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Alpha » CDataType » QbasicFAQ_Function » BeginnersGuideToVB » JAP » CFclose » WhatLinksHere » QbasicFAQ_Input » LinkedList » Edit » rs 485
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[purple][b][size=3]RS-485 [/size][/b][/purple][br][br]
The RS-485 standard was developed jointly by two trade associations: the Electronic
Industries Association ( ?EIA) and the Telecommunications Industry Association (TIA).
The EIA once labeled all its standards with the prefix "RS" (Recommended Standard).
Today, various extensions of the RS-485 standard accommodate a large variety of applications.
The RS-485 and RS-422 standards have much in common, and are often confused for
that reason.The table below compares the two. RS-485, which specifies bidirectional,
half-duplex data transmission, is the only EIA/TIA standard that allows multiple receivers
and drivers in "bus" configurations. EIA/TIA-422, on the other hand, specifies a single,
unidirectional driver with multiple receivers. RS-485 parts are backward-compatible and
interchangeable with their RS-422 counterparts, but RS-422 drivers should not be used
in an RS-485 system because they cannot relinquish control of the bus.
[b]RS-485 and RS-422 Standards[/b]
[pre]
RS-422 RS-485
Mode of operation Differential Differential
Allowed no. of Tx and Rx 1 Tx, 10 Rx 32 Tx 32 Rx
Maximum cable length 4000ft length 4000ft length
Maximum data rate 10Mbps 10Mbps
Minimum driver output range ±2V ±1.5V
Maximum driver output range ±5V ±5V
Maximum driver
short-circuit current 150mA 250mA
Tx load impedance 54 100
input sensitivity ±200mV ±200mV
Maximum Rx input resistance 4k 12k
Rx input voltage range ±7V -7V to +12V
Rx logic high >200mV >200mV
Rx logic low <200mV <200mV
[/pre]¶
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Alpha » CDataType » QbasicFAQ_Function » BeginnersGuideToVB » JAP » CFclose » WhatLinksHere » QbasicFAQ_Input » LinkedList » Edit » rs 485
Displaying differences between revision 2 and the latest revision
[purple][b][size=3]RS-485 [/size][/b][/purple][br][br]
The RS-485 standard was developed jointly by two trade associations: the Electronic
Industries Association ( ?EIA) and the Telecommunications Industry Association (TIA).
The EIA once labeled all its standards with the prefix "RS" (Recommended Standard).
Today, various extensions of the RS-485 standard accommodate a large variety of applications.
The RS-485 and RS-422 standards have much in common, and are often confused for
that reason.The table below compares the two. RS-485, which specifies bidirectional,
half-duplex data transmission, is the only EIA/TIA standard that allows multiple receivers
and drivers in "bus" configurations. EIA/TIA-422, on the other hand, specifies a single,
unidirectional driver with multiple receivers. RS-485 parts are backward-compatible and
interchangeable with their RS-422 counterparts, but RS-422 drivers should not be used
in an RS-485 system because they cannot relinquish control of the bus.
[b]RS-485 and RS-422 Standards[/b]
[pre]
RS-422
Mode of operation Differential Differential
Allowed no. of Tx and Rx 1 Tx, 10 Rx 32 Tx 32 Rx
Maximum cable length 4000ft length 4000ft length
Maximum data rate 10Mbps 10Mbps
Minimum driver output range ±2V ±1.5V
Maximum driver output range ±5V ±5V
Maximum driver
short-circuit current 150mA 250mA
Tx load impedance 54 100
input sensitivity ±200mV ±200mV
Maximum Rx input resistance 4k 12k
Rx input voltage range ±7V -7V to +12V
Rx logic high >200mV >200mV
Rx logic low <200mV <200mV
[/pre]¶
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