JPS645785B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling data transmission and reception in loop transmission using a serial transmission path.

FIG. 1 shows an example of a loop transmission configuration. Stations 1, 2, 3, and 4 are connected in a loop through transmission lines 10a to 10d.
Each station has a computer 5 and an input/output device 6.
~8 are connected. This system assumes that data can be sent from any station to any station. In loop transmission, only one station can transmit at the same time, so prior to data transmission, priority control of transmission rights is required to select only one of the stations requesting transmission.
An example of a conventional priority control method will be described next.

To select the station with the transmission request,
It is necessary to send a signal at some station to allow acquisition of transmission rights. That is, in FIG. 2, station 1 is downstream as shown in 2A.
Send POL pattern. POL pattern is 3rd
As shown in the figure, these are special signals for the SYNC pattern and POL pattern for synchronization. When there is a transmission request at station 3, this station changes the transmission right acquisition permission signal to a transmission right acquired signal. That is, the POL pattern is changed to the RSV pattern.
This pattern is a special signal of the SYNC pattern and RSV pattern for synchronization as shown in FIG. After this signal, station 3
Send the data downstream as in B. Data is the third
As shown in the figure, synchronization flags, destination addresses, control information, data contents, error check information, etc. are included before and after. Even if a transmission request is made at station 4, the transmission right cannot be acquired because the RSV pattern has already been established. Next, a conventional method (polling rotation method) in which transmission rights are sequentially granted to stations that have a transmission request will be described.

In Figure 4, the function of station 1 is fixed as a control station, and the POL signal is always sent from this station to control other stations 2 to 4.
This figure shows a method for granting transmission rights to. That is, station 1 first sends a POL, and station 3, which has a transmission request, sends this POL.
Convert to RSV and obtain transmission rights. Then send the data and mark the end of the data after the data
Add END pattern. After control station 1 detects this END, it again sends POL to hand over the transmission right to another station. Repeat this thereafter. FIG. 6 shows a time chart of the above operation. The horizontal axis represents time, and the vertical axis represents station position. The upper part of the time axis of each station represents received data, and the lower part represents transmitted data.

In this method, after the data, the control station 1 needs to recognize the end of the data.
A special pattern called END is required, and
It is inefficient because the POL for soliciting the next transmission right is sent out after reaching the control station once. Furthermore, the control station is required to control the transmission rights evenly to each station. In order to eliminate the above drawbacks, there is a method shown in FIG.

FIG. 5 shows a system in which the functions of the control station explained in FIG. 4 are sequentially transferred to each of the stations 1 to 4. Initially, station 1 becomes the control station and sends out POL. Station 3 with the transmission request sends POL
Change to RSV and continue sending data. When the data transmission is finished, this station 3 becomes a control station and subsequently transmits a POL requesting the next transmission right. Similarly,
A feature of this system is that stations that have completed transmission become control stations one after another. Figure 7 shows a time chart of this method. It is thought that this method directly replaces the END pattern in Figure 6 with the POL pattern. Furthermore, since the station that completes transmission immediately sends out POL, there is a possibility that each station can obtain the transmission right in turn, and the efficiency is also better than that of FIG. 4. However, if this station also does not receive a transmission request, the POL will go around the transmission path and return to the station that sent the POL, so if a POL is detected, a control circuit, a POL counter, and a timer will be required to send the POL again. etc. must be provided at each station, which has the disadvantage of complicating the hardware.

An object of the present invention is to provide a loop-type data transmission control device that does not lose the high efficiency of the conventional polling system, reduces the hardware of each station, and leaves integrated control to the control station. be.

The present invention focuses on the high efficiency of the conventional fixed control station integrated control system and the polling rotation system, and combines both methods, and uses the polling rotation system to control the hardware of stations other than the control station. This is a simplified version of the hardware.

The present invention will be explained in detail below. FIG. 8 is a conceptual explanatory diagram of the present invention. 8A→8B→8C→8D indicates the order of occurrence. Station 1 and ST1 are control stations, and ST2 to ST4 are other stations. ST1 has two new functions not seen before. First, the transmission right acquisition permission signal (POL) sent by a station other than this station ST1 is unconditionally changed into a transmission right acquired signal (RSV) and transmitted, and the RSV
The second function is to send a transmission right acquisition permission signal (POL) following this, and the second function is to transmit a transmission right acquisition permission signal (POL) if the transmission right acquisition permission signal (POL) sent by the ST1 itself returns to the ST1. This function sends a permission acquisition signal (POL). By adding these two functions, stations other than control station ST1 can
Self added it to the data and sent it as the sender.
You will not receive the POL again, and instead you will receive this
Receive RSV converted by ST1 instead of POL. As a result, the receiving station is switched from the sending mode to the pass mode (repeat mode). On the other hand, stations other than the control station do not require the conventional POL monitoring function. That is, only the control station needs to have the POL monitoring function. here,
The POL monitoring function checks whether the time from one POL to the next POL corresponds to the normal time.If POL is received continuously, the number of times it is received is the standard value. The purpose is to check whether it is within the range. The former is played by a timer for detecting timeout, and the latter is played by a timer for detecting timeout.
Count POL detection circuit from POL detection circuit
The POL counting counter plays this role. however,
The timer and counter may be realized not only by hardware but also by software (firmware) based on a microprogram.

Next, the operation will be explained in accordance with the configuration shown in FIG. FIG. 9 is an example of the time chart. When station ST1 sends out a POL, this POL is
It is sent downstream in the order of 1→ST2→ST3→...
Now, if ST3 has a transmission request, the ST3 will
After converting POL to RSV, add data and send it,
After transmission is complete, add POL and send. This ST
If you return to ST1 while keeping the sending format from 3, ST1 will suck in the RSV in the first area,
The next data is passed through as is, and for the POL in the last area, the POL is unconditionally RSV
Instead, the above data is sent continuously. Furthermore, following the RSV transmission, a new POL is transmitted. Through this POL, the transmission right is once again given to the transmission requesting station. In Figure 9, ST
A case is shown in which ST2 has a transmission request as a new transmitting station, and the above POL is taken in by ST2 and becomes RSV and data addition,
This means that ST2 has acquired the transmission right. On the other hand, ST3
The RSV that is unconditionally changed from the data and POL sent to ST1 from ST2 is ST
Go to 3. ST3 sucks in this data and receives RSV. By receiving this RSV, ST3
ends the data sending mode and changes to pass (repeat) mode.

Note that there are cases where a POL generated from ST1 returns to ST1 without any response through the line. Either there is no transmission request at each station, or even if there is a transmission request, the station is unable to receive POL for some reason (mainly failure). In response to this return of POL, ST1 sends POL onto the line again. In order to monitor the time it takes for the POL to return and to monitor the number of times the POL returns, ST1
performs POL monitoring using a timer and counter.

FIG. 10 shows an embodiment of the control station ST1, and FIG. 11 shows an embodiment of another station. Control station ST1 has 11 receiving circuits (RSV) and 1 transmitting circuit (TRM)
2. Re-synchronization circuit 13, demodulation circuit 14, clock recovery circuit 15, modulation circuit 16, selector 17, shift register 18, POL detection circuit 19, RSV detection circuit 20, selector 21, RSV pattern generator 22, POL pattern generator 23,
control circuit 24, reception units 25, 26, timer 28,
It consists of a counter 27. Timer 28 and counter 2
7 is provided for POL monitoring. Reception department 2
Although not shown, the transmission request to the control station 5, the transmission completion notification to the reception unit 26, the network configuration control to the control circuit 24, and the transmission data to the selector 21 are transmitted from a computer connected to the control station. Given. Additionally, information such as data sent via a transmission path is taken into this computer as necessary.

In the control station having such a configuration, data inputted into the shift register 18 through the receiver 11 and the demodulation circuit 14 is sent to the POL detection circuit 19,
The RSV detection circuit 20 moves the selectors 17 and 21 via the control circuit 24. The selector 21 is for selecting one of transmission data, RSV pattern, and POL pattern. Selector 17 repeats the received data as is (repeat mode)
This is a switch between sending data from the own station (transmission mode). The reception unit 25 is a circuit that notifies the transmission request, and the reception unit 26 is a circuit that notifies the control circuit 24 of the completion of transmission. When POL is detected as shown in FIG. 10 as a block characterizing the control station, the POL monitoring timer 28 and POL counter 27 are activated based on the detection result. The timer 28 determines whether or not the time from one POL to receiving the next POL is longer than a reference time serving as a reference for abnormality determination, and when the time is greater, generates a timeout over output. POL counter 27 is
The number of POLs is counted and sent to the control circuit 24. The control circuit 24 determines that there is an abnormality in the line or the like when the number of consecutively received POLs is greater than a reference value indicating a normal value, and performs necessary control. Furthermore,
When the station itself returns the POL it sent out, it sends out the POL from the POL pattern generator 23 again onto the line via the selector 21. Also, there is a response from another station and RSV-data-
When receiving a POL, the RSV pattern generator 22 instead absorbs the POL.
The RSV is sent out onto the line via the selector 21.
Continue with POL of POL pattern generator 23
is sent onto the line via the selector 21. As a result, when a control station receives a response from another station and a POL is attached, the POL is always replaced with RSV, and then the POL issued by the control station is added and sent. Become. This allows other stations to
There is no need to receive POL again, and the POL reception interval check function is unnecessary.

The stations other than the control station in FIG. 11 have substantially the same configuration as the control station in FIG. 10, and the same symbols indicate the same contents. Further, while this station has a control circuit 29, it does not require a timer 28 or a counter 27. Timer 28 and counter 2
7 is unnecessary because, as mentioned above, the control station always changes POL issued from another station to RSV and sends it out. On the other hand, such RSV is RSV
It is detected by the detection circuit 20, and the data transmission mode is changed to the normal repeat mode. The control circuit 29 plays the role of this mode change.

According to this embodiment, the hardware of stations other than the control station can be made simpler than the station hardware in the polling system without lowering the transmission efficiency of the conventional polling system.

In the above embodiment, one control station is used as an example, but it goes without saying that the present invention can also be applied to two or more control stations. Further, the POL counter 27, the timer 28, and the control circuit 24 may be integrated and configured by a microcomputer.

According to the present invention, there are advantages of high efficiency due to the polling rotation system and the ability to simplify the hardware of other stations by providing a polling signal monitoring function to a specific station.

[Brief explanation of drawings]

Figure 1 is a diagram showing a configuration example of loop transmission, Figure 2 is a conceptual diagram of priority control for loop transmission, Figure 3 is a diagram showing the data format required for priority control, and Figure 4 is a diagram showing the priority control of the conventional example. Conceptual diagram of control, Figure 5 is a conceptual diagram of priority control in the conventional example, Figure 6 is a time chart of Figure 4, Figure 7 is a time chart of Figure 5, and Figure 8 is a diagram of the embodiment of the present invention. Conceptual diagram of priority control, No. 9
The figures are a time chart of FIG. 8, FIG. 10 is a block diagram of the priority control section of the control station of the present invention, and FIG. 11 is a block diagram of the priority control section of the station of the present invention. ST1...Control station, ST2~
ST4...Other stations.

Claims (1)

[Scope of Claims] 1 Consists of a serial transmission path and a plurality of stations connected to the serial transmission path that control the transmission and reception of data. In a loop data transmission device using a polling rotation method, which changes the acquired signal to an acquired signal, adds data, and sends it out, and after the data transmission is completed, sends a new transmission right acquisition permission signal downstream. , to at least one of the plurality of stations, regardless of whether there is a transmission request or not, the transmission right acquisition permission signal sent by the other station is unconditionally changed into a transmission right acquired signal and transmitted, and after that, A first means for transmitting a new transmission right acquisition permission signal, and if the transmission right acquisition permission signal sent by the own station returns to the own station as it is via the line, the transmission right acquisition permission signal is sent again. A loop type data transmission control device characterized in that a second means is provided. 2. The loop type data transmission control device according to claim 1, wherein the one station has a function of monitoring the number of times the transmission right acquisition permission signal is received and the reception interval.