JPS62183646A - Automatic termination circuit - Google Patents
Automatic termination circuitInfo
- Publication number
- JPS62183646A JPS62183646A JP2633386A JP2633386A JPS62183646A JP S62183646 A JPS62183646 A JP S62183646A JP 2633386 A JP2633386 A JP 2633386A JP 2633386 A JP2633386 A JP 2633386A JP S62183646 A JPS62183646 A JP S62183646A
- Authority
- JP
- Japan
- Prior art keywords
- transmission line
- line
- disconnection
- disconnected
- photocoupler
- 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
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 16
- 230000008054 signal transmission Effects 0.000 claims description 7
- 238000001514 detection method Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 2
- 235000006732 Torreya nucifera Nutrition 0.000 description 1
- 244000111306 Torreya nucifera Species 0.000 description 1
- 239000010902 straw Substances 0.000 description 1
Landscapes
- Dc Digital Transmission (AREA)
- Small-Scale Networks (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は自動終端回路に関し、特にビル設備監視制御装
置、遠方監視制御装置等におけるデータ伝送回路の自動
終端回路に関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic termination circuit, and more particularly to an automatic termination circuit for a data transmission circuit in a building equipment monitoring and control device, a remote monitoring and control device, and the like.
従来、２線直流電流ループによるシリアル信号伝送回路
では、送受４個のフォトカプラにより相互の端局間が絶
縁された直流ループを形成しデータ伝送、および中継を
行なっている。Conventionally, in a serial signal transmission circuit using a two-wire DC current loop, data transmission and relay are performed by forming a DC loop with mutually insulated terminal stations using four transmitting/receiving photocouplers.
第３図は従来の２線直流電流ループによるシリアル信号
伝送回路の構成を示す回路図であり、送受４個のフォト
カプラ、すなわちＳ側受信フォトカプラ１、Ｓ側送信フ
ォトカプラ６、Ｒ側受値フォトカプラフ、Ｒ側送信フォ
トカプラ８により端局相互間が絶縁された状態でオープ
ンコレクタゲート等を介して送信側Ｓ＋、Ｓ−と受信側
Ｒ＋、Ｒ−の間で直流ループを形成しデータ伝送および
中継を行なっている。ここに＋、−は直流ループ流通の
極性を示す。FIG. 3 is a circuit diagram showing the configuration of a serial signal transmission circuit using a conventional two-wire DC current loop, and includes four transmitting and receiving photocouplers: S-side receiving photocoupler 1, S-side transmitting photocoupler 6, and R-side receiving photocoupler. Data is transmitted by forming a DC loop between the transmitting side S+, S- and the receiving side R+, R- via an open collector gate, etc., with the terminal stations insulated by the value photocoupler and the R side transmitting photocoupler 8. and broadcasting. Here, + and - indicate the polarity of DC loop circulation.
上述した従来の２線直流電流ループによるシリアル信号
伝送回路では、第３図に示す如く端局ｎとｎ＋１との間
で、たとえば伝送線９が切断箇所１０で切れた場合を考
えると、端局ｎのＳ端受信フォトカブラ１がオフとなり
、その結果Ｒ端送信フォトカブラ８がオフとなり、以下
同様の動作によって切断箇所１０からセンタ側よりのす
べての端局の信号伝送が不可能となってしまうという欠
点がある。In the conventional serial signal transmission circuit using the two-wire DC current loop described above, for example, if the transmission line 9 is cut at the cut point 10 between terminal stations n and n+1 as shown in FIG. The S-end receiving photocoupler 1 of n is turned off, and as a result, the R-end sending photocoupler 8 is turned off, and the same operation makes it impossible to transmit signals from the cutting point 10 to all terminal stations from the center side. It has the disadvantage of being stored away.
本発明の目的は上述した欠点を除去し、２線直流電流ル
ープによるシリアル信号伝送方式において、電流ループ
を構成する伝送線が切断した場合、受信データの欠落検
出を介して自動的に終端する手段を備えることにより、
全端局のシステムダウンを防止し、切断箇所からセンタ
ー側ではシステム動作を正常に保持しうる自動終端回路
を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks, and to provide means for automatically terminating a serial signal transmission system using a two-wire DC current loop by detecting missing data when the transmission line constituting the current loop is disconnected. By providing
An object of the present invention is to provide an automatic termination circuit that can prevent system failure at all terminal stations and maintain normal system operation from the disconnection point to the center side.
本発明の回路は、２線直流電流ループによるシリアル信
号伝送方式における電流ループを構成する伝送線が切断
した場合に受信データの欠落を検出することによって前
記切断を自動的に検出し終段する手段を備えて構成され
る。The circuit of the present invention is a means for automatically detecting and terminating a disconnection by detecting a drop in received data when a transmission line constituting a current loop in a serial signal transmission system using a two-wire DC current loop is disconnected. It is composed of:
次に図面を参照して本発明の詳細な説明する。Next, the present invention will be described in detail with reference to the drawings.
第１図は本発明の一実施例を示すブロック図である。FIG. 1 is a block diagram showing one embodiment of the present invention.
第１図に点線で示す自動終端回路は、第３図のＳ側受信
ゲート２の出力部、Ｐに付加するものであり、従来の受
信信号ＲＤの代わりに受信信号ＲＤ°を使用することに
よって自動終端を実現している。The automatic termination circuit shown by the dotted line in FIG. 1 is added to the output section P of the S-side receiving gate 2 in FIG. 3, and by using the received signal RD° instead of the conventional received signal RD Achieves automatic termination.
回線１折検出カウンタ３は、伝送路のボーレイ１〜（ｂ
ａ ｕ ｄ ｒ ａ ｔ ｅ ）と同周波数のクロ
ックＣＬ Ｋをカウントする２ｎ分周カウンタで、ｎを
大きくとっておくことにより受信データＲＤが２男ビッ
ト以内にマーク（ｍａｒｋ）状態となるためリセットさ
れ出力Ｑはローレベル（ｌｏｗ １ｅｖｅｌ）を保持
する。The line 1 fold detection counter 3 indicates the baud rate 1 to (b) of the transmission line.
This is a 2n frequency division counter that counts the clock CLK with the same frequency as the clock CLK (a u d r a t e ), and by setting n large, the received data RD will be in the mark state within 2 male bits, so it will be reset. The output Q is held at a low level (low 1 level).
第２図は第１図の実施例における主要信号特性図である
。FIG. 2 is a diagram of main signal characteristics in the embodiment of FIG. 1.
時間ｔにおいて第３図に示す如く伝送線の切断があった
とすると、以後Ｓ ｌ！Ｉｊ受信フォトカブラ１はオフ
となり、受信信号ＲＤはローレベルに保持される。この
状態が２％ビ・ソト以上続くと回線断検出カウンタ３の
Ｑ出力がハイレベル（ｈ ｉ ｇｈｌｅｖｅｌ）となり
、これがカウンタ制御ゲー）・４によってクロックＣＬ
Ｋの入力を禁止するため受信信号ＲＤ はハイレベル
に固定され、オープンコレクタゲート５の出力はオープ
ンとなり、第３図端局ｎからセンター側寄りの伝送路の
動作は正常に保持される。If the transmission line is disconnected at time t as shown in FIG. 3, then S l! The Ij reception photocoupler 1 is turned off, and the reception signal RD is held at a low level. If this state continues for 2% or more, the Q output of the line disconnection detection counter 3 becomes high level (h i glevel), and this causes the clock CL to be set by the counter control game 4.
In order to prohibit the input of K, the received signal RD is fixed at a high level, the output of the open collector gate 5 is opened, and the operation of the transmission path from the terminal station n to the center side in FIG. 3 is maintained normally.
以上説明したように本発明は、伝送線の切断による受信
データの欠落を検出して自動終端する手段を備えること
により、伝送線の切断時にも全端局のシステムダウンを
抑止し、切断箇所からセンター側の部分ではシステム動
作を正常に保持しうる自動終端回路が実現できるという
効果がある。As explained above, the present invention is equipped with means for automatically terminating received data by detecting loss of received data due to transmission line disconnection, thereby preventing system failure at all end stations even when the transmission line is disconnected, The center side part has the effect of realizing an automatic termination circuit that can maintain normal system operation.
第１図は本発明の一実施例を示すブロック図、第２図は
第１図の実施例における主要信号特性図、第３図は従来
の２線直流電流ループによるシリアル信号伝送回路の構
成を示す回路図である。
１・・・・・・Ｓ側受信フォトカプラ、２・・・・・・
Ｓ側受信ゲート、３・・・・・・回線断検出カウンタ、
４・旧・・カウンタ制御ゲート、５・・・・・・オープ
ンコレクタゲート、６・・・・・・Ｓ側送信フォトカプ
ラ、７・・・・・・Ｒ側受信フォトカプラ、８・・・・
・・Ｒ側送信フォトカブラ、９・・・茅 ／Ｉ！１
千り圀
ヤＮ＼−藁Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a main signal characteristic diagram in the embodiment of Fig. 1, and Fig. 3 shows the configuration of a serial signal transmission circuit using a conventional two-wire DC current loop. FIG. 1...S side receiving photocoupler, 2...
S-side receiving gate, 3...Line disconnection detection counter,
4. Old... Counter control gate, 5... Open collector gate, 6... S side transmitting photocoupler, 7... R side receiving photocoupler, 8...・
...R side transmitting photocabra, 9...Kaya /I! 1 Chirikuniya N\-Straw
Claims (1)
る電流ループを構成する伝送線が切断した場合に受信デ
ータの欠落を検出することによって前記切断を自動的に
検出し終端することを特徴とする自動終端回路。An automatic termination circuit characterized in that when a transmission line constituting a current loop in a serial signal transmission method using a two-wire DC current loop is disconnected, the disconnection is automatically detected and terminated by detecting a drop in received data. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2633386A JPS62183646A (en) | 1986-02-07 | 1986-02-07 | Automatic termination circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2633386A JPS62183646A (en) | 1986-02-07 | 1986-02-07 | Automatic termination circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS62183646A true JPS62183646A (en) | 1987-08-12 |
Family
ID=12190500
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2633386A Pending JPS62183646A (en) | 1986-02-07 | 1986-02-07 | Automatic termination circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS62183646A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007278561A (en) * | 2006-04-04 | 2007-10-25 | Tomoe Shokai:Kk | Communication device |
-
1986
- 1986-02-07 JP JP2633386A patent/JPS62183646A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007278561A (en) * | 2006-04-04 | 2007-10-25 | Tomoe Shokai:Kk | Communication device |
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