GxP-Blog

Due to the different standards and products in the world of automation, pharmaceutical companies are forced to establish a standard. The issue of interfaces and how the desired and required data get from A to B is a high priority.

There is a wide variety of solutions and systems for automating processes. Thus, when you’re planning and implementing automation systems, you must take care to minimize the range of interfaces. This reduces the planning risk as well as the risks of faulty data transfer and bottlenecks.

Each individual level of automation should be precisely analyzed. The signal flow from the field to the MES¹ via the individual levels must be tested. When sensors and actuators are used, the life cycle (calibration and maintenance intervals) must also be reviewed. The use and selection of the required bus technologies at the individual levels must be reviewed with regard to data volume, speed and the environment in which they are used. When MES and ERP² systems are used, the requirements of these systems must be included from the very beginning of the planning phase for process automation. It is very difficult and costs extra to connect these systems to the automation structure at a later point in time. Particularly for batch processes, detailed coordination of the data flow and the processing in the individual systems from ERP to MES via PCS³ must be precisely specified.

The signals from the field level can be recorded using analog or digital technology. When the signals are recorded with analog technology, 4–20 mA signals should be used. This ensures that any wire breaks in the sensor system will be detected. However, in analog technology the entire measuring chain from the sensor to the analytical unit to PLC⁴ is subject to drift, which can lead to deviations in the measured values at the analysis or storage site. The signals from the field level can also be digitally recorded via field bus systems such as Profibus PA⁵ or Foundation Fieldbus. When signals are recorded this way, the values are transmitted digitally to the control system and are not subject to drift. However, the planning for these bus systems is considerably more complex.

In the meantime, the field of measuring technology is undergoing a transformation as well. The sensor system now transmits the measuring signal digitally, not in analog form, to the connected measuring transducer. The calibration data and ID are stored directly in the sensor. This largely prevents erroneous input from reaching the measuring transducer as well as faulty connections.

As a rule, a uniform system architecture from one manufacturer should be planned or available for process control. This ensures that the data exchange within this level from controller to controller proceeds in compliance with the protocol of the manufacturer. The data bottleneck (gateway) that appears when controllers from two different manufacturers with different protocols are connected is thus avoided.

In the areas of process control and visualization, there are solutions available from various manufacturers. PC-based systems offer a standardized interface for data exchange (OPC). The OPC interface transmits data via computers connected to TCP/IP. The OPC server gets the process data from the connected PLC and makes them available as OPC objects. To be able to fetch the data from the relevant controller, the OPC server must understand the respective language of the connected PLC (e.g. S7 protocol, Siemens). With the OPC UA (unified architecture) specification, all previous specifications (OPC DA, OPC HDA, OPC A/E, DCOM) should be implemented independently.

In the meantime, ERP systems are used in many manufacturing companies. The primary tasks of this system include planning material requirements as well as production planning and control. When such systems are deployed, precise planning of the interfaces and the data flow to the lower-level systems is indispensable. The ERP and MES systems are historically part of IT, while the PCS, SCADA and PLC systems are part of the world of automation. Due to the different areas and specialty classifications, it is very important to specify the shared interfaces precisely.

In project management, it is essential that both parties – from the IT environment and from the automation environment – work towards the project goal together and coordinate with each other regularly. The connection of the ERP system to production generally ensues via a manufacturing execution system (MES) as an organizational link. The MES collects the process data from the subordinate SCADA level and makes it available to the ERP system. The connection of ERP to MES is often made via remote function call RFC⁷ or RPC⁸. The process data from SCADA, which can come from different process control systems, are continuously transmitted to MES, e.g. via SQL⁹. The MES performs the allocation of the data to the batches and job data. All of the data recorded by the MES are thus available in the IT environment for evaluations and analyses. Detailed interface programming is frequently required for the automation of batch processes and the analysis of batch information. There are currently no uniform specifications available. A production order in MES can result in the processing of multiple orders on the PCS side. The User Association of Automation Technology in Process Industries (Namur) is working on producing and establishing a batch interface specification.

Chemgineering will be happy to support you in the planning and implementation of various automation solutions tailored to your specific needs. Thanks to our many years of experience in automation technology for the pharmaceutical environment and the excellent collaboration with system suppliers, we guarantee that our customers will consistently enjoy the latest technology.

¹ MES = Manufacturing Execution System
² ERP = Enterprise Resource Planning
³ PCS = Process Control System
⁴ PLC = Programmable Logic Controllers
⁵ PA = Process Automation
⁶ SCADA = Supervisory Control and Data Acquisition
⁷ RFC = Remote Function Call, SAP
⁸ RPC = Remote Procedure Call
⁹ SQL = Relational Database Management System