PAC to a Modern Industrial Application OPC
Look more closely at how a PAC (Programmable Automation Controller) is applied to a modern industrial application using the factory application. The PAC is operating in multiple domains to manage and monitor a production line, a chemical process, a test bench and shipping activities. The PAC must simultaneously manage analog values such as temperatures and pressures, switches, digital on/off states for valves, and indicators; and serial data from inventory tracking and test equipment. At the same time, the PAC is exchanging data with an OLE for Process Control (OPC) server, a Structured Query Language (SQL) database and an operator interface. Handling simultaneously these tasks without need for additional processors, middleware, or gateway is a hallmark of a PAC.
The PAC, office workstation and operator, testing equipment, production line and process actuators and sensors, and barcode reader are connected to a standard 10/100 Mbps Ethernet network installed throughout the facility. In some examples, devices without built in Ethernet connectivity such as temperature sensors are connected to I/O modules on an intermediate Ethernet enabled I/O unit, which is turn communicates with the PAC.
The PAC communicates with remote racks of I/O modules to read or write analog, digital and serial signals using this Ethernet network. The network also links the PAC with as OPC server, a SQL database, and an operator interface. A wireless segment is part of the network, so the PAC can also communicate with the mobile assets like the temporary operator workstations and forklift.
The PAC can control, exchange data and monitor with this wide variety of systems and devices because it uses the same standard network technologies and protocol that they use. This example includes wireless and wired Ethernet networks, IP (Internet protocol), network transport, SQL and OPC. In other control situation, common application level protocols such as Modbus, Simple Network management Protocol (SNMP), Potin to point Protocol (PPP) over a modem could be required. The PAC has the ability to meet these requirements of diverse communication.
S5/S7 OPC Server
The S5/S7 OPC server gives you fast and convenient access to process data in S7-200, S7-311, S7-411 and WinAC controllers, in C7 and M7 units as well as in Pilz, S5, Saia-Burgess or VIPA controllers. The variables are addressed consistently using STEP7 resp. STEP5 semantics. You can use any OPC compliant client application to write and read all input and output data, markers, data blocks, timers and counters in the controllers. Up to 256 controllers can be simultaneously accessed. The program PLC does not need to be modified for communication with the S5/S7 OPC Server.
Access the controller is available via Ethernet of Profibus, USB or via serial communication without or with a modem. CPs from various manufacturers, Netlink PRO and gateways from Softing are supported for Ethernet communication. Appreciation need to be given to the intelligent grouping of write and read requests, the data throughput is optimized so efficiently that Softing’s S5/S7 OPC Server won the best in class award in a practice related performance comparison of seven S7 OPC servers from renowned manufacturers.
The name of OPC space is extremely quick to configure by importing symbolic names from STEP7 projects or Excel files. Existing projects can be exported from software applications like process visualization systems or process control systems to Excel, and are then loaded conveniently into the S5/S7 OPC server.
The OPC server provides a web server for diagnostics and process data visualization. This allows you to display the PLC states and data very quickly on remote or local PCs by simply using any standard web browser. Powerful remote access without DCOM, the Softing OPC Tunnel has already been integrated in the S5/S7 OPC server for safe. Using the OPC Tunnel eliminates the problems associated with DCOM configuration security settings and saves significant time and costs. It only takes few minutes to setup communication for network applications.
OPC or OLE for Process Control is an industry standard for system inter-connectivity. OPC uses COM and DCOM technologies Microsoft to allow a data transfer application with one or more computers through the architecture of TCP / IP.
OPC defines a set of common interface, thus the application will retrieve the data with the same format, regardless of the data from the PLC, DCS, applications or other software. OPC is a communication solution that lives taken, installed and running.
OPC goal is to provide a standard infrastructure for data exchange control process. For example a company has a variety of data such as PLC, DCS, databases, RTU, etc. These data are available through a variety of connections, such as, serial, Ethernet or radio transmitter. While the process control applications can use a variety of operating systems such as UNIX, DOS or VMS.
OPC in this case serves to:
- OPC standardizes process control data communication.
- OPC standardizes the technology, not a product.
- OPC provides true interoperability and scalability.
- OPC can reduce implementation time and costs.
With OPC allows you to visualize, analyze, report through the application of any part with one or more OPC specifications.
By choosing the standard OPC technology, you activate the real interoperability, reduce implementation costs, and make full scalability system for the future.
Author - Arvind Soni