Automation Software: Process automation modelling tool makes the grade
By Jeremy Pollard
One of the benefits of belonging to an Internet mailing list is that it can be a great source of anecdotal information. I recently visited an industrial controls website, where I got in touch with users of ControlDraw, a process-modeling tool manufactured by Control Draw Ltd. in the United Kingdom for process control engineers.
Francis Lovering is the software’s author. Lovering started designing his “labour of love” after deciding there were no satisfactory tools out there for process control engineers involved in process modeling. ControlDraw allows you to manage documents and data for the lifecycle of a system by providing integrated drawing, text and data handling for the design, specification, simulation and documentation of process control systems.
Kurt Dyck is a controls design engineer for a coffee company in Burnaby, B.C. He uses ControlDraw to generate process and instrumentation drawings (P&ID) based on a sequence of operations (SOO) outlined by his process engineers. Dyck generates all of the documentation from ControlDraw required to build a new process, so that the automation guys can create the hardware and software to meet his specifications. He says he finds that ControlDraw allows him to systematically piece together the new process in an object-oriented fashion, which allow his work process to flow more easily. Although he doesn’t use the full potential of ControlDraw, he finds the core functions of the product to be invaluable for his responsibilities, he says.
After receiving the SOO from the process definition team, he would import those definitions into ControlDraw. The next step would be to link the P&ID to the SOO using objects in the database. This creates the beginning of a process model. This model supports the actions of the batch specification SP88, as well as various programming languages for graphical representation and simulation.
So I sat down with the software to see what Kurt was talking about.
When you open a new project, it can be a bit intimidating. By selecting the template “start” mode, ControlDraw adds 27 to 37 process-related pages that you can use for your process definition depending on your reliance on the SP88 specification.
Each page is pre-defined as a class. These classes determine what the data on the page is, and what it means. Those classes include Process Cell, Unit, Equipment Module, Recipe Procedure, Operation and Phase. The layout of the class gives you a start towards completion of the process diagrams. The process cell is the first page displayed. This is where you would graphically define the process.
ControlDraw provides a roadmap describing what to do next. As always, I hit the help file. I found the help file a little disorganized, and got lost fairly quickly.
Imagine a small tank filling or mixing process. This is the process. On the P&ID drawing, the process inputs and outputs are defined as raw materials and packaged product. The process cell (defined by the Tag UN01 on Drawing A) defines the rest. Underneath the UN01, there would be additional information, such as timing, sequence and fault control, which would continue to define this process.
Once the process blocks are on the sheet, and connected, the graphic capabilities are very broad, and features, such as connecting lines moving with objects, have been designed into the editor. ControlDraw does a good job of creating object graphics and linking those objects together.
The graphics can be function-block like or SFC (as found in the programming specification IEC-61131) or a true representation of the process (P&ID)–the choice is yours.
One really cool feature is ControlDraw’s unit control matrices. You can create a table showing how the equipment modules interact and react to process conditions. In my example, the unit class (the tank filling part of the process) contains two equipment modules. One module is for the raw material feed, and the other is for the finished product transfer. The matrix for the equipment modules is pretty simple, but when you expand the modules to show the background control elements, the control matrix for the components can be very helpful for understanding how the components interact with each other and the steps in the process. Regardless of code, this is the way the process is designed, so using it as a training tool, a troubleshooting tool, or a primary design platform, can be valuable.
The software also supports the generation of many lists, such as IO Lists, Alarm lists and parameter lists, these being generated from the model itself, which is a Microsoft Access database.
This product is very deep and is an excellent process design and simulation tool. Be prepared to spend a significant amount of time on the learning curve, but users can call or email Lovering for technical support and guidance when they need it.
You can reach Jeremy Pollard at firstname.lastname@example.org.
Version: Version 2
Vendor: Control Draw Ltd., SouthSea, United Kingdom (www.controldraw.co.uk)
Application: Process Automation Modelling System