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): 23/44頁(yè)
文件大?。?/td> 628K
代理商: RS-422
20
RS-422/485 Application Note
B&B Electronics -- PO Box 1040 -- Ottawa, IL 61350
PH (815) 433-5100 -- FAX (815) 434-7094
Chapter 3: Selecting RS-422 and RS-485 Cabling
Cable selection for RS-422 and RS-485 systems is often neglected.
Attention to a few details in the selection process can prevent the costly
prospect of re-pulling thousands of feet of cable.
Number of Conductors
The signal ground conductor is often overlooked when ordering cable. An
extra twisted pair must be specified to have enough conductors to run a signal
ground. A two wire system then requires two twisted pair, and a four wire
system requires three twisted pair.
Shielding
It is often hard to quantify if shielded cable is required in an application or
not. Since the added cost of shielded cable is usually minimal it is worth
installing the first time.
Cable Characteristics
When choosing a transmission line for RS-422 or RS-485, it is necessary
to examine the required distance of the cable and the data rate of the system.
The Appendix to EIA RS-422-A Standard presents an empirical curve that
relates Cable Length to Data Rate for 24 AWG twisted-pair telephone cable
that has a shunt capacitance of 16 pF/ft. and is terminated in 100 ohms (see
Figure 3.1). This curve is based on signal quality requirements of:
a). Signal rise and fall time equal to, or less than, one-half unit interval at
the applicable modulation rate.
b). The maximum voltage loss between driver and load of 6 dB.
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
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