SN65HVD96

SLLSE35 – JUNE 2010

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APPLICATION INFORMATION

Sympol™ States

Using Sympol to Achieve Immunity to Crossed Bus Wire

Many applications which use RS-422 or RS-485 are wired on-site by third-party installers. This opens the door to

the possibility of miss-wiring, especially for far-flung networks with many stations (or nodes). Neither RS-422 nor

RS-485 allows correct communications when the bus wires (typically a twisted-pair) are swapped.

The existing solutions for this case require active intervention, either by the installer or maintenance technician,

or by an automated controller. Sympol offers a way to replace RS-422 or RS-485 networks with communication

over the same bus lines. Due to the innovative nature of Sympol signalling levels, a Sympol network is immune

to communication errors caused by crossed bus wires.

Signaling levels are similar to RS-422 and RS-485, so signalling rates, cable lengths, and noise immunity will be

comparable.

Sympol is NOT interoperable with RS-422 or RS-485; that is, designers may not mix Sympol nodes with existing

RS-485 nodes.

PARAMETER MEASUREMENT INFORMATION

Input generator rate is 100kbps, 50% duty-cycle, transition times less than 6 ns for all figures.

Figure 2. Measurement of Driver Differential Output Voltage With Common-Mode Load

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