JP3136020B2 - Multiplex communication method - Google Patents
Multiplex communication methodInfo
- Publication number
- JP3136020B2 JP3136020B2 JP05025544A JP2554493A JP3136020B2 JP 3136020 B2 JP3136020 B2 JP 3136020B2 JP 05025544 A JP05025544 A JP 05025544A JP 2554493 A JP2554493 A JP 2554493A JP 3136020 B2 JP3136020 B2 JP 3136020B2
- Authority
- JP
- Japan
- Prior art keywords
- communication
- current
- constant current
- slaves
- transmission
- 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.)
- Expired - Fee Related
Links
- 238000000034 method Methods 0.000 title description 2
- 230000005540 biological transmission Effects 0.000 claims description 21
- 238000010586 diagram Methods 0.000 description 4
Landscapes
- Small-Scale Networks (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は多重通信（ポーリング通
信）方式に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex communication (polling communication) system.
【０００２】[0002]
【従来の技術】通信マスタに複数の通信スレーブが接続
される多重通信方式においては、通信と各スレーブへの
電源供給の双方を２線の伝送路で行う、いわゆる電源多
重通信方式がある。2. Description of the Related Art In a multiplex communication system in which a plurality of communication slaves are connected to a communication master, there is a so-called power multiplex communication system in which both communication and power supply to each slave are performed via a two-wire transmission path.
【０００３】[0003]
【発明が解決しようとする課題】ところで、従来の電源
多重通信方式では、図４に示すように、定電流源４３が
通信スレーブ４２ａ・・４２ｎへの電源供給と、通信のた
めの電位引上げ（プルアップ）の双方の用途を兼ねる方
式となっており、このため、定電流源４３を小電流源と
した場合、伝送路に接続可能な通信スレーブの数が少数
に限定される。一方、その点を考慮して大電流定電流源
を採用すると、通信マスタ４１あるいは各通信スレーブ
４２ａ・・４２ｎの送信トランジスタT41 もしくはT42a・・
T42nのコレクタ電流が増加し、このため定格値の大きい
トランジスタを使用する必要があって、大型化やコスト
アップをもたらす要因となる。また、通信路の短絡事故
等も考慮すれば無制限に大電流を用いることもできな
い。In the conventional power multiplex communication system, as shown in FIG. 4, the constant current source 43 supplies power to the communication slaves 42a, 42n, and raises the potential for communication (see FIG. 4). (Pull-up). Therefore, when the constant current source 43 is a small current source, the number of communication slaves that can be connected to the transmission line is limited to a small number. On the other hand, if a large current constant current source is adopted in consideration of this point, the transmission transistor T41 or T42a of the communication master 41 or each of the communication slaves 42a.
The collector current of T42n increases, so that it is necessary to use a transistor with a large rating value, which causes an increase in size and cost. In addition, a large current cannot be used indefinitely in consideration of a short circuit accident in a communication path.
【０００４】本発明はそのような事情に鑑みてなされた
もので、その目的とするところは、通信マスタに多数の
通信スレーブを接続しても、そのマスタおよび各スレー
ブの送信トランジスタの定格値が小さいものを使用でき
る電源多重通信方式を提供することにある。The present invention has been made in view of such circumstances, and an object of the present invention is to provide a communication master having a large number of communication slaves connected to a communication master, and having the rated values of the transmission transistors of the master and slaves. It is an object of the present invention to provide a power multiplex communication system that can use a small-sized one.
【０００５】[0005]
【課題を解決するための手段】上記の目的を達成するた
め、本発明は、通信マスタに複数の通信スレーブが接続
され、その各通信スレーブへの電源供給と通信の双方
を、２線の伝送路を通じて行う通信方式において、実施
例に対応する図１に示すように、電流の大きさが互いに
異なる二種の定電流源３ａ，３ｂと、それらの定電流源
３ａ，３ｂの伝送路Ｌへの接続状態の変更により、伝送
路Ｌへの供給電流の大きさを、大電流もしくは小電流の
いずれかに選択的に切り換えるための手段（例えば切り
換えスイッチ４）を備え、伝送路Ｌへの供給電流の大き
さを、通信時には小電流とし、非通信時には大電流とす
るように構成されていることによって特徴づけられる。According to the present invention, a plurality of communication slaves are connected to a communication master, and both power supply and communication to each communication slave are performed by two-wire transmission. In a communication method performed through a path, as shown in FIG. 1 corresponding to the embodiment, two types of constant current sources 3a and 3b having different current magnitudes and a transmission path L of the constant current sources 3a and 3b are connected. Is provided with means (for example, a changeover switch 4) for selectively switching the magnitude of the current supplied to the transmission line L to either a large current or a small current by changing the connection state of the transmission line L. It is characterized in that the magnitude of the current is configured to be a small current during communication and a large current during non-communication.
【０００６】[0006]
【作用】図２のタイムチャートに示すように、通信時す
なわち送信トランジスタＴ1 ，Ｔ2 の操作によって通信
回路の断続を行うときには、スイッチ４の操作により供
給電流の大きさを小電流とすることで、送信トランジス
タＴ1 ，Ｔ2 のコレクタ電流を低く抑えることができ
る。一方、非通信時にはスイッチ４を切り換え、大電流
を供給することによって、一つの通信マスタ１に対して
多数の通信スレーブ２ａ・・２ｎを接続することが可能に
なる。As shown in the time chart of FIG. 2, at the time of communication, that is, when the communication circuit is interrupted by operating the transmission transistors T1 and T2, the magnitude of the supply current is reduced by operating the switch 4, The collector currents of the transmission transistors T1 and T2 can be kept low. On the other hand, by switching the switch 4 during non-communication and supplying a large current, it is possible to connect a large number of communication slaves 2a to 2n to one communication master 1.
【０００７】[0007]
【実施例】図１は本発明の通信方式の実施例のシステム
構成図である。この通信システムは、通信マスタ１に、
多数の通信スレーブ２ａ・・２ｎが接続され、その各通信
スレーブ２ａ・・２ｎへの電源供給と通信の双方を、２線
の伝送路で行う電源多重方式で、通信時においては、CO
MMラインＬが、後述する定電流源３ｂによるプルアップ
によって、常時は「Ｈ」レベルに設定され、通信マスタ
１側の送信トランジスタＴ1 の駆動による回路の断続に
よって、データを各通信スレーブ２ａ・・２ｎに送出す
る。FIG. 1 is a system configuration diagram of a communication system according to an embodiment of the present invention. In this communication system, a communication master 1
A large number of communication slaves 2a... 2n are connected, and both power supply and communication to each communication slave 2a.
The MM line L is always set to "H" level by a pull-up by a constant current source 3b described later, and data is transmitted to each communication slave 2a,. 2n.
【０００８】また、各通信スレーブ側からデータを送信
するときには、それらの各通信スレーブ２ａ・・２ｎ側
で、送信トランジスタＴ2 の駆動により回路接続をONと
することでデータを通信マスタ１に送信する。When data is transmitted from the communication slaves, the data is transmitted to the communication master 1 by turning on the circuit connection by driving the transmission transistor T2 on each of the communication slaves 2a... 2n. .
【０００９】さて、本発明実施例では、定電流源として
大電流定電流源３ａと小電流定電流源３ｂを備えてお
り、それら二つの定電流源３ａ，３ｂは伝送路のCOMMラ
インＬに電源切り換え用のスイッチ４を介して互いに並
列に接続されている。In the embodiment of the present invention, a large current constant current source 3a and a small current constant current source 3b are provided as constant current sources, and these two constant current sources 3a and 3b are connected to the COMM line L of the transmission line. They are connected in parallel with each other via a power supply switch 4.
【００１０】そして、この種の多重通信（ポーリング通
信）においては、通信が通信マスタ１側で管理されるこ
とから、先のスイッチ４の切り換え操作は通信マスタ１
側で行われ、図２のタイムチャートに示すように、通信
時においては、小電流定電流源３ｂがCOMMラインＬに接
続され、この定電流源３ｂの電位で通信のための電位引
上げが行われる。一方、非通信時には、COMMラインＬへ
の接続が大電流定電流源３ａに切り換わり、各通信スレ
ーブ２ａ・・２ｎへの電源供給が行われる。In this type of multiplex communication (polling communication), since the communication is managed by the communication master 1, the switching operation of the switch 4 is performed by the communication master 1.
As shown in the time chart of FIG. 2, during communication, the small current constant current source 3b is connected to the COMM line L, and the potential of the constant current source 3b raises the potential for communication. Is On the other hand, during non-communication, the connection to the COMM line L is switched to the large current constant current source 3a, and power is supplied to each of the communication slaves 2a,.
【００１１】従って、通信マスタ１の送信トランジスタ
Ｔ1 あるいは各通信スレーブ２ａ・・２ｎの送信トランジ
スタＴ2 のコレクタ電流の定格値は、小電流定電流源３
ｂの電流値に耐え得る程度の大きさで済む。Therefore, the rated value of the collector current of the transmitting transistor T1 of the communication master 1 or the transmitting transistor T2 of each of the communication slaves 2a,.
The size may be large enough to withstand the current value of b.
【００１２】なお、以上の実施例では、大電流定電流源
３ａもしくは小電流定電流源３ｂのいずれか一方を、CO
MMラインＬに選択的に接続する構成としているが、この
ほか例えば図３に示すように、小電流定電流源３３ｂは
スイッチ等を介せずにCOMMラインＬに直接に接続し、ま
た、大電流定電流源３３ａは開閉スイッチ３４を介して
接続しておき、そのスイッチ３４の開閉制御によって、
COMMラインＬに、大電流と小電流定電流源３３ａと３３
ｂの双方を接続するか、もしくは小電流定電流源３３ｂ
のみを接続するのいずれか一方の接続を行うように構成
してもよい。In the above embodiment, either the large current constant current source 3a or the small current constant current source 3b is
Although it is configured to be selectively connected to the MM line L, in addition to this, as shown in FIG. 3, for example, the small current constant current source 33b is directly connected to the COMM line L without using a switch or the like. The current constant current source 33a is connected via an open / close switch 34, and the open / close control of the switch 34
In the COMM line L, the large current and small current constant current sources 33a and 33
b or a small current constant current source 33b
Only one of the connections may be made.
【００１３】さらに、電源供給用の定電流源の回路構成
は、上記した二つの例に限られることなく、COMMライン
Ｌへの電源供給の大きさを、大電流もしくは小電流のい
ずれか一方に選択的に切り換えれるものであれば、他の
一般的な回路手段に代替可能である。Further, the circuit configuration of the constant current source for supplying power is not limited to the above two examples, and the magnitude of power supply to the COMM line L can be changed to either a large current or a small current. If it can be selectively switched, it can be replaced with other general circuit means.
【００１４】[0014]
【発明の効果】以上説明したように本発明の通信方式に
よれば、定電流源として電流の大きさが互いに異なる二
種の定電流源を設け、それらの定電流源の上記伝送路へ
の接続状態の変更により、２線の伝送路への供給電流の
大きさを大電流もしくは小電流のいずれかに選択的に切
り換えるように構成したので、電源供給を電流の大きさ
を、通信時には小さく、また非通信時には大きくするこ
とができ、これによって通信マスタに多数の通信スレー
ブを接続する場合であっても、通信マスタおよび通信ス
レーブの送信トランジスタとして、定格コレクタ電流値
が小さいものを使用でき、その結果としてシステムの小
型化および低コスト化を達成できる。As described above, according to the communication system of the present invention, two types of constant current sources having different current magnitudes are provided as constant current sources, and these constant current sources are connected to the transmission line. By changing the connection state, the magnitude of the current supplied to the two-wire transmission line is selectively switched to either a large current or a small current. In addition, it can be increased during non-communication, so that even when a large number of communication slaves are connected to the communication master, a transistor having a small rated collector current value can be used as a transmission transistor of the communication master and the communication slave, As a result, the size and cost of the system can be reduced.
【図１】本発明実施例のシステム構成図FIG. 1 is a system configuration diagram of an embodiment of the present invention.
【図２】その実施例の電源切り換えの動作を示すタイム
チャートFIG. 2 is a time chart showing a power supply switching operation of the embodiment.
【図３】本発明の他の実施例の定電流源の回路構成図FIG. 3 is a circuit configuration diagram of a constant current source according to another embodiment of the present invention.
【図４】電源多重通信の従来のシステム構成例を示す図FIG. 4 is a diagram showing an example of a conventional system configuration of power multiplex communication.
１・・・・通信マスタ Ｔ1・・・・ 送信トランジスタ ２ａ・・２ｎ・・・・通信スレーブ Ｔ2a・・・・送信トランジスタ ３ａ・・・・大電流定電流源 ３ｂ・・・・小電流定電流源 ４・・・・スイッチ（電源切り換え用） 1 communication master T1 transmission transistor 2a 2n communication slave T2a transmission transistor 3a large current constant current source 3b small current constant current Source 4 Switch (for switching power supply)
Claims (1)
され、その各通信スレーブへの電源供給と通信の双方
を、２線の伝送路を通じて行う通信方式において、電流
の大きさが互いに異なる二種の定電流源と、それらの定
電流源の上記伝送路への接続状態の変更により、当該伝
送路への供給電流の大きさを、大電流もしくは小電流の
いずれかに選択的に切り換えるための手段を備え、伝送
路への供給電流の大きさを、通信時には小電流とし、非
通信時には大電流とするように構成されていることを特
徴とする多重通信方式。1. A communication system in which a plurality of communication slaves are connected to a communication master, and both power supply and communication to each communication slave are performed through a two-wire transmission path. Constant current sources, and by changing the connection state of those constant current sources to the transmission line, to selectively switch the magnitude of the current supplied to the transmission line to either a large current or a small current. Equipped with means , transmission
The amount of current supplied to the
A multiplex communication system characterized in that a large current is used during communication.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05025544A JP3136020B2 (en) | 1993-02-15 | 1993-02-15 | Multiplex communication method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05025544A JP3136020B2 (en) | 1993-02-15 | 1993-02-15 | Multiplex communication method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06244851A JPH06244851A (en) | 1994-09-02 |
| JP3136020B2 true JP3136020B2 (en) | 2001-02-19 |
Family
ID=12168931
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05025544A Expired - Fee Related JP3136020B2 (en) | 1993-02-15 | 1993-02-15 | Multiplex communication method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3136020B2 (en) |
-
1993
- 1993-02-15 JP JP05025544A patent/JP3136020B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06244851A (en) | 1994-09-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |