White paper warns: Data risk for RS-485 users
Liberty, SC – “Many RS-485 users are completely unaware that they are taking unnecessary risk with their data because of the method they use for driver control,” said Jeff Hunter, design engineer at
. New driver control methods can help RS-485 eliminate the risks of data contention and corruption, Hunter says.
The EIA RS-485 specification does not stipulate the method for controlling the driver; therefore, several options have evolved. Some have significant risk of data contention and corruption because of the time required for a device to relinquish control of the network once communication is complete.
Common RS-485 driver control methods are:
– Application program control (under Microsoft Windows);
– One-shot (which uses a circuit to activate the enable/deactivate signal);
– Enable driven when data present (a hardware approach connecting the transmitter data line to the transmitter enable pin);
– Automatic driver control (in which software automatically recognizes commands to transmit/disable); and
– Automatic hardware enable (the latest innovation that uses hardware circuitry on the board to control RS-485 communications).
A Sealevel Systems white paper, “
Eliminate the Risk of RS-485 Data Corruption
,” evaluates the methods.
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