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THE RS-423 STANDARDWhereas the RS-232 standard defines a bi-directional interface between exactly two communicators, the RS-423 standard defines a uni-directional interface between one transmitter and many receivers. For example, a single computer may need to update a number of terminals that are displaying, for example, a customers order information at multiple locations throughout a warehouse. The data direction is always in one direction. RS-423 allows for distances up to 4000 feet but limits data rates to only 100 kb/sec for a maximum of ten receivers. The voltage levels are +3.6 to +6 volts to represent a binary 0 and -3.6 to -6 volts to represent a binary 1. The voltage levels are defined relative to an earth ground potential assumed to be zero volts. Consequently a difference in ground voltage levels will result in the Common Mode Voltage problem that will confuse the data values. |
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