4 ms·
Big difference between RS422 and RS485 is the drivers for RS485 are required to survive a minus 7 volt difference between the two grounds. Old R422 drivers wou
by Gibbon1 2y ago
Big difference between RS422 and RS485 is the drivers for RS485 are required to survive a minus 7 volt difference between the two grounds.
Old R422 drivers would smoke if you got more than 7 tenths of a volt difference. Which would happen if you had a open ground. Or lighting hit. Or some big motor turned on. We had an RS422 based system with 50 units on one pair. One of them was holding the line. Coworker unplugged each one till he found it. And half of them didn't work after that.