JPH0797774B2 - Circuit switching loop network status signal transmission system - Google Patents

Description

The present invention relates to a circuit switched loop network, and more particularly to a circuit switched loop network in which a plurality of general purpose interface buses (hereinafter abbreviated as GP-IB) are connected. The present invention relates to a status signal transmission system.

[Prior Art] GP-IB is currently widely used for transmission between measuring devices. However, GP-IB has a problem that the transmission distance can be extended up to about 20 m, and in order to solve this, as shown in Fig. 3, the GP-IB is divided into a plurality of GP-IBs.
Each node station 12a, 12 of the circuit switching loop network in which IBa, GP-IBb, GP-IBc are connected by the loop transmission line 13.
A method of connecting to b and 12c is considered. In addition, 14a, 14
b, 14c, 14d, 14e and 14f are terminals connected to each GP-IBa, GP-IBb and GP-IBc, and 11 is a central control station.

Here, GP-IB has ATN (Attention), SRQ (Service
request), IFC (Interfaec clear), REN (Remote enabl
There are five status signals, e) and EOI (End or identify).
In normal GP-IB, these signals are commonly connected between each device, and there is no problem in their transmission, but when GP-IB is separated as shown in FIG. , GP-
It is necessary to transmit the information of the status signal between IBs.

Of the five status signals, ATN, IFC, and REN are controller outputs, and SRQ and EOI are talker outputs. However, multiple talkers can exist in the system, and if path control is considered, the controller It may be possible to change, and it cannot be clarified in Fig. 3 which GP-IB outputs a status signal. For example, ATN
Regarding signals, GP-IBa may send to other GP-IBb and GP-IBc in some cases, and GP-IBb may be the sender in some cases. Therefore, conventionally, it is difficult to secure a dedicated area for status signal transmission, and the transmission has been performed by communication between the node stations via software.

FIG. 4 shows a procedure of transmitting a status signal when the conventional communication between node stations is used. Now, when the ATN signal of GP-IBa changes from "High" to "Low", the node station 12a detects it and sends the information of ATN "Low" to the central control station 11. In response to this, the central control station 11 receives the AT
A control command to change the N signal to “Low” is sent to the node stations 12b and 12c, and each node station 12b,
In response to this, 12c changes the ATN signal from "High" to "Low".

[Problems to be solved by the invention] However, the communication between the node stations is not used only for the transmission of the status signal, so only the information that the ATN signal becomes "Low" is sent. However, since it is necessary to add an address, a code, etc., the amount of information becomes considerable. In addition, processing of such information is all software processing, which takes a considerable amount of time.

For communication between the node stations, generally, an area common to each node is used without providing a dedicated area for the node stations 12a to 12b. Therefore, from node station 12a to node station 12b
Data cannot be sent directly to the central control station.
It will be done through 11, which causes more time.

Even if you just send the information that the ATN signal is "Low",
If the communication between node stations is used, in the worst case, it takes time in seconds, which is an obstacle to high-speed transmission in GP-IB.

An object of the present invention is to configure a circuit switching loop network that circulates a transmission frame at a constant speed on a loop transmission line in which a plurality of node stations are sequentially connected, and divide GP-IB into a plurality to divide each of the circuit switching loop networks. In a circuit-switched loop network that is connected to a node station to perform data transmission between each GP-IB, the above-mentioned drawbacks of the prior art are solved, and GP-IB is divided between GP-IBs divided by the circuit-switched loop network. It is an object of the present invention to provide a new state signal transmission method for a circuit switching loop network capable of rapidly transmitting the state signal.

[Means for Solving Problems] The gist of the present invention is to provide an attention signal which is a status signal of a general-purpose interface, a service request signal, an interface clear signal, a remote enable signal, an end signal.
A bit station for transmitting a status signal for transmitting an OR identify signal is provided in the transmission frame one bit each, and the node station where the status signal of the connected general-purpose interface bus has changed is the bit for transmitting the status signal. The changed status signal information is written to the area, and the other node stations detect the change of the status signal transmission bit in the transmission frame and write the changed status signal information to the general-purpose interface bus connected to the own node station. To send.

[Operation] A bit area for GP-IB status signal transmission is dedicated to each bit on the transmission frame, and each node station connected to GP-IB changes the status of the signal on its own bus. Then write that information into that bit,
Since it is transmitted to the receiving side, changes in the status signal are transmitted to other GP-IB while the transmission frame goes around the loop transmission line.
Can be communicated to without passing through the central control station.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 2 shows an example of the structure of a GP-IB transmission frame. In the transmission frame 31 which circulates the loop transmission line (FIG. 3), areas for ATN, SRQ, IFN, REN, and EOI status signal transmission are provided one bit at a time. Here, it is assumed that only the node station in which the state of the corresponding signal of the connected GP-IB has changed has the transmission right for each bit. Therefore, normally, the bit for transmitting the state signal circulates around the loop transmission line 13 while maintaining the previous state.

Fig. 1 shows an example of the GP-IB transmission procedure. Now GP-IBa, GP-
When the ATN signal of both IBb and GP-IBc is "Hign" and the ATN bit in the transmission frame 31 is "1", the AT of GP-IBa is AT
It is assumed that the N signal has changed to "Low". At this time, the node station 12a detects this change, and the transmission frame 3
Write 0 to the ATN bit in 1. On the other hand, the other node stations 12b, 12c constantly monitor the status signal transmission bits, detect that the ATN bit has changed from "1" to "0", and detect the respective GP-IBb, GP -Send the ATN signal "Low" to IBc. After that, GP-IBa, GP-IBb, GP-
For both IBc, the ATN signal is "Low" and the ATN bit is "0".

As described above, according to this embodiment, the change in the status signal of GP-IB is detected only by judging whether the status signal transmission bit in the transmission frame is "0" to "1". Information transmission by complicated and time-consuming software processing such as a change in the status signal is eliminated, and the amount of information required for software processing is small.

In addition, since the transmission frame is provided with a dedicated area for transmitting each status signal, and the node station constantly monitors these status signal transmission bits, when a change in the status signal occurs, the status signal is immediately transmitted. Therefore, the status signal is not transmitted through the central control station, and the transmission of the status signal does not take time due to the central control station.

Therefore, it is possible to speed up the status signal when the GP-IB is divided and expanded by the circuit switching loop.

[Effects of the Invention] According to the present invention, it is possible to transmit a change in a status signal between GP-IBs divided by a circuit-switched loop network to another GP-IB while a transmission frame goes around a loop transmission line. Therefore, the GP-IB status signal can be quickly transmitted between GP-IB.

[Brief description of drawings]

FIG. 1 shows the transmission procedure of the GP-IB status signal according to the present invention by ATN.
FIG. 2 is a signal sequence diagram described by taking the case of the signal “Low” as an example, FIG. 2 is a configuration diagram illustrating an example of a transmission frame of GP-IB according to the present invention, and FIG. 3 is a plurality of GP-IBs in a circuit switching loop network. FIG. 4 is a signal sequence diagram for explaining an example of the conventional GP-IB status signal transmission procedure when the ATN signal is “Low”. In the figure, 11 is a central control station, 12a to 12c are node stations, 13 is a loop transmission line, 14a to 14f are GP-IB terminals, 31 is a transmission frame, GP-IBa, GP-IBb, GP-IBc are general-purpose interfaces. It's a bus.

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Claims (1)

[Claims] 1. A circuit switching loop network that circulates a transmission frame at a constant speed on a loop transmission line in which a plurality of node stations are sequentially connected, and a general-purpose interface bus is divided into a plurality of node stations of the circuit loop network. In a circuit-switched loop network in which data is transmitted between general-purpose interface buses by connecting to a general-purpose interface bus, attention signals, service request signals, interface clear signals, remote enable signals, end-or-identify signals, which are status signals of general-purpose interfaces, are used. A bit region for transmitting a state signal for transmitting a signal is provided in the transmission frame, one bit each, and the node station in which the state signal of the connected general-purpose interface bus has changed is the bit region for transmitting the state signal. The changed status signal information is written to other node stations, and the changed status signal information is sent to the general-purpose interface bus connected to the local node station by detecting the change in the status signal transmission bit in the transmission frame. A state signal transmission method for a circuit loop network characterized by: