JPS62136145A - I:n data transmission system - Google Patents

I:n data transmission system

Info

Publication number
JPS62136145A
JPS62136145A JP27646085A JP27646085A JPS62136145A JP S62136145 A JPS62136145 A JP S62136145A JP 27646085 A JP27646085 A JP 27646085A JP 27646085 A JP27646085 A JP 27646085A JP S62136145 A JPS62136145 A JP S62136145A
Authority
JP
Japan
Prior art keywords
current
transmission
switching element
transmission line
station
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP27646085A
Other languages
Japanese (ja)
Inventor
Masao Tsukada
塚田　正男
Kazuhiro Ohashi
一弘 大橋
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fuji Electric Co Ltd
Fuji Facom Corp
Original Assignee
Fuji Electric Co Ltd
Fuji Facom Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Fuji Electric Co Ltd, Fuji Facom Corp filed Critical Fuji Electric Co Ltd
Priority to JP27646085A priority Critical patent/JPS62136145A/en
Publication of JPS62136145A publication Critical patent/JPS62136145A/en
Pending legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
    • H03K19/0175—Coupling arrangements; Interface arrangements
    • H03K19/017545—Coupling arrangements; Impedance matching circuits

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Physics & Mathematics (AREA)
  • Computing Systems (AREA)
  • General Engineering & Computer Science (AREA)
  • Mathematical Physics (AREA)
  • Small-Scale Networks (AREA)

Abstract

PURPOSE:To minimize the variation of an impedance of a transmission line viewed from the sending end regardless of the change in number of sets of installed stations by adopting the data transmission form a conventional voltage injection system into a current injection system. CONSTITUTION:Current transformers or the like are used as current injection means 15, 151-15N and components such as serch coils or Hall effect elements sending a current in contactless with a transmission lie are employed for current detection elements 17, 171-17N. A master station 11 operates to open a switching element 18 just before a command is sent so a to connect an injection terminal of the current injection means 15 to a transmission line 13. The current signal flowing through the line 13 is sensed noncontactly by the current detection elements 171-17N of slave stations 121-12N and decoded by reception circuits 161-16N. The master station 11 closes the switching element 18 just after the transmission is finished and enters the reception enable state. On the other hand, a slave station receiving a call opens the switching element 181 to connect the injection terminal of the current injection means 151 to the transmission line 13.

Description

【発明の詳細な説明】[Detailed description of the invention] 【発明の属する技術分野】[Technical field to which the invention pertains]

本発明は１個の親局と複数の子局とを環状の伝送路を介
して接続し、親局と子局との間でデータの送受信を半二
重通信方式で行うようにした１：Ｎデータ伝送方式に関
するものであり、特に親局からの指令（下り）信号によ
り特定の子局が選択され、子局では制御対象物を操作し
、その結果を親局に応答（上り）信号として返送する方
式である。The present invention connects one master station and a plurality of slave stations via a circular transmission path, and transmits and receives data between the master station and the slave stations using a half-duplex communication method. This is related to the N data transmission method, in particular, a specific slave station is selected by a command (downlink) signal from the master station, the slave station operates the object to be controlled, and the result is sent as a response (upstream) signal to the master station. This method involves sending it back.

【従来技術とその問題点】[Prior art and its problems]

１個の親局と複数の子局とを共通の伝送路を介して接続
し、親局と子局との間でデータの送受信を半二重通信方
式で行うようにした従来の１：Ｎデータ伝送方式システ
ムでは、各局の送信回路は電圧注入方式（データを電圧
信号として伝送路に送出する）であり、これに対応して
受信回路も当然のことながら電圧検出方式で行われてい
る。そのために各局と伝送路との接続には絶縁を目的と
して変圧器が使用されている。このように変圧器が使用
された従来のにＮ伝送システムの等価回路を第４図に示
す。図において１は親局、２Ｉ〜２Ｎは子局、３は伝送
路、４は送信回路、５は受倍回路、６は送信出力インピ
ーダンス、７は等個入力インピーダンスを示している。 ここで、送信出力インピーダンス６と等個入力インピー
ダンス７は変圧器の励磁インピーダンスと送信回路４、
受信回路５のインピーダンスによるものであり、このよ
うなインピーダンスが存在する結果、（１）電圧検出方
式となるため、伝送路と各局の結合は密となり、送信端
からみた伝送路のインピーダンスは設置局の台数及びそ
の位置により変動する。 （２）データ伝送とは直接関係のない絶縁変圧器の励磁
損失が発生し、送信電力が無駄になる。 等の欠点がある。The conventional 1:N method connects one master station and multiple slave stations via a common transmission path, and sends and receives data between the master station and slave stations using a half-duplex communication method. In the data transmission system, the transmitting circuit of each station uses the voltage injection method (data is sent out as a voltage signal to the transmission path), and correspondingly, the receiving circuit also uses the voltage detection method. For this reason, transformers are used to connect each station to the transmission line for the purpose of insulation. FIG. 4 shows an equivalent circuit of a conventional N transmission system in which a transformer is used in this manner. In the figure, 1 is a master station, 2I to 2N are slave stations, 3 is a transmission path, 4 is a transmitting circuit, 5 is a receiver circuit, 6 is a transmission output impedance, and 7 is an equal number of input impedances. Here, the transmission output impedance 6 and the equal input impedance 7 are the excitation impedance of the transformer and the transmission circuit 4,
This is due to the impedance of the receiving circuit 5, and as a result of the existence of such impedance, (1) voltage detection method is used, so the coupling between the transmission line and each station is tight, and the impedance of the transmission line seen from the transmitting end is the same as that of the installed station. It varies depending on the number of units and their location. (2) Excitation loss of the isolation transformer, which is not directly related to data transmission, occurs, and transmission power is wasted. There are drawbacks such as.

【発明の目的】[Purpose of the invention]

本発明は、データ伝送を従来の電圧注入方式から電流注
入方式とすることにより、設置燭台数の変化にかかわら
ず送信端からみた伝送路のインピーダンスの変動が僅少
となり、かつ送信電力の無駄も少なくした１：Ｎ伝送方
式を提供することを目的とする。By changing data transmission from the conventional voltage injection method to a current injection method, the present invention minimizes fluctuations in the impedance of the transmission path as seen from the transmitting end regardless of changes in the number of installed lamps, and reduces waste of transmission power. The purpose is to provide a 1:N transmission system with

【発明の要点】[Key points of the invention]

本発明の要点は、１個の親局と複数の子局とを環状の伝
送路を介して接続し、親局と子局との間でデータの送受
信を行うようにしたｌ：Ｎデータ伝送方式において、親
局および各子局には、送信回路と、前記伝送路に直列挿
入された開閉素子と、該開閉素子に並列接続され、前記
送信回路からの送信データに応じて前記伝送路に電流信
号を送出する電流注入手段と、前記伝送路に流れる電流
信号を非接触で検出する電流検出手段と、該電流検出手
段により検出された電流信号を受信する受信回路とを設
け、前記親局および各子局は送信時のみ自局内の前記開
閉素子を開いて前記電流注入手段により前記伝送路に電
流信号を送出するように構成した点にある。The gist of the present invention is l:N data transmission in which one master station and a plurality of slave stations are connected via a circular transmission path, and data is sent and received between the master station and the slave stations. In this method, the master station and each slave station include a transmission circuit, a switching element inserted in series in the transmission line, and a switching element connected in parallel to the switching element, and a transmission circuit connected to the transmission line in response to transmission data from the transmission circuit. A current injection means for sending out a current signal, a current detection means for contactlessly detecting the current signal flowing through the transmission line, and a receiving circuit for receiving the current signal detected by the current detection means are provided, and the master station Further, each slave station is configured to open the switching element within itself only when transmitting, and send out a current signal to the transmission path by the current injection means.

【発明の実施例】[Embodiments of the invention]

第１図は本発明による１：Ｎデータ伝送方式を実現する
ためのシステム構成図を示している。図において、１１
は親局、１２．〜１２Ｎは子局、１３は伝送路、１４．
１４．〜１４Ｎは送信回路、１５．１５．〜１５Ｎは電
流注入手段、１６，１６１〜１６．は受信回路、１７．
１７゜〜１７，４は電流検出素子、１８．１８１〜１８
、は開閉素子、１９、〜１９．は制御対象物を示してい
る。 このような構成において各子局１２．〜１２．には固有
のアドレスが割付けられており、親局からアドレス指定
された子局のみが応答するように構成されている。また
電流注入手段１５．１５１〜１５Ｎとしては変流器等が
使用され、電流検出素子１７．１７．〜１７、としては
サーチコイル、ホール効果素子等のように伝送路に非接
触で電流を検出可能なものが使用される。 第１図に示すシステムでは開閉素子１８．１８１〜１８
、は常閉接点であり、これにより各電流注入手段が短絡
されることにより伝送路１３は環状に形成される。次に
このシステムのデータ伝送の例として、親局１１から指
令を発し、呼出しを受けた子局（指令中に含まれるアド
レス情報による。）が応答を返送する場合の動作につい
て説明する。まず、親局１１は指令を発する直前に開閉
素子１８を開状態になるように操作し、電流注入手段１
５の注入端を伝送路１３に接続する。このとき、各子局
１２．〜１２゜の開閉素子１８＋〜１８ｓは閉状態とな
っている。したがって、親局１１の送信回路１４がらの
データ（子局のアドレス情報と操作指令）に応じて電流
注入手段１５より伝送路１３に注入される電流信号は伝
送路１３を流れる。伝送路１３を流れる電流信号は各子
局１２１〜１２８の電流検出素子１７．〜１７Ｈにより
非接触で検出され、受信回路１６＋〜１６Ｎにより解読
される。この検出された電流信号により呼出しを受けた
（選択された）子局はこの電流信号による指令に応じて
制御対象物（１９１〜１９Ｎ）を操作する。 親局１１は送信終了後直ちに開閉素子１８を閉状態とし
、受信可能状態となる。一方、呼出しを受けて制御対象
物の操作を終了した子局（例えば子局１２＋　とする）
は、親局と同じ手順で、まず開閉素子１８．を開状態と
して電流注入手段１５．の注入端を伝送路１３に接続す
る。このとき、親局１１の開閉素子１８と子局１２！〜
１２．の開閉素子１８□〜１８．は閉状態となっている
。次に送信回路１４ｔからのデータ（応答信号）に応じ
て電流注入手段１５．より伝送路１３に電流信号を注入
する。注入された電流信号は親局１１と子局１２２〜１
２Ｎの電流検出素子１７゜１７□〜１７Ｎにより検出さ
れ受信回路１６．１６□〜１６Ｎにより解読される。子
局１２＋　は応答信号の送信が終了すると直ちに開閉素
子１８１を閉状態として受信状態となる。 以上の動作の繰り返しにより、親局１１は順次子局１２
＋　””１２Ｎを選択し、１台の親局１１とＮ台の子局
１２．〜１２．の間でデータの伝送が行われ、１対Ｎ方
式の遠方監視制御が行われる。 電流検出手段としては例えばサーチコイルがあげられる
が、以下にサーチコイルによる検出原理について説明す
る。 第２図は伝送線とサーチコイルの相対位置関係を示して
いる。図において、２０は伝送線、２１はサーチコイル
、２２は強磁性体である。第２図において、紙の表から
裏へ、周波数ｒ（Ｈｘ）、電流Ｉ（Ａ）が流れているも
のとすると、サーチコイル２１までの距離ｒ　（ｍ）に
おける磁界Ｈはアンペア周回路の法則より、 Ｈ＝　−（ＡＴ／ｍ）　　−−−−−−−−−−・・−
・−・−・・−（１）２　π　ｒ となる。従って、磁束密度Ｂ−μＨ（ｗ　ｂ　／ｍ２〕
より、サーチコイル２１の半径ａ　　（ｍ）とすれば、
磁束の総数Φは、 Φ＝π・ａ２　・Ｂ＝π・ａ２　・μＨ■ となる。そこでサーチコイル２１に誘起される電圧Ｅは
、サーチコイル２１の巻数をＮとすると、となる。サー
チコイル２１が強磁性体２２に巻かれている場合には強
磁性体２２に磁束が吸い寄せられるような現象が生ずる
ので、空心コイルの場合に比べて（３）式の誘起電圧Ｅ
が大きくなる。したがって伝送線２０に流れている信号
を抽出する際に、商用周波数ｒ（Ｈｚ）、信号周波数ｆ
ｏ（Ｈｚ）とした場合に各々の磁界による出力電圧をＥ
　（Ｖ）　。 Ｅ、（ｖ）とすると（３）弐より、 Ｅｏ　　　ｆｏ □＝□−−−−−−・・−−−−−−−−−−一−・−
−−−−−一−・−・−・−・−−−−−・・−（４）
ｆ の関係が本質的に成立するので、信号周波数ｆ。 の値を適切な値に選択することによりサーチコイル２１
の誘起電圧に基づいて信号を検出することができ、信号
抽出が可能となる。 また第２図に示すようにサーチコイル２１に並列に並列
共振条件となるコンデンサ２３を付加すれば、必要な信
号周波数の電圧のみを強調して取り出せることになる。 この時の共振周波数ｆは次式で表される。 第３図は伝送線の周囲の磁界中にサーチコイルを設置す
るための一実施例を示すものであり、伝送線２０に引っ
掛けられる部分を有する支持体２４を絶縁物で構成し、
この支持体２４の内部にサーチコイル２１と強磁性体２
２を埋設したものである。このような構成とすれば伝送
線の任意の箇所において支持体２４を引っ掛けるだけで
信号を抽出することができる。FIG. 1 shows a system configuration diagram for realizing a 1:N data transmission method according to the present invention. In the figure, 11
is the parent station, 12. ~12N is a slave station, 13 is a transmission line, 14.
14. ~14N is a transmitting circuit, 15.15. ~15N is a current injection means, 16,161~16. is a receiving circuit, 17.
17°~17,4 is a current detection element, 18.181~18
, are switching elements, 19, to 19. indicates the controlled object. In such a configuration, each slave station 12. ~12. is assigned a unique address, and is configured so that only the slave stations addressed by the master station respond. Further, current transformers or the like are used as the current injection means 15.151 to 15N, and the current detection elements 17.17. 17, a search coil, a Hall effect element, or the like, which can detect the current without contacting the transmission path, is used. In the system shown in Figure 1, the switching elements 18.181-18
, is a normally closed contact, and by short-circuiting each current injection means, the transmission line 13 is formed into a ring shape. Next, as an example of data transmission in this system, an explanation will be given of the operation when the master station 11 issues a command and the called slave station (according to the address information included in the command) sends back a response. First, the master station 11 operates the switching element 18 to open the current injection means 1 just before issuing a command.
The injection end of No. 5 is connected to the transmission line 13. At this time, each slave station 12. ~12° switching elements 18+~18s are in the closed state. Therefore, a current signal injected into the transmission line 13 from the current injection means 15 in accordance with data (address information and operation command of the slave station) from the transmission circuit 14 of the master station 11 flows through the transmission line 13. The current signal flowing through the transmission line 13 is transmitted to the current detection element 17 of each slave station 121-128. ~17H is detected without contact, and is decoded by receiving circuits 16+~16N. The slave station that has been called (selected) by this detected current signal operates the controlled objects (191 to 19N) in accordance with the command given by this current signal. Immediately after the transmission ends, the master station 11 closes the switching element 18 and becomes ready for reception. On the other hand, the slave station that received the call and completed the operation of the controlled object (for example, slave station 12+)
is the same procedure as the master station, first switching element 18. Current injection means 15. is set in the open state. The injection end of is connected to the transmission line 13. At this time, the switching element 18 of the master station 11 and the slave station 12! ~
12. Opening/closing elements 18□-18. is in a closed state. Next, current injection means 15. A current signal is injected into the transmission line 13. The injected current signal is transmitted to the master station 11 and slave stations 122 to 1.
It is detected by 2N current detection elements 17°17□-17N and decoded by receiving circuits 16.16□-16N. Immediately after the transmission of the response signal is completed, the slave station 12+ closes the switching element 181 and enters the receiving state. By repeating the above operations, the master station 11 sequentially sends the slave stations 12
+ ""12N is selected, one master station 11 and N slave stations 12. ~12. Data is transmitted between the two, and one-to-N remote monitoring and control is performed. An example of the current detection means is a search coil, and the principle of detection using the search coil will be described below. FIG. 2 shows the relative positional relationship between the transmission line and the search coil. In the figure, 20 is a transmission line, 21 is a search coil, and 22 is a ferromagnetic material. In Fig. 2, assuming that a frequency r (Hx) and a current I (A) are flowing from the front to the back of the paper, the magnetic field H at a distance r (m) to the search coil 21 is determined by the ampere circuit law. From, H= −(AT/m) −−−−−−−−−・・−
・−・−・・−(1) 2 π r . Therefore, the magnetic flux density B-μH (w b /m2)
Therefore, if the radius of the search coil 21 is a (m), then
The total number of magnetic fluxes Φ is as follows: Φ=π・a2 ・B=π・a2 ・μH■. Therefore, the voltage E induced in the search coil 21 becomes as follows, assuming that the number of turns of the search coil 21 is N. When the search coil 21 is wound around a ferromagnetic material 22, a phenomenon in which magnetic flux is attracted to the ferromagnetic material 22 occurs, so that the induced voltage E in equation (3) is lower than in the case of an air-core coil.
becomes larger. Therefore, when extracting the signal flowing through the transmission line 20, the commercial frequency r (Hz), the signal frequency f
o (Hz), the output voltage due to each magnetic field is E
(V). E, (v) then (3) From 2, Eo fo □=□−−−−−−・・−−−−−−−−−−1−・−
−−−−−1−・−・−・−・−−−−−・・−(4)
Since the relationship f essentially holds, the signal frequency f. By selecting an appropriate value for the search coil 21
It is possible to detect a signal based on the induced voltage of , and signal extraction becomes possible. Further, as shown in FIG. 2, if a capacitor 23 is added in parallel to the search coil 21 to provide a parallel resonance condition, only the voltage of the necessary signal frequency can be extracted with emphasis. The resonance frequency f at this time is expressed by the following equation. FIG. 3 shows an embodiment for installing a search coil in a magnetic field around a transmission line, in which a support 24 having a portion hooked to the transmission line 20 is made of an insulator,
A search coil 21 and a ferromagnetic material 2 are provided inside this support 24.
2 was buried. With such a configuration, signals can be extracted simply by hooking the support 24 at any location on the transmission line.

【発明の効果】【Effect of the invention】

本発明によれば、電流注入電流検出方式としたことによ
り、 （１）伝送路と電流検出素子との結合が極めて疎の状態
で信号検出が可能となる。即ち、伝送路と電流検出素子
が極めて高いインピーダンスを介して接続されているの
と等価になる。 （２）受信動作中の局の電流注入手段（変流器等）の伝
送路への注入端を短絡することが可能となる。 以上の結果、送信動作中の局の送信端から見た伝送路の
インピーダンスは設置局舎数には無関係にほぼ一定とな
り、かつ受信動作中の局の注入端は短絡されているので
送信電力の損失も極めて小さくすることができる。According to the present invention, by using the current injection current detection method, (1) signal detection is possible in a state where the coupling between the transmission line and the current detection element is extremely loose. In other words, this is equivalent to connecting the transmission line and the current detection element through an extremely high impedance. (2) It becomes possible to short-circuit the injection end of the current injection means (current transformer, etc.) to the transmission path of the station during reception operation. As a result of the above, the impedance of the transmission path as seen from the transmitting end of a station in transmitting operation is almost constant regardless of the number of installed stations, and since the injection end of a station in receiving operation is short-circuited, the transmitting power is Losses can also be made extremely small.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明によるデータ伝送方式を実現するための
システム構成図、第２図は伝送線とサーチコイルの相対
位置関係を示す図、第３図は伝送線にサーチコイルを設
置するための実施例を示す図、第４図は従来のシステム
構成図を示している。 １１−　　親局、１２．〜１２Ｎ−・子局、１３−・伝
送路、１４．１４．〜１４Ｎ　　−・−送信回路、１５
．１５．〜１５Ｎ　　・・−・電流注入手段、１６，１
６．〜１６．　　・・・−受信回路、１７．１７１〜１
７Ｎ−・−電流検出素子、１８．１Ｂ、−１８Ｎ　　・
・−開閉素子、１９、〜１９Ｎ＝・制御対象物。 才２図 才３困Fig. 1 is a system configuration diagram for realizing the data transmission method according to the present invention, Fig. 2 is a diagram showing the relative positional relationship between the transmission line and the search coil, and Fig. 3 is a diagram showing the relative positional relationship between the transmission line and the search coil. FIG. 4, which is a diagram showing an embodiment, shows a conventional system configuration diagram. 11- Master station, 12. ~12N-・Slave station, 13-・Transmission line, 14.14. ~14N --- Transmission circuit, 15
．． 15. ~15N --- Current injection means, 16,1
6. ~16. ...-receiving circuit, 17.171~1
7N--Current detection element, 18.1B, -18N ・
・-Switching element, 19, ~19N=・Controlled object. 2 figures, 3 difficulties

Claims (1)

【特許請求の範囲】[Claims] １）１個の親局と複数の子局とを環状の伝送路を介して
接続し、親局と子局との間でデータの送受信を行うよう
にした１：Ｎデータ伝送方式において、親局および各子
局には、送信回路と、前記伝送路に直列挿入された開閉
素子と、該開閉素子に並列接続され、前記送信回路から
の送信データに応じて前記伝送路に電流信号を送出する
電流注入手段と、前記伝送路に流れる電流信号を非接触
で検出する電流検出手段と、該電流検出手段により検出
された電流信号を受信する受信回路とを設け、前記親局
および各子局は送信時のみ自局内の前記開閉素子を開い
て前記電流注入手段により前記伝送路に電流信号を送出
することを特徴とする１：Ｎデータ伝送方式。1) In the 1:N data transmission system, in which one master station and multiple slave stations are connected via a circular transmission path, data is sent and received between the master station and the slave stations. The station and each slave station include a transmitting circuit, a switching element inserted in series in the transmission line, and a switching element connected in parallel to the switching element, which sends a current signal to the transmission line in response to transmission data from the transmitting circuit. A current injection means for detecting a current signal flowing through the transmission path, a current detection means for contactlessly detecting a current signal flowing through the transmission path, and a receiving circuit for receiving the current signal detected by the current detection means are provided. The 1:N data transmission system is characterized in that the switching element in the local station is opened only during transmission, and the current injection means sends out a current signal to the transmission path.
JP27646085A 1985-12-09 1985-12-09 I:n data transmission system Pending JPS62136145A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP27646085A JPS62136145A (en) 1985-12-09 1985-12-09 I:n data transmission system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP27646085A JPS62136145A (en) 1985-12-09 1985-12-09 I:n data transmission system

Publications (1)

Publication Number Publication Date
JPS62136145A true JPS62136145A (en) 1987-06-19

Family

ID=17569749

Family Applications (1)

Application Number Title Priority Date Filing Date
JP27646085A Pending JPS62136145A (en) 1985-12-09 1985-12-09 I:n data transmission system

Country Status (1)

Country Link
JP (1) JPS62136145A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63200644A (en) * 1987-02-16 1988-08-18 Nec Corp Current loop local area network system
US5399965A (en) * 1992-02-21 1995-03-21 Deutsche Itt Industries Gmbh Floating data interface
EP0875995A1 (en) * 1997-04-30 1998-11-04 Siemens Aktiengesellschaft Integrated data transmission circuit with galvanic isolation between input and output
EP1014584A1 (en) * 1997-09-02 2000-06-28 Matsushita Electric Industrial Co., Ltd. Data transmitter

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63200644A (en) * 1987-02-16 1988-08-18 Nec Corp Current loop local area network system
US5399965A (en) * 1992-02-21 1995-03-21 Deutsche Itt Industries Gmbh Floating data interface
EP0875995A1 (en) * 1997-04-30 1998-11-04 Siemens Aktiengesellschaft Integrated data transmission circuit with galvanic isolation between input and output
EP1014584A1 (en) * 1997-09-02 2000-06-28 Matsushita Electric Industrial Co., Ltd. Data transmitter
EP1014584A4 (en) * 1997-09-02 2001-02-07 Matsushita Electric Ind Co Ltd Data transmitter
US6323756B1 (en) 1997-09-02 2001-11-27 Matsushita Electric Industrial Co., Ltd. Data transmitter

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