Programmable controllers

A CIP system includes pipelines, interconnected with valves to direct fluid to appropriate locations, and the control circuit, which consists of interlines to control the valves that direct the cleaning solutions and water through the lines, and air lines which control and move the valves. A programmer controls the timing and the air flow to the valves on a set schedule. The 3A Standards for CIP components, equipment, and installation have been developed. A simple CIP system circuit is shown in Figure 11. 

EMEC 1988a. Programmable Controllers. Eoss Prevention Data Sheet No.5-27. Eactory Mutual Engineering Corporation, Norwood, MA. 

The strict requirements placed on the quality of the regenerator pressure control system necessitate complex control strategies that can only be achieved using modern freely programmable control systems, while the short actuating times of the control valves require controllers with ultrafast response. 

The complexity and reduced time constants of modern processes imply the adoption of high performance programmable controllers. This requires not only higher processing speed but also more advanced control algorithms that can optimize the process operation in real time. 

An EMCS is usually a network of microprocessor-based programmable controllers with varying levels of... 

It should be able to communicate with other kinds of systems found in manufacturing environments (e.g., plant MIS computers and programmable controllers). 

The U.S. Army Defense Ammunition Center and School is employing the use of intrinsically safe electrical circuits in equipment designed to demilitarize and renovate munitions - from small arms to large projectiles. This is accomplished by using pneumatics and hydraulics to provide the power, while using position switches and solenoid valves linked to programmable controllers to direct the total machine process. 

If you have measured resolution of a few key components of a mixture under a small number of conditions, commercial software is available to optimize conditions (such as temperature and pressure programming) for the best separation.19 Just over the horizon, greatly improved separations will be possible by coupling two different columns in series with programmable control of the flow rates (pressure) in each column during the separation.20... 

RDM Reserve data aquisition module. CM control module ROM Reserve control module. PLC Programmable controller. 

CON Concentrator. OS Operator station. CM Control module. PLC Programmable controller. DM Data acquisition module. HC Hiway controller. 

The input/output units of the programmable controller constitute the interface between the PLC and the outside world. Hence, they are provided with the necessary signal conditioning functions which enable the PLC to be connected directly to the process actuators and transducers as desired. For this purpose the... 

Warnock<58) has compared the capabilities of the modern programmable controller with other controller hardware (Table 7.7). It is clear from this that the PLC has very attractive software and hardware features which make it a natural choice for a wide range of control strategies. 

This statement may be interpreted as— if XI or X2 is true and X3 is true, but X4 is not, then output R1 is energised . This is programmed into the PLC by pressing the appropriate keys on the keypad of the programming panel using the equivalent code (which in this case is for a Mitsubishi Melsec FI series programmable controller—but is fairly typical) ... 

Warnock, I. G. Programmable Controllers (Prentice-Hall, Hemel Hempstead, U.K., 1988). 

Mitsubishi Electric Corporation Instruction Manual H1-1B-041-G (1992). The Melsec-F programmable controller. 

Automation of Prep-HPLC. Reverse phase prep-HPLC separation has proven to be a very reproducible technique. For this reason, the process can be automated. In addition to the standard components of an HPLC system, the following are required for automation an autoinjector capable of large volume injections (2.0 to 5.0 ml), a programmable controller (a microprocessor controller), a fraction collector, and a waste valve (3-way valve) controlled by a solenoid (Fig. A). The microprocessor should allow programming of the solvent flow rate, the sequence for solvent gradient formation, the time of injection, advancement of the fraction collector (to collect specific fractions rather than just uniformly incremented advancement), and control of a waste valve. 

Figure 1. The Ferkin-Elmer laboratory for thermal analysis. From left to right the DSC-1B differential scanning calorimeter with evolved gas analyzer, the TGS-1 thermobalance (top to bottom), the recorder chart control, model UU-1 temperature programmer control, and model TMS-1 control unit. At right is the model TMS-1 thermomechanical analyzer.

Section 1 - Project and Process. This starts with the project definition (objective, description, location, product and raw material specifications, quantity, quality, output requirements, throughput for equipment sizing purposes). Closely linked with this is a statement of the mode of operation (e.g. day time only or 24 hour operation, continuous or batch processing) and expected control philosophy (centralised computer or local, methods of data collection and storage, programmable controllers or hard-wired ). 

---