Implementation of Isa S88.01 Standard Into an Automated Process

Scientific Bulletin of the Electrical Engineering Faculty – Year 13 No.4 (24) ISSN 1843-6188

IMPLEMENTATION OF ISA S88.01 STANDARD INTO AN AUTOMATED PROCESS

G. OPREA Valahia University of Targoviste, Doctoral School of Engineering Science - Electrical Engineering, 35 Stancu Ion Street, 130105, Târgovişte, ROMANIA E-mail: [email protected]

Abstract. S88 Batch Control Standard has been developed that causes equipment to do the things necessary to make under the auspices of the ISA (the Instrumentation, Systems, a product – no matter how that control is achieved. and Automation Society) and is the appropriate Standard to Manual control is best or quite appropriate in many apply in many Batch Process Control or Automation projects. cases; automatic control is better in others. S88 works The S88 standard enables clear and concise transfer of with either case, or both. It is based on the premise that information between different disciplines, specifically the Process Engineer and the Automation Engineer. The whether a function is controlled manually or standard breaks down 'process areas' into 'process cells', automatically it is the function that is important. This is 'process units', 'equipment modules' and finally 'phases'. particularly important in modern manufacturing Using these smaller 'blocks' the URS (User Requirement approaches where there is usually the need for smooth Specification), FDS (Functional Design Specification) and integration of manual and automatic control activities. ultimately the final control software, are constructed in a Few plants actually run all night with the lights out and logical 'easy to follow' way. people are a long way from being obsolete.

Keywords: process, areas, cells, units, equipment modules, phases. 2. CONTROL PHILOSOPHY AND S88 STRUCTURE

1. INTRODUCTION From the side of the control system the complete plant is The ISA1-88.01-1995 Batch Control standard has had a divided up into single control modules, phases and major impact on the way batch process automation is recipes. With these control modules and phases the done today. It has influenced everything from the way complete plant with all its instrumentation is defined. control systems are built to the way project requirements This structure follows the S88.01 architecture [3]. are written and has simplified and reduced the cost of batch control automation along the way [1]. At any time the state of the complete plant with all the equipment will be visualized on the various PC-screens. S88 defines Recipes, which describe products and how Motors, valves, limit switches will change colours those products are produced. Recipe procedures reside depending on their state. The analogue values are on a PC, while the programming code running the displayed as a number and in a trend. production equipment resides in the PLC (programmable logic controller) or DCS (distributed control system) 2.1 Control modules residing within the equipment [2]. A control module is controlling a single equipment part. When it comes time to make a product, the The available control modules are: valves (On/Off manufacturing requirements defined by the recipe and its valves or proportional valves), motors (fix speed and procedure are linked to the required equipment. The variable speed), analogue sensors (temperature, pressure, recipe phase within the PC batch server communicates flow, weight, etc.), digital sensors (proximity switches, with the equipment phases via a set of protocols held in safety switches, etc.), PID control loop (for temperature, the PC. These protocols define the states the equipment flow, pressure, etc.) and counters (for dosing via flow may function in, e.g. idle, active, pause, stop etc, and the meters) [4]. possible transitions between states. A Phase Logic Interface (PLI) resides in the PLC or DCS system to On the SCADA system each of these control modules enforce these transition protocols and communicate back will be displayed by a corresponding symbol. For each and forth with the PC. The fundamental difference control module a faceplate can be opened for additional between traditional control and control as outlined in information. This faceplate gives also the possibility to S88 is that S88 adds control of procedure and a level of adjust parameters such as monitoring times, PID loop coordination control necessary to keep multiple parameters, thresholds, etc. A service mode for procedures sorted out. The concepts that are spelled out authorised users is available to operate an actor in a in terms of a batch manufacturing environment are service mode or set substitute values for a sensor. consistent regardless of whether the control is provided manually or automatically. It treats control as a function In the next example (Figure 1), is described the specifications of an equipment module control.

ISSN 1843-6188 Scientific Bulletin of the Electrical Engineering Faculty – Year 13 No.4 (24)

uses the vacuum pump, plus a couple of valves and the pressure transmitter [5].

The phases can be operated in manual and automatic mode. The manual mode can be used for the commissioning of the single phases as well as for trouble shooting. In manual mode the operator is responsible for the entering of the correct set points and for the starting and stopping at the correct time.

A production is normally carried out in automatic mode, where the set points for the phases and the sequencing are specified in the control recipes.

Some of the mentioned phases are static, meaning that they need to be switched off. In this case the start and a stop phase are available. Other phases are non static; they switch off automatically after e.g. having dosed the required quantity.

Common to all phases is that the phase will be paused when a control module of an equipment part which is used by the phase has created an error. E.g. a valve does not reach the requested position, motor trips out, fault on a sensor, etc. A phase in pause will automatically deactivate all equipment parts which are used by this phase. Meaning the valves will be closed and the motors will stop. A paused phase may also pause another phase. This is the case, when the running signal from one phase is one of the permissive for another phase.

2.3 Phase control panels

Phase control panels are boxes with the phase reference number followed by the phase description. They are the operational steps through which the production process goes.

P100 P100 P100 P100 Heating Heating Heating Heating loop loop loop loop

Figure 2. Sample phase control panels

The panels will change color, (Figure 2) depending on the status of the phase it refers to: Figure 1. Equipment module control specifications - Clear Phase not active; - Green Phase active; Inputs are indicated in a prescribed format on top of the - Salmon Phase currently paused; picture, outputs are shown on the bottom and in the - Red Phase stopped – either in alarm or by operator central part the processing which is necessary is action. described. Any other equipment module control should be described in the same manner. By selecting the phase control panel a pop-up (Figure 3) will appear on screen which contains all the relevant data 2.2 Phases for that phase. It also contains the manual operator control soft buttons for that phase. The information and A phase is a combination of some of the control available functions within a phase control panel vary modules, which has to be operated together to achieve a from phase to phase. In the phase control panel pop-up specified result. The phase pressure control for example section all available parameters are listed. The section is split into to 3 parts:

Scientific Bulletin of the Electrical Engineering Faculty – Year 13 No.4 (24) ISSN 1843-6188

- Set points: These parameters, such as the required pressure or temperature are typically changed more frequently. They can be used in a recipe at different stages of the batch with different values. If a phase is running in manual mode the set points for the manual mode will be used. If a phase is running in automatic mode, the set points from the recipe will be used.

- Plant specific data: These parameters cannot be changed from recipe to recipe. The parameters can only be changed by persons Figure 4. Phases flow chart with a special access level. For each of the 3 main process steps, process 1, process - Actual values: 2 and process 3, individual control recipes are defined. These parameters cannot be changed; they display the These recipes contain all the required information to actual values for different variables. control the process. This includes times, speeds, product ingredients, temperatures, weights and so on. The control system will handle the download of the correct control recipes according to the master recipe at the right time into the several process units.

2.6 Master recipes

A master recipe contains the control recipes for the different process steps. For each final product a master recipes needs to be defined. To start a production of a specified product the corresponding master recipe has to be loaded. The system then will download the correlated control recipes for the 3 process steps into the different process units.

3. PLANT CONTROL SYSTEM AND OPERATOR INTERFACE

S88 defines hierarchical recipe management and process segmentation frameworks, which separate products from the processes that make them. The standard enables re- Figure 3. Phase control panel pop-up and ,,actual” popup use and flexibility of equipment and software and provides a structure for coordinating and integrating 2.4 Transition condition recipe-related information across the traditional ERP, MES and control domains. In case the plant is operated in automatic mode by running a recipe, the system steps on to the next phase in The control system downloads the control recipes at the the sequence when this transition condition for the required time according to a master recipe. A master running phase is fulfilled [6]. recipe will exist for each of the final products to be produced. Editing of the recipes can only be carried out For example when the required amount is dosed, the by authorized persons via password protection. To start required runtime is elapsed, the value for temperature or production of a specified product the corresponding pressure is reached, etc. master recipe has to be loaded. The operator selects this master recipe as an order from the order control screen 2.5 Control Recipes on the SCADA system.

A combination of the above mentioned phases, put When the order is started the system will download the together in form of a flow chart (Figure 4). A recipe required control recipes for the 3 process steps into the consists of information about the set points for the different process units. The operator then starts the individual phases as well as about the sequence in which available batches for this order. The system will then the individual phases has to be carried out [7]. start processing the batch.

ISSN 1843-6188 Scientific Bulletin of the Electrical Engineering Faculty – Year 13 No.4 (24)

3.1 Plant control - The visualization of the equipment; - The overview of the Batch process and status; The complete control system consists of 3 main - The alarm and message handling and recording; functional elements: the Process control system, the SCADA system and the PLC [8]. - User interface for manual intervention. All the screens can be used by means of a mouse/touch 3.1.1. The process control system screen or keyboard. Each site will locate the SCADA screens appropriately so for information please refer to The process control system is responsible for optimizing your sites local appendix for details. Access to all the different process phases. It allows the creation of screens is possible from any of the SCADA units recipes in form of a flow chart. These recipes are then however password protection is applied to certain used to control the individual phases required to make up maintenance and higher level functions such as batch the desired product [9], [10]. and recipe modification.

The required number of batches is calculated 3.1.3 PLC automatically. This calculation is done every minute and takes into account any amounts already produced and the The PLC (Programmable Logic Controller) is from the remaining material in the plant. Siemens S7-400 range of industrial automation controllers. The PLC monitors all the signals from the sensors and controls all the plants actuators (valves, 3.1.2. SCADA System switches motors etc). Based on the algorithms within the

program it takes the recipe, which it receives from the The SCADA (Supervisory Control and Data process control system and controls all the single control Acquisition) system is the part of the control system modules, all the phases and the sequencing of the responsible for giving the operators the visualization of recipes. the equipment and processes (Figure 5). This is achieved through the different screens displayed on the HMI The PLC continuously communicates with the SCADA (Human Machine Interface – the touch screen PCs) [11]. system and the Process control system to read commands

and send status information. The SCADA screens show information which has been communicated via the PLC [12].

3.2 Communication with ERP system

The production network is separated from the plant network where the ERP system (SAP) is located. The whole data transfer between the control system and ERP will be managed by the PLC (Figure 6). Therefore the PLC has for each communication partner a separate network module at share the same memory to read/write each other’s parts of data blocks that need to be defined.

Figure 5. SCADA screenshot

From these SCADA screens the operator can monitor and control the different processes. The errors or warnings from the plant and process are displayed on the SCADA screens and the system also logs all alarms and messages for future reference. This is useful in the event that several faults occur at once, as it saves the operator Figure 6. Communication between networks having to make notes of the alarms for the maintenance teams. The system also logs all events and analogue 3.3 Production orders values from the plant such as temperatures. These analogue values can then be displayed as a graph. This ERP system will transfer all orders that are planned to be graph can be viewed in real time as well as looking at fulfilled in a reasonable plan time range. An order from historic data. The main features of this SCADA system ERP contains very compressed information. This are: information contains following data: production line, set

Scientific Bulletin of the Electrical Engineering Faculty – Year 13 No.4 (24) ISSN 1843-6188 amount of product [boxes], amount per boxes [kg], best 5. REFERENCES before offset, planed start-up date and time, SKU (stock keeping unit). [1] Introduction to S88-For the improvement of the

design of batch systems, Japan Batch Forum, 4. CONCLUSION jbf.pse143.org/files/S88e.pdf.

[2] ISA Organization - ISA88 Batch Standards and The fundamental difference between traditional control User Resources, 2011 the 4th Edition. and control as outlined in S88 is that S88 adds control of [3] Joseph Hanlon, Robert Kelsey, Hallie Forcinio procedure and a level of coordination control necessary Handbook of Package Engineering, 3th edition. to keep multiple procedures sorted out. The concepts that [4] ISA Organization - ANSI/ISA-88.00.01-2010 Batch are spelled out in terms of a batch manufacturing Control Part 1: Models and Terminology. environment are consistent regardless of whether the [5] Renee Robbins, - New resources for now, 2007, control is provided manually or automatically [13]. Control Engineering;Dec2006, Vol. 53 Issue 12, p2. [6] James R. Koelsch - International Standards Boost S88 isolates recipes from equipment. When the software Efficency, Automation World, January 2005. (S88-compliant or otherwise) that defines a product [7] ISA Organization - ANSI/ISA-88.00.03-2003 Batch (recipe procedure) and the software to run equipment Control Part 3: General and site recipe models and (phase logic) are in the same device (such as a PLC or representation. DCS), the two different sets of code eventually become [8] W. Covanich , D. McFarlane and A. M. Farid indistinguishable and, in some cases, inseparable. This "Guidelines for evaluating the ease of makes recipe and equipment control difficult, if not reconfiguration of manufacturing systems", impossible, to maintain. Every additional ingredient and Proc.6th IEEE Int. Conf. Ind. Inf., 2008, pp.1214 - process improvement can lead to lengthy and error-prone 1219. software changes. Documenting and validating such a [9] ISA Organization - ANSI/ISA-88.00.04-2006 Batch system is also extremely difficult, and doubly so if not Control Part 4: Batch Production Records. S88-compliant. [10] K. Thramboulidis, S. Sierla, N.Papakonstantinou and K. Koskinen, An IEC 61499 Based Approach And however, S88 is important for several reasons but is for Distributed batch Process Control, Proc. of the 5 best known because it has been proven to deliver th IEEE International Conference on Industrial measurable benefits when properly applied to define and Informatics (INDIN'07), Vienna, Austria, Vol. 1 pp. implement batch process automation. Those and many 177-182, 2007. other benefits are the subject of this and following [11] ISA Organization - ANSI/ISA-88.00.02-2001 Batch sections. Naturally all benefits come with some cost and Control Part 2: Data structures and guidelines for the use of S88 is no exception. The primary cost in the languages. case of S88 is the time that needs to be dedicated to [12] OMAC Packaging Workgroups. learning what the standard teaches and how to use it http://test.omac.org/content/packaging-workgroup [14], [15]. [13] Rockwell Automation - Benefits of Manufacturing Control; https://www.plantservices.com/ In the case of a production manager, the time required to [14] Pete Lawton - An Examination of the Benefits of a start participating may be no more than an hour or two. Single Control Platform in Packaging Machinery, Others, who must learn the technology as well as the ISA Denver Section. principles, will spend more time, perhaps a week or [15] Bucur I. Ion, Cupcea Nicolae, Ştefǎnescu Costin, more. The time spent is definitely worth the effort, but it Popescu Cornel, Surpǎţeanu Adrian, Boiangiu is necessary to invest that time in order to derive the Costin-Anton, "Signal Driven Partitioning Large benefits that are there for the taking. It can serve as a Circuits," The 20-th DAAAM World Symposium, common language for engineering and operations Austria Center Vienna (ACV), 25-28th Nov. 2009, management to better understand and manage pp.1121-1122. manufacturing automation requirements and benefits. It is an internally consistent standard for automation that reduces the engineering cost for automation. It is a powerful tool for operations managers and engineers with many benefits, but there is a learning curve: short for managers; longer for engineers - a low risk investment with an immediate payback. This can be witnessed from its extensive application in the field.