GSM modem

GSM industrial Network Overview

Industrial networks can be implemented using GSM wireless technology. GSM is a well-known technology as you use it every day through you cell phones. But the use in the industrial networks is quite new. Industrial control is implemented through SMS and GSM modems. The idea of GSM industrial networks is o implement a single station without any wires for Ethernet or Telephone connections. Because the industrial networks are widely spread. Fieldbusses gather information from inputs and send to the desired outputs. Communication between stations (offices) and controllers (PLCs, RTUs) is done through Ethernet. A cheap and authentic source of information is Internet. This requires telephone connections.

GSM modems for Industrial Networks

You can easily get GSM modems from numerous vendors. GSM modems available now support 9600 Bits per second data transfer rate. This rate is considered quite high for industrial automation. Since industrial automation communicate through quite a small amount of data packets. The cost of GSM modems is relatively high but it reduces overall cost of the system.

Controlling the GSM modem

Like traditional modems GSM modems are also controlled through AT commands. So there is no requirement for newer mechanisms in GSM modem Communication. What GSM modem does is that it offers all its function as functional set for controllers. The most important of all is SMS.

Role of SMS in Industrial networks

Well SMS everybody knows is the short messaging service. But question is what it has to do in the industrial networks? And the answer is everything. The control system connected to a GSM modem can receive the text message from an event. The control systems implemented these days can easily translate and understand such simple text messages. For instance an error occurs and a sensor sends an “error” SMS to the control system.

Programming the Control System

All you need to do is to program the control system as well as the other attached services according to the GSM modems. When you are able to do so you can have a full duplex communication between controllers and sensors through SMS. The control system can also send SMS to a specific device such as a computer to send certain amount of data. You can use AT commands or additional micro controllers to achieve the programming syntax according to the desired application. With micro controllers the data can be saved and used even when GSM network is not available. Once you are done with the basic programming, you can connect to other GSM networks.

GSM limitations

The biggest problem with GSM is its service. There is no guarantee that the GSM signals will be available at all the time. Just like you have problem with SMS through mobile phones, you can have busy service error messages. Moreover some countries do not have GSM. The countries that do have GSM services cannot deploy the GSM services in all parts of the country.