Remote monitoring and data acquisition of industrial process parameters through internet.

Rancea, Irina ; Sgarciu, Valentin ; Dichiu, Daniel 等

1. INTRODUCTION

Technological process supervision involves acquisition, processing and returning the commands for a large number of parameters. Using the Internet connection it is allowed to acquire data from long distances and to be concentrated in high performance servers.

The paper is focused on a solution for data acquisition/distribution using LabView framework, designed for long distance (Ahmad et. al, 2003). The advantages of control at distance of the industrial equipments are that people should not work in risk area, the possibility to control more than one equipment in the same time from different hosts, the possibility of making statistics in real time.

2. ACQUISITION SYSTEM

2.1 Hardware Resources for Data Acquisition

The system uses the multifunctional board of analogical and numerical inputs-outputs NI PCI-6014E from National Instruments (National Instruments Data Sheet).

I/O Connector--the connector is prolonged through a ribbon cable next to a connection board where, through screw terminals, electrical links with real world are made

* Analog Input--contains the analogical multiplexer MUX, the instrumental amplifier NI-PGIA with programmable amplification factor, the numerical-analogical converter ADC, the temporary memory for numerical equivalents of input signals AI FIFO and the trigger modes for input signals Analog Trigger

* Analog Output--contains two numerical-analogical converters (DAC0 and DAC1) and a memory (AO FIFO) where the numerical equivalents of analogical output signals are brought

* Digital I/O--numerical inputs/outputs block--8 pins for general usage that can be individually software configured

* Two counters (24 bits), each one having two inputs (Source and Gate), one output (Out) and two software registers

* PFI--programmable Function Interface--10 connections with the outside of the board through which one can collect temporary signals from outside and can generate different kinds of internal board's signals

* Digital Routing--responsible with the management of data flow between PC's pipe-line and the acquisition systems. The numeric routing circuits use FIFO memory in each subsystem to ensure efficient flow of data.

* RTSI--Real Time System Integration Bus--an additional pipeline through which one can achieve synchronization for specific measuring functions,

* Bus Interface--contains the hardware components through which the acquisition board connects to the PC's pipe-line

[FIGURE 1 OMITTED]

2.2 Application Architecture

The monitoring and command configuration is installed on a local workspace; the access to the application server is done through an Internet connection (Shirer, 2001; Matousek, 2006) (Fig. 1.) For compatibility both application server and the workspaces have installed the LabView 6.1. framework. (National Instruments) The acquisition board NI-PCi-6014E allows the measuring of continuous tension voltages and TTL numeric signals, while the commands could be analogical or TTL numeric.

3. CASE STUDY

3.1 Monitoring the temperature of the heating oven

The temperature acquisition and bi-positional command of the heating oven layout schema is presented in Fig. 2.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

A part of the application goal is to acquire the analogical signal provided by the RTD and also generating a stop command when the superior temperature is reached. When the oven temperature reaches its inferior limit, the heating process is restarted. (The goal is to obtain a positional temperature regulation). So, the two sensors have the role to maintain the oven temperature between certain limits. Because of the constructive differences between them, one will effectively command the oven starting/stopping, while the second will have a protection role in the installation--it will stay between the limits and in case of the first sensor's malfunction, it will take over the tasks of the first one. The logic of the application is based on RS two-state. In the right hand side of the panel from Fig. 3 there are provided the commands for setting the optimum working values for each thermo element. As long as the current value is out of the fixed values the bare graph indicator will be doubled by a different coloured line. The wave graph allows a permanent monitoring of the current values.

We tested the behaviour when having passive filtration (Fig. 6), numerical filtration and the case of no filtration (Fig. 3).

The application is made up of several modules:

* Data acquisition module--deals with starting, configuration and initialization of reading and also with shutdown of the connection with the data acquisition board. At this moment it should be set which channels are used for data acquisition. The number of samples and the rate of sampling. After these, the data acquired are processed by the LabView.

* Conversion module--converts the voltage into temperature so that the user can monitor and take decision based on "human readable data"

* Communication module--responsible with the remote data transmission. It was developed using NI DataSocket Server-Client communication. The server module writes data in the server, and every client can read/write data due to his rights. Also, the server application can read command data from the server and apply it to the sensors (Fig.4 and Fig. 5).

* Command module--transmits on/off signals based on the information received from the logical module

* Logical module--it has to keep the temperature between the boundaries set by the user. One characteristic of the equipment should be taken into consideration--the thermal inertia due to the resistance of the system.

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

* One can notice that when the command sensor has reached the inferior boundary due to the sensor's protection elements' resistance, certain inertia takes place and the temperature of the precincts drops by at most 1 Celsius degree below the inferior boundary. This problem will be solved in the future by using better sensitive elements.

4. CONCLUSIONS

The application was designed and developed to test the possibility of adding remote controlling/monitoring. It was used for a series of experiments between several laboratories.

As main part of this paper we presented the process of remote controlling of the precinct temperature, but the server can deal with more than one application in the same time--it can monitor parameters provided by 16 sensors and it can lead till four industrial equipments in the same time, using the data acquisition board NI PCI-6014E.

5. REFERENCES

Ahmad, M.R.; Khan, N.; Hooong, C.C.; Abas, N. (2003). Remote data acquisition through Internet based telemetry, Research and Development. 2003. Scored 2003. Proceedings. Student Conference, pp. 237-244, ISBN 0-7803-8173-4, August 2003

Matousek, M. (2006). Internet Data Acquisition, Space Mission Challenges for Information Technology 2006.SMC-IT 2006, Second IEEE International Conference, ISBN 0-7695-2644-6, July 2006

National Instruments Resources, LabView Graphical Programming, Available from: http://www.rmuti.ac.th/ ~nopparat/document/pdf/Labview%20Graphical%20Progra mming.pdf Accessed: 2008-05-25

National Instruments, NI PCI-6014E Data Sheet, Available from: http://sine.ni.com/nips/cds/view/p/lang/en/nid/11442 Accessed: 2008-05-25

Shirer, D. (2001). Labview 6i Adds Internet Features to Data Acquisition Environment. Computing in Science and Engineering, Vol. 3, No. 4, (July/August 2001), pp. 8-11, ISSN 152109615

Vlad, M.; Sgarciu, V.; Rancea, I. (2005). Acquisition and monitoring of process parameters using Internet, CSCS15--15th International Conference on Control Systems and Computer Science, Politehnica University Bucharest, Vol. 1, pp. 8-14