DSAI130中文PDF使用手冊,ABB卡件
EIA-530連接EIA-530接口在功能上補(bǔ)充了EIA-232-D接口。EIA-530標(biāo)準(zhǔn)定義了該接口的機(jī)械方面，用于傳輸串行二進(jìn)制數(shù)據(jù)，包括同步和異步。它適用于平衡（雙端）和不平衡（單端）信號，并提供更高的使用相同的DB-25連接器時(shí)，數(shù)據(jù)速率高于EIA-232-D。MVME2700符合EIA-232-D規(guī)范。請注意盡管EIA-232-D標(biāo)準(zhǔn)建議使用短互連電纜長度不超過50英尺（15m），較長電纜如果在接口點(diǎn)（包括信號終端）不超過2500pF。接口特性在指定DTE之間串行二進(jìn)制數(shù)據(jù)交換的參數(shù)時(shí)和DCE設(shè)備，EIA-530標(biāo)準(zhǔn)假設(shè)使用平衡線路，除遠(yuǎn)程環(huán)回、本地環(huán)回和測試模式線路外，它們是單端的。
DSAI130中文PDF使用手冊平衡線路數(shù)據(jù)交換通常是優(yōu)先用于不平衡線路數(shù)據(jù)交換，其中任何以下條件為準(zhǔn)：? 互連電纜太長，無法有效平衡活動
? 互連電纜暴露于外部噪聲源這可能會導(dǎo)致多余電壓超過測量的±1V在電纜負(fù)載端，50? 電阻器代替發(fā)射器。
? 有必要盡量減少對其他信號的干擾。
? 可能需要反轉(zhuǎn)信號（例如，加極性正負(fù)極性標(biāo)記可以通過反轉(zhuǎn)電纜對）。
EIA-530接口發(fā)射器和接收器參數(shù)適用于MVME2700列在下表中。正確接地需要考慮的一個(gè)重要問題是接地引腳的使用。有兩個(gè)標(biāo)有GND的引腳。針腳7是信號接地，必須連接到完成電路的遠(yuǎn)程設(shè)備。針腳1是機(jī)箱接地，但它必須小心使用。機(jī)箱連接至電源接地通過電源線中的綠色導(dǎo)線，并且必須連接到符合電氣規(guī)范。
問題是，當(dāng)裝置連接到不同的電源插座時(shí)，地電位可能有幾伏的差異。每個(gè)的If引腳1該設(shè)備通過電纜和其他設(shè)備互連，可能會產(chǎn)生幾安培的電流。這種情況不僅對典型電纜中的小導(dǎo)線，但也可能產(chǎn)生電噪聲導(dǎo)致數(shù)據(jù)傳輸錯誤。
EIA-530 Connections
The EIA-530 interface complements the EIA-232-D interface in function.
The EIA-530 standard defines the mechanical aspects of this interface,
which is used for transmission of serial binary data, both synchronous and
asynchronous. It is adaptable to balanced (double-ended) as well as
unbalanced (single-ended) signaling and offers the possibility of higher
data rates than EIA-232-D with the same DB-25 connector.The MVME2700 conforms to EIA-232-D specifications. Note that
although the EIA-232-D standard recommends the use of short
interconnection cables not more than 50 feet (15m) in length, longer cables
are permissible provided the total load capacitance measured at the
interface point and including signal terminator does not exceed 2500pF.Interface Characteristics
In specifying parameters for serial binary data interchange between DTE
and DCE devices, the EIA-530 standard assumes the use of balanced lines,
except for the Remote Loopback, Local Loopback, and Test Mode lines,
which are single-ended. Balanced-line data interchange is generally
employed in preference to unbalanced-line data interchange where any of
the following conditions prevail:
? The interconnection cable is too long for effective unbalanced
operation.
? The interconnection cable is exposed to extraneous noise sources
that may cause an unwanted voltage in excess of ±1V measured
differentially between the signal conductor and circuit ground at the
load end of the cable, with a 50? resistor substituted for the
transmitter.
? It is necessary to minimize interference with other signals.
? Inversion of signals may be required (for example, plus polarity
MARK to minus polarity MARK may be achieved by inverting the
cable pair).
EIA-530 interface transmitter and receiver parameters applicable to the
MVME2700 are listed in the following tables.Proper Grounding
An important subject to consider is the use of ground pins. There are two
pins labeled GND. Pin 7 is the signal ground and must be connected to the
distant device to complete the circuit. Pin 1 is the chassis ground, but it
must be used with care. The chassis is connected to the power ground
through the green wire in the power cord and must be connected to be in
compliance with the electrical code.
The problem is that when units are connected to different electrical outlets,
there may be several volts of difference in ground potential. If pin 1 of each
device is interconnected with the others via cable, several amperes of current could result. This condition may not only be dangerous for the
small wires in a typical cable, but may also produce electrical noise that
causes errors in data transmission.
