1. BASIC ASSUMPTIONS
The basic idea of this work was to implement industrial machine remote control and  manipulation, via any type of computer networks. In the following chapter, the communication protocol's implementation between the microcontroller and the local computer as well as the communication between the local computer and the rest of the network is explained.

1.1. THE GLOBAL SCHEMATIC
In order to form a better picture about the entire project, the system's global scheme is presented in the following picture below. It is useful to pay attention to the connection between the microcontroller and the local computer (server) and on the other side the connection between the local computer (server) and the rest of the world (network). These connections will be discussed more thoroughly in the coming chapters.  (picture 1.1)

picture 1.1. System's global schematic

1.1.1. The Microcontroller
One of ANEL PLCs, based on Microchip's © PIC Controllers was used for implementation purposes. (picture 1.1) ANEL's PLCs use PIC 16F877's or 18F452's controllers. The PLC devices from theses series are typically built of three modules. (printed boards) The microcontroller is stationed on the elementary module, together with an LCD dot matrix display, a keyboard, additional supply circuits, buffers, signaling diodes, RS232 (RS485) interface, SPI, I²C output, etc. The digital input module is the second module. This module typically has 32 optocoupled inputs. The output module is the third module  and has 32 optocoupled outputs. Depending on the output types, ANEL has a couple of standard modules, triac, mosfet, relay, combined. These modules are designed to fit into microcontroller’s box. They fit one next to another, placed into corresponding slots, forming a clean package. As additional signalization, digital inputs and outputs have corresponding LED diodes. Except these standard modules, ANEL has specific modules for thermocouples, sensors, etc. They are usually placed in additional boxes and are not included in standard offers.

The software is also included. It allows programming, simulation, and device testing. These PLC devices are designed to control industrial machines. The software environment and hardware are designed to satisfy the most common needs in local industry. Software solutions are carefully designed and  represent genuine examples of ‘Real Time’ systems. The devices are auto-tested. Manual testing and setup is also possible. Error detection and data acquisition are implemented. Data can be sent to the local computer where further computation and analysis can be performed. The information about the machine’s up-time is also available. Parameters can be modified using the display's menu. Parameters that need to be remembered are stored in the internal EEPROM. The software is modularly designed. It means that more processes can live at the same time. For instance, the entire production process of the industrial machine is controlled while simultaneously communication is taking place, instant adjustments, error detection, etc. Software corrections and modifications can be directly performed  on PLC while the machine is working. This allows an easy and flexible development and simple and low cost  maintenance.

1.1.2. The Local Computer
The necessary communication software was installed on the local computer. The software servers to control the PLC and acquires the data from it. On the other side, network communication software was installed on the server to allow Internet access, LAN access and modem access.  (picture 1.1) The local computer is equipped with microphone, speakers and web cam, allowing the machine operator and programmer/engineer to communicate. (picture 1.1)

1.1.3 The Remote Computer
In order to be able to go online and establish the connection with the local computer, the remote computer needs to have a browser installed (Internet Explorer, Opera, Mozilla, Netscape) and a modem or an Ethernet card.  The industrial machine's work can be visually monitored from the remote computer. The machine can be remotely controlled from there, new software version releases can be uploaded from the remote computer. Industrial machine's parameters can be monitored from the remote computer. (temperature, humidity, pressure, speed, position, etc.) The remote computer is also equipped with microphone, speakers and web cam, allowing the programmer/engineer and machine operator to communicate. (picture 1.1)

1.1.4. The Industrial Machine or Simply Machine
All the controlled objects in industry will be called  Industrial Machines. These can be extruders, wood or metal processing machines, incubators, temperature regulators, elevators, lifts, etc. (picture 1.1)

1.1.5. Direction
The reference object is the local computer (server). Sending the data from the local PC (server) towards  PLC will be considered the default Data Sending direction. Analogously, when the local PC receives the data this direction will be called Data Receiving.  (picture 1.1)

1.1.6. Software Download
Downloading the new software version releases from the remote computer to the PLC will be called Software Download . (picture 1.1)

1.1.7. Manipulation
Operation execution requests, process parameter modification will be grouped under one word - Manipulation. 

1.1.8. Control and Acquisition
Transferring data about the running process from PLC to local computer and further to the remote computer will be called Acquisition. The ascuired data can further be recorded, computed and used in other applications.
(picture 1.1)

continuation...

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