensive AGA calculation options, strong chart recorder integration, and deep expertise in natural gas gathering and transmission applications.

AGA Flow Calculations

Both platforms support the standard AGA calculation methods used in North American gas measurement: AGA-3 (orifice plate), AGA-7 (turbine meter), AGA-8 (gas compressibility), AGA-9 (ultrasonic meter), and AGA-11 (Coriolis meter). Both are certified for custody transfer measurement and produce audit-quality measurement records.

ABB Totalflow has historically been considered the benchmark for gas measurement accuracy and has a deeper specialization in gas chromatograph integration and gas quality calculations. ROC800 provides equivalent AGA calculation capability with broader general-purpose automation features.

I/O and Expansion

ROC800 uses a modular I/O architecture with hot-swappable modules in a rack configuration. This allows customizing I/O to match application requirements — from a simple single-run measurement station to a complex multi-run facility with control outputs. The modular approach simplifies maintenance and future expansion.

ABB Totalflow uses a more compact fixed-I/O approach with expansion through external modules. The Totalflow G4 and G5 platforms provide sufficient I/O for typical gas measurement applications but offer less expansion flexibility than the ROC800 for complex control applications.

Programming and Configuration

ROC800 is configured using Emerson's ROCLINK 800 software and programmed with FloBoss user programs for custom logic. ROC Protocol provides native integration with Emerson's SCADA products and is well supported by third-party SCADA platforms.

ABB Totalflow is configured using PCCU32 (Portable Calibration and Configuration Utility). PCCU32 provides comprehensive access to all flow calculation parameters, diagnostic data, and configuration settings. Totalflow uses a proprietary application programming interface for custom logic.

Communication and SCADA Integration

ROC800 supports Modbus TCP/RTU, ROC Protocol, DNP3, and HART pass-through for connected transmitters. ROC Protocol provides efficient data transfer with Emerson SCADA systems but is also supported by many third-party SCADA platforms.

ABB Totalflow supports Modbus TCP/RTU and DNP3. ABB has invested in modern communication options including cellular and satellite connectivity. Totalflow integrates with ABB's AbilityTM Symphony Plus platform for enterprise-level SCADA and historian.

Best Fit by Use Case

• Single-run measurement station — Either platform performs well. Choose based on installed base.
• Multi-run measurement and control — ROC800. Modular I/O and general-purpose automation capability.
• Gas gathering with GC integration — ABB Totalflow. Deeper gas chromatograph integration and gas quality calculations.
• Existing Emerson infrastructure — ROC800. Consistent with ROC Protocol ecosystem.
• Existing ABB/Totalflow infrastructure — ABB Totalflow. Consistency and configuration tool familiarity.

Summary Comparison