參數(shù)資料
型號(hào)： RS-422
廠商： Electronic Theatre Controls, Inc.
英文描述： RS-422 AND RS-485 APPLICATION NOTE
中文描述： RS - 422和RS - 485接口應(yīng)用筆記
文件頁(yè)數(shù)： 22/44頁(yè)
文件大?。?/td> 628K
代理商： RS-422
RS-422/485 Application Note
19
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 434-7094
Example 2. 32 node, RS-485 network without termination
Each RS-485 node has a load impedance of 12K
. 32 nodes in parallel
gives a total load of 375
. In order to maintain at least 200 mV across
375
we need a current of 0.53 mA. To generate this current from a 5V
supply requires a total resistance of 9375
maximum. Since 375
of this
total is in the receiver load, our bias resistors must add to 9K
or less.
Notice that very little bias current is required in systems without termination.
Bias resistors can be placed anywhere in the network or can be split
among multiple nodes. The parallel combination of all bias resistors in a
system must be equal to or less than the calculated biasing requirements.
B&B Electronics uses 4.7K
bias resistors in all RS-485 products. This
value is adequate for most systems without termination. The system designer
should always calculate the biasing requirements of the network. Symptoms
of under biasing range from decreased noise immunity to complete data
failure. Over biasing has less effect on a system, the primary result is
increased load on the drivers. Systems using port powered RS-232 to RS-485
converters can be sensitive to over biasing.
Extending the Specification
Some systems require longer distances or higher numbers of nodes than
supported by RS-422 or RS-485. Repeaters are commonly used to overcome
these barriers. An RS-485 repeater such as B&B Electronics’ 485OP can be
placed in a system to divide the load into multiple segments. Each “refreshed”
signal is capable of driving another 4000 feet of cable and an additional 31 RS-
485 loads.
Another method of increasing the number of RS-485 nodes is to use
low load type RS-485 receivers. These receivers use a higher input impedance
to reduce the load on the RS-485 drivers to increase the total number of nodes.
There are currently half and quarter load integrated circuit receivers available,
extending the total allowable number of nodes to 64 and 128.
相關(guān)PDF資料
PDF描述
RS-485 RS-422 AND RS-485 APPLICATION NOTE
RS-MK-X2010 High Integrity FM Transceiver
RS3FS SDR Cable Assembly; Connector Type A:micro D Ribbon Plug; Connector Type B:micro D Ribbon Plug; Cable Length:2m; No. of Contacts:26; Pitch Spacing:0.8mm RoHS Compliant: Yes
RS3FS Damper Diodes (For TV)
RS4FS SDR Cable Assembly; Connector Type A:micro D Ribbon Plug; Connector Type B:micro D Ribbon Plug; Cable Length:5m; No. of Contacts:26; Pitch Spacing:0.8mm RoHS Compliant: Yes
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
RS422-GE1 制造商:Carlo Gavazzi 功能描述:CABLE FOR GE90
RS422-MI1 制造商:Carlo Gavazzi 功能描述:CABLE FOR MITS MASTER
RS422-MI2 制造商:Carlo Gavazzi 功能描述:CABLE FOR MITS MASTER
RS422-MI3 制造商:Carlo Gavazzi 功能描述:CABLE FOR MITS MASTER
RS422-OM2 制造商:Carlo Gavazzi 功能描述:CABLE FOR OMRON MASTER
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*