PiLims is an OPC client software product that allows an operator, technician or engineer to enter data on a Windows Server-based computer and then pass the data into a DCS or PLC. In a manufacturing process or a chemical plant, there are many needs where data entered by a human being must be downloaded into the DCS. In many cases, data entry directly into the DCS or PLC is not possible or may be prohibited by control room or laboratory policies because of security reasons. Entering the data into a Windows server computer is safer and may be also recommended especially when there are some other specific needs such as printing of labels, custom data validation and other special needs. Following is a simple illustration of PiLims:
A few sample screen shots illustrating PiLims configuration process and overall details are shown
Data from a laboratory may need to be entered in a special custom computer screen from which it needs to be transferred into a DCS or PLC. PiLims is the software product for this need. PiLims can be created with a custom user interface specifying the names of the laboratory samples and tag names. After each laboratory value is available, both the time stamp and the laboratory sample value can be entered into the computer screen. After validation and release by the user, the data is then written out into the DCS or PLC.Configuration of PiLims
Configuration of PiLims is remarkably simple. The user configures an ASCII file to specify the lab tags and details such as tag description and names. Or alternately, data may be written to an Excel file that is updated periodically by another application written in any language â€“ VB, C++ or even Access. Such an external application can update the Excel file which is the input file to PiLims. PiLims then sends the data into the DCS.
PiLims provides a quick and easy method to configure as many as 2000 tags conveniently. Testing with an OPC Simulation server
PiLims provides the capability to test easily with any standard OPC simulation server. This capability is useful for testing and also for training purposes.
Technical Help and Support
For technical help and additional details on PiLims, please contact PiControl Solutions Company via email at info@PiControlSolutions.com
Pitops-PID decomposes the total controller contribution into the individual proportional, integral and derivative contributions and plots them individually as a function of the time axis. This provides diagnostics which are useful for critical advanced control loops, especially slow loops with long process dead time where use of derivative can significantly improve controller performance.
The optimal tuning of critical loops must take into account the nature of the process, how fast the control valve can be allowed to move, nature of known and unknown disturbances and other custom issues unique to the loop. Pitops-PID allows you to configure a custom simulation quickly and easily.
Figure 2 shows a simulation comprising of superimposed disturbances like those seen in the real process. After configuring the disturbances, Pitops-PID optimizes the tuning parameters based on the custom simulation, taking into account the control needs of the loop, which include the following:
1. Typical setpoint changes
2. Typical disturbances
3. Output rate of change consideration
4. Any other custom needs specific to the PID loop
5. Optimize PID tuning to handle control valve stiction or deadband
Most other products optimize tuning based on heuristics and error criteria; in contrast, Pitops-PID optimizes based on the precise (custom) process characteristics and control objectives.
Pitops-PID provides cascade PID simulation and sequential optimization capability to optimize both slave and cascade controllers – see Figure 3. A single, easy-to-use master screen allows you to specify most parameters.
You can specify slow loops, GC analyzer sample time delay and special transforms like natural logarithms, square and square root to linearize commonly known non-linear processes. These transformations are used for constraint control for distillation column delta pressure to infer column flooding limits and also for tighter control of tall superfractionators where the distillation purities behave non-linearly.
Pitops-PID provides calculation procedures and commissioning guidelines to design and implement feedforward controllers.
Most other competitor software products run in the discrete (Z) domain. In contrast, Pitops-PID runs completely in the time domain which is easier to understand by people of all skills and experience levels.
Pitops provides powerful, easy to use feedforward simulation module. Many skilled control engineers have admitted that they began to truly appreciate some important aspects of feedforward control design only after being exposed to Pitops-PID. Pitops-PID automatically optimizes controller parameters for a closed-loop simulation for a real-plant case configured with a disturbance and feedforward model precisely matching the process dynamics. The feedforward trends in Pitops-PID are shown in Figure 4.
Powerful model-based control schemes can be built in the DCS using Pitops-PID suite of model-based controller design, see Figure 5 for an illustration.
Using regressed, empirical, semi-empirical or rigorous chemical engineering models, effective model-based dynamic controllers can be easily implemented. The procedures show how to build controllers at a fractional cost and effort compared to other options.
Pitops-PID is the only tool that any control engineer will ever need in the control room. All simulations can be built very easily in a matter of minutes. This ease of use is unmatched by any other competitor software. Both new and skilled engineers and also DCS technicians/operators have successfully used Pitops-PID with ease and confidence.
Pitops optimizes PID tuning parameters to improve control action amidts control valve problems such as stiction and deadband. For control valves with stiction or deadband, Pitops will move the controller settings in the direction of increased proportional and derivative action and reduced integral action.