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1.5 CABLE FOR RS232, RS422, RS485 SERIAL DATA LINKS
Where cables are listed as being for RS422 or RS485 serial data links, cable classed as "Low
Capacitance Data Cable for RS422/RS485 Serial Links" is required, in accordance with the
following requirements:
Where cables are listed as being for RS232, cable meeting the requirements for RS422 and RS485
will be more than adequate. Since RS232 is generally unsuitable for other than short local links, it
is unlikely that special purchase of cable meeting only the requirements of RS232 data links would
be worthwhile.
Low capacitance Data Cable suitable for RS422/RS485 Serial Links- Cable Specification:
Construction : Conductors formed into twisted pairs, with single overall foil
screen and overall tinned copper braid screen, with overall
insulating sheath.
Conductors: Tinned Copper, stranded. For mechanical reliability,
22AWG/
size.
Number of twisted pairs required: As shown on Converteam interconnection diagrams.
(3 pairs normally required. 2 pairs for 2-wire RS 485, or
where data flow is in one direction only. One of these pairs
is required for the 0V connection.)
Circuit voltage: 24V
Characteristic Impedance: 100 W to 120 W.
Capacitance (maximum): 45pF/m between conductors of one pair.
75pF/m between one conductor and all others and screen
connected together.
Resistance (maximum) 80 W/km
Velocity of Propagation (minimum) 70%
Notes:
1) If any cable run will exceed
be necessary.
2) Each cable should only carry one Serial Data Link.
3) When data flow is known to be in one direction only, requiring only one pair for data (e.g.
as in the case of printer connections), a 2-pair cable may be used, with the second pair used
as the 0V connection.
4) The number of pairs required will be indicated on Converteam Schedules/Interconnection
Diagrams.
The following cable types are known to have suitable electrical properties, but the Cable Contractor
must check that the cable construction and materials are acceptable for the application:
a) For four-wire links, using the third twisted pair as the ground connection between serial
ports: Belden type
Belden type 8103 (24 AWG),has suitable electrical properties but the conductor size is
smaller than recommended by Converteam, and may not be accepted by the Classification
Society.
b) For two-wire links, using the second twisted pair as the ground connection between serial
ports: Belden type
properties but the conductor size is smaller than recommended by Converteam, and may not
be accepted by the Classification Society.
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求助大家?guī)兔x一下,有沒有這方面的資料!
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我們是國內(nèi)最早生產(chǎn)RS485電纜的廠家之一。
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通用型現(xiàn)場總線系列電纜
特性阻抗為120Ω的雙絞屏蔽電纜廣泛用于RS485/422、CANBUS等總線，該系列電纜規(guī)格很多，請?zhí)峁╇娎|的敷設(shè)環(huán)境、通信速率、最大無中繼傳輸距離等參數(shù)，我們將依照具體情況推薦最適當(dāng)?shù)漠a(chǎn)品。一般推薦如下：
普通雙絞屏蔽型電纜 STP-120Ω（for RS485 & CAN） one pair 20 AWG ，電纜外徑
普通雙絞屏蔽型電纜 STP-120Ω（for RS485 & CAN） one pair 18 AWG ，電纜外徑
鎧裝雙絞屏蔽型電纜 ASTP-120Ω（for RS485 & CAN） one pair 18 AWG ，電纜外徑
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好資料
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