White paper warns: Data risk for RS-485 users

Many RS-485 users are unaware that they are taking unnecessary data risks because of the method they use for driver control, says a design engineer at Sealevel Systems. Common driver control methods are....
By Control Engineering Staff April 8, 2008

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

Sealevel Systems

. 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.
See related story:

Sealevel Systems release Windows XP serial driver

.

Control Engineering News Desk
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