SCADA Integration with SAP using SAP PI – Part 1 - Business case & Systems Involved
Before starting my previous project, I was little sceptic about SCADA (Supervisory Control and Data Acquisition) integration with SAP using PI, whether it is achievable or not. But I had an iota of confidence that this can be done somehow. With the help of SAP's XMII expert Pandiarajan .P and .NET consultant Mahesh Patel, I could successfully implement several interfaces integrating SCADA. Since there is no reference about this topic in SDN, so I thought of putting my experience in words as a series of blogs about the Integration.
1. SCADA Integration with SAP using SAP PI – Part 1 - Business case & Systems Involved.
2. SCADA Integration with SAP using SAP PI – Part 2 – Systems Integration.
3. SCADA Integration with SAP using SAP PI – Part 3 – Interface.
Our client has India’s biggest pipeline connectivity network in Gas distribution, (Downstream – Delivery of Natural Gas through Pipeline & Gas Tankers) which is working under Central Government of India. They have Decentralized SCADA Servers providing by different vendors like INVENSYS and TELVENT. These will get Pressure/Volume/Temperature/GCV/NCV etc values from RTU’s (Remote Terminal Units)/Flow Meters attached across pipelines. Based on the values SCADA will control the GAS flow in Flow Meters remotely. Business case was to fetch these values in to SAP –TSW module and schedule the quantity of the Gas to be delivered on particular day.
Now let me introduce you with the landscape systems involved and brief introduction about them.
- SAP ERP 6.0 EHP 4 TSW Module.
- SAP PI 7.1 EHP 1.
- SCADA with OPC DA Server (2.0) – Decentralized
- OPC Gateways - OPC Clients.
SAP ERP TSW module:
TSW stands for Traders and scheduler workbench. Trader's and Scheduler's Workbench (TSW) provides functions for stock projection and for planning and scheduling bulk shipments using nominations. TSW provides the relevant master data to model the supply chain. The stock projection, planning, and nomination processes enable the scheduler to schedule bulk shipments while taking into account supply, demand, and available transportation.
Processes and Functions
The following planning tools are provided by the TSW application:
- Planning (Replenishment Proposals and Safety/Target Stock Calculation)
- Stock Projection Worksheet (SPW)
- Location Balancing
The following scheduling tools are provided by the TSW application:
- Three-Way Pegging (3WP)
- Berth Planning Board (BPB)
Since Client’s business is to deliver Gas to various dealers, using Pipeline & Gas Tankers, for daily nominations and scheduling the quantity to delivery, this module has been used in the project. [REF: help.sap.com]
SCADA with OPC DA Server (2.0) - Decentralized:
What is SCADA?
SCADA stands for Supervisory Control And Data Acquisition. As the name indicates, it is not a full control system, but rather focuses on the supervisory level. As such, it is a purely software package that is positioned on top of hardware to which it is interfaced, in general via Programmable Logic Controllers (PLCs), or other commercial hardware modules. SCADA systems are used not only in most industrial processes: e.g. steel making, power generation (conventional and nuclear) and distribution, chemistry, but also in some experimental facilities such as nuclear fusion. SCADA systems used to run on DOS, VMS and UNIX; in recent years all SCADA vendors have moved to NT.
SCADA systems are widely used in industry for Supervisory Control and Data Acquisition of industrial processes. Companies that are members of standardisation committees (e.g. OPC, OLE for Process Control) and are thus setting the trends in matters of IT technologies generally develop these systems. SCADA Server’s which our client own was provided by following vendors:
There were multiple instances of these SCADA servers which are decentralized. But servers get synchronized with real time data on periodical intervals.
How to communicate with SCADA?
These SCADA systems include OPC (OLE for Process Control) Servers inside, other than its own Data Sources. OPC Servers are software applications (drivers) that comply with one or more OPC specifications as defined by the OPC Foundation. OPC Servers communicate natively with one or more Data Sources on one side and with OPC Clients on the other. In an OPC Client / OPC Server Architecture, the OPC Server is a Slave while the OPC Client is the Master.
Versions of OPC Servers released so far:
Data Format in SCADA:
Data in SCADA is available in the form of TAG’s, something like:
For each tag corresponding value will be updated to SCADA database by the RTU’s (Remote Terminal Units) connected to Gas Pipeline. Based on which SCADA will control the flow of Gas through Flow Meters attached to Gas Pipeline. OPC Client machines will request these tag values by specifying the tag name. Client machines got the facility to subscribe the functionality to get updated information of tag values, every second or even shorter time interval.
For further information on OPC Server please refer to MatrikonOPC.com
OPC Gateways (OPC Clients)
OPC Gateways systems are Client machines that will communicate to OPC Server in SCADA system. These Gateway systems with Windows Operating System and ISS installed & running. Communication between the OPC Client and OPC Server is bi-directional meaning the OPC Clients can read from and write to OPC Servers. Classic OPC Servers utilize the Microsoft Windows’ COM/DCOM infrastructure as a means of exchanging data. This means these OPC Servers must run on the Microsoft Windows operating system. An OPC Server can support communications with multiple OPC Clients simultaneously. But latest releases of OPC Servers supports HTTP Communications so Web Service are provided by OPC Servers can be directly consumed by client applications like SAP PI or ERP directly.
OPC Client – OPC Server Communication
These are all the systems and brief information about them.
Let us discuss about the Architectural connectivity that we followed in our Systems Integration in my next blog. I hope this blog series helps you get an idea on integration between SCADA and SAP.