Serial communications in its various forms – RS232, RS422 and RS485 – have been the communications methods of choice for most industrial machines since the beginning of industrial computerisation.
RS232 was suitable for short distance communications for terminals and printers but was unreliable over long distances and where interference from high-voltage machines occurred. RS485 replaced RS232 for long distance communications and was not affected by high voltage fluctuations in nearby cables and machines. RS485 also had the capability for multidropping of devices along the way.
Today there are many legacy machines which still have RS232 and RS485 communications requirements. However, many modern PCs do not have serial ports and Ethernet, USB and fibre-optic are becoming more popular for communications. The wiring of a factory, building or extended plant for communications can become a major headache for the IT department and plant engineers.
Fortunately there are solutions available in the form of serial and USB servers which can be connected to the company’s Ethernet network or even operate wirelessly. These servers with multiple serial or USB ports can be connected to the Ethernet network and addressed by any computer on the network. It is also possible to use Power over Ethernet (POE) to power these servers and reduce cable installation costs. Only the POE communication cables have to be pulled rather than power and communication cables.
The use of wireless communications to these servers makes it possible to deploy them quickly and easily wherever required, without the hassle of cabling to the point at which they are installed. The only requirement is power for the serial server.
An example of such a device is the ORing model IDS-5011-WG which is a single-port RS232/422/485 wireless server. ORing offers a range of Ethernet and wireless servers for serial and USB, which allow devices using these protocols to be deployed on any Ethernet network or remotely using wireless communications. With multiple port units it is possible to connect several units to a single serial server but access the individual units from multiple computers connected to the Ethernet network.
For more information contact Henry Hugo, Centurion Micro Electronics, +27 (0)21 851 4904, [email protected], www.cme.co.za
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| www: | www.cme.co.za |
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