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Transparent Mode
Transparent mode is suitable for host devices which provide their own data checking and control the flow of data. As data is received at the serial port, it is transmitted by radio and re-created at the serial port of all other modules with the same system address. There is no error checking carried out by the 405U modules and modules are not individually addressed - this is performed by the host devices.
Modules listen to the radio channel and hold off transmitting until the channel is clear, apart from this there is no other transmission delay. Transparent mode is suitable for PLC networks, or for a broadcast system where the same serial data is to be sent to multiple devices. In transparent mode, one repeater may be configured - the repeater will re-transmit any radio message it receives.
Controlled Mode
In controlled mode, each module is configured with a unit address, and the 405U modules perform error checking and acknowledgments. If a message is corrupted during the radio transmission, the source module will re-transmit the data up to four times until the data is received correctly. If reliable radio communications cannot be achieved, a communications failure output is provided as a discrete signal.
Controlled mode is suitable for host devices such as data loggers or intelligent transducers which do not carry out error checking or control the flow of data. In controlled mode, up to five intermediate repeaters may be configured in any one link. Destination addresses, and repeater messages may be preset using the configuration switches on the module, or they may be set from the host device using standard Hayes AT codes. This type of system would be suitable for a master device (such as a PC) polling several slave devices (for example, data loggers) to download information.
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