Product
ModBlock for Digital Probe Integration
Digital probes provide many advantages over conventional style analog probes.
Advantages can include:
- A rich set of diagnostic data to determine probe operating parameters. This data may be used for device tracking, preventative maintenance, and determination of probe status.
- Seamless integration into a plant wide MES (Manufacturing Execution System)
- Simplified calibration to manufacturer specification.
- Improved accuracy
- Enhanced resistance to electrical interference
Historically, probe interface to the overall control system (SCADA, DCS, PLC, PC based controllers) via analog signalling (4-20mA or 0-5V). In recent years, most manufacturers have offered a digital solution, however the interface to these control systems have not been considered.
What is ModBlock?
ModBlock is a full digital solution for interfacing Hamilton ARC style probes to a DeltaV control system.
The ModBlock solution includes probes, cables, digital transmitter (ModBlock device), DeltaV serial landing module, and DeltaV graphics to support full digital integration with complete visibility to the entire probe data set.
Technical Overview
ModBlock acts as a ModBus RTU data collector for dual Hamilton probes. Currently pH and DO probes are supported, but in the near future, the full portfolio of Hamilton probes will be supported.
Although all Hamilton ARC probes support Modbus RTU, the data mapping is not easily managed by Emerson DeltaV Modbus RTU master implementation. The reason why is the Hamilton modbus map is fragmented, and each register set mixes data of different type. DeltaV modbus implementation requires a Modbus operation to act on a contiguous set of registers with a consistent type and direction. For example, a multiple register read requires that all registers be contiguous, of the same type (Integer or Floating Point), and direction (read or write). When a slave device has data that is fragmented, this can require many small register sets (data sets) and associated operations resulting in excessive resource usage (both DST and serial port hardware in the case of DeltaV) and segment performance issues.
ModBlock implements 2 features that alleviate any resource usage issues while still allowing full access to the entire probe data set. These features are:
- Data aggregation – ModBlock reads data continuously from both probes, and arranges the data in a manner compatible with DeltaV requirements
- Data multiplexing – ModBlock does not demand a DeltaV register per probe parameter. Instead, lower priority data that is not used for control is slowly periodically collected in parts as opposed to each module or modbus segment cycle.
The end result of the above is full access to all probe parameters with total 2 DST consumption.
ModBlock Configuration
Every effort was made to simplify Hamilton probe integration. To this end, both the DeltaV and port communication setup is largely “plug & play”. There is no complicated programming or switches to set up, simply plug in the probes and box, and click a button to initiate communications setup. All details are handled by ModBlock.
Why should I use ModBlock?
ModBlock excels at providing a unified, consistent, fully digital solution for interfacing Hamilton ARC style probes into your DeltaV control system. Traditionally, handling different probe types meant conditioning and measuring vastly different analog signals. For example, a pH probe signal level is mV, and DO probe is nA. These each require specialized analog signal handling, and suitable transmitters are typically not interchangeable.
ARC Probes in contrast have a consistent interface. It is only the data that must be handled differently. Each ModBlock port is “agnostic” in that any ARC style probe will be supported allowing for upmost flexibility.
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ModBlock Introduction Videos