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PLC/DCS Modbus Interface

Modbus has evolved for several decades to the de facto communications standard for plant-wide communications in the Oil and Gas Market.  Unfortunately several versions of Modbus have developed with unique descriptions and terminology making the Modbus interface more difficult.  It’s not unusual to see the DCS screens developed to display measurement data only.  Unfortunately there are a number of additional diagnostics & data validity checks that may be available from the GC but are rarely included in the DCS screen development.  By providing all the diagnostic AND measurement data to the DCS plant operations personnel can gain confidence in the Process Analyzer readings.  We can assist in providing much needed direction to DCS/PLC programmers to ensure those data validity checks are available and meaningful to operations.

Integrated GC/Flow Computers for energy measurement in Custody Transfer installations

Custody transfer energy measurement requires a Modbus master (usually the flow computer) to perform all flow calculations and act as a Modbus master to the GC. In addition it is also required to perform all offsite communications for both measurement instruments.  We have decades of experience in this area all over the world.  We can bring this experience to both Natural Gas Transmission Companies, Gas Producers AND Large Industrial End-Users that rely on accurate Energy Measurement.  Small errors in energy measurement can have a large financial impact on the bottom line.  We can help ensure that custody transfer energy measurement is accurate and fair for all parties.


Integrated Process Analyzers

In many projects the analytical measurements may require integration of Process GC data with certain other “Trace Gas Process Analyzers.” These other analyzers typically provide H2S/Total Sulfur and H2O analysis at parts per million (PPM) concentrations.  An integrated system can provide full compositional measurement including the trace components in Natural Gas with a common sample conditioning/transport system AND a common software interface (in some cases).  This total gas quality system can report analysis data via Modbus protocol. The benefits are improved accuracy, simplified communications and simplified maintenance/diagnostics as the technician needs to learn one software platform for all analyzers.

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