JPS59181747A - Data transmission controlling system - Google Patents

Abstract

PURPOSE:To obtain a utilization factor of a transmission line which is equal to dynamic assignment without changing a transmission control procedure, etc., and to shorten remarkably an ineffective time by adding a simple constitution for providing a signal detecting means and a timer part on a master station. CONSTITUTION:A control part 70 sends out contents of an address counter 54 to a transmission line 40 from a driver 50 through a transmitting circuit 52 in order to send out a mark to each station. As a result, the mark to the slave station corresponding to the address counter 54 is sent out from the transmitting circuit 52. The corresponding slave station which has received the mark sends out a transmitting data in case when the transmitting data exists, and executes no response in case when said data does not exists. A timer 56 is started from when the mark is sent out. After the mark is sent out, a signal detecting part 62 monitors through a receiver 60 whether the data is sent out to the transmission line 40 from the slave station or not. When a signal detecting part 62 detects a fact that the data is sent out onto the transmission line, a detecting signal 72 is sent to a transmission discriminating part 64, and also the data on the transmission line is stored in a receiving buffer 68 through a receiving circuit 66.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a data transmission control system in a parent-child communication type transmission system that performs time division multiplex communication on a bus-like transmission line.

Prior Art Conventionally, in a parent-child communication type transmission system that performs time-division multiplex communication, a master station accesses a connected slave station by outputting a time-division control signal at a timing unique to the connected slave station. was giving authority. For this reason, regardless of the access frequency of each slave station, a fixed time division is applied at fixed time intervals, and there is a large amount of invalid time except when the access frequency is extremely high. An example of this is shown in FIG. 1(a).

Furthermore, as a method for eliminating the above-mentioned drawbacks, various methods have been proposed in which the access timing of each terminal is dynamically allocated in a fixed manner. However, in order to perform dynamic interrogation, a response function to the command was added and a complicated control procedure was executed, making the control and configuration extremely complex and expensive.

Purpose The present invention has been made to overcome the above-mentioned drawbacks, and achieves the same performance as dynamic allocation without using a distinct control procedure.
Another object of the present invention is to propose a data transmission control system realized with a simple configuration.Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1(a) is a conventional transmission timing chart,
Figure (b) is a transmission timing chart of this embodiment, and Figure 2 is a detailed diagram of the transmission timing chart of this embodiment by the sound μ.
FIG. 3 is an example diagram of a transmission system. As shown in the figure, conventionally, a time-division control signal (hereinafter referred to as mark) is sequentially outputted from a master station 20 to each slave station. First, mark 1 for slave station A22 is output, transmission data 2 is output from slave station A22 in response to mark 1, then mark 3 is output for slave station B24, and similarly transmission data 4 from slave station B24 is output. Output. Next, mark 5 is output to slave station C26, but slave station C26 does not transmit anything because it has no data to transmit. Similarly, mark 6 is output to the slave station D28, but nothing is transmitted from the slave station D28. Subsequently, mark 7 for slave station E30 is output, and slave station E30 sends data 8 in response.

In this transmission control, allocation to the slave station C26 and slave station D28 results in idle time on the transmission bus 40 for a minute.

Therefore, by providing the time division control section 21 shown in FIG. 4 in the master station 20, the above-mentioned idle time can be significantly reduced. In FIG. 4, the control unit 70 sends the contents of the address counter 54 to the driver 50 via the transmission circuit 52 in order to send a mark to each slave station.
0 is sent to the transmission line 40. As a result, a mark is sent to the slave station corresponding to the address counter 54.
Send from

The corresponding slave station that received the mark will send out the transmission data if there is transmission data, and will not respond if there is no transmission data.

The timer 56 starts when the mark is sent out.

After transmitting the mark, the signal detection unit 62 monitors whether or not the slave station has transmitted data to the transmission path 40 via the receiver 60. Then, when the signal detection unit 62 detects data transmission on the transmission path, it detects The signal 72 is sent to the transmission determining section 64, and the data on the transmission path is stored in the receiving buffer 68 via the receiving circuit 66.
resets the timer 56.

If there is no data sent from the slave station and there is no response, the signal detection section 62 will not detect a signal, and the data reception signal 74 from the transmission determination section 64 will not be detected even after the time set in the timer 56 has elapsed.
is not output. When the timer output signal 76 from the timer 56 expires, the control section 70 counts up the address counter and sends a mark to the next slave station.

Here, the data transmitted from the slave station has a fixed length.

When the transmitting circuit 52 receives a command to send out a signal from the control unit 7o, it sends out a preamble 80 as shown in FIG. 2, and then outputs a control code 82, slave station address information 84 indicated by the address counter 54, and a check code 86. do.

Then, the transmission delay time t1 depends on the line length, the access time t40 'c, the response time t2 from the slave station, and the transmission delay time t3 depending on the line length from the slave station, etc. Time elapsed (
After one hour has elapsed, the timer 56 is activated and a preamble 88 for the next mark is sent out.

Effects As explained above, according to the present invention, transmission equivalent to dynamic allocation can be achieved without changing the transmission control procedure etc. by adding a simple and inexpensive configuration in which the master station is equipped with a signal detection means and a timer section. The road utilization rate was improved, and the idle time was significantly reduced.

[Brief Description of the Drawings] Fig. 1(a) is a conventional transmission timing chart, Fig. 1(b) is a transmission timing chart according to an embodiment of the present invention, and Fig. 2 is a transmission timing chart of the present embodiment when there is no response. FIG. 3 is a detailed diagram of a transmission timing chart, FIG. 3 is an example diagram of a transmission system, and FIG. 4 is a block diagram of a time division control section of a master station. In the figure, 20... Master station, 21... Time division control unit, 22-30... Slave station, 52... Transmission circuit, 54...
...Address counter, 56...Timer, 62...
Signal detecting section, 64... Transmission determining section, 66... Receiving circuit, 68... Receiving buffer, 70... Control section. −2

Claims (1)

[Scope of Claims] 1. In a transmission system in which one master station and at least one slave station are connected via a bus-like transmission path and data is transferred, the master station transmits transmission request information to the slave station in a time-sharing manner. comprising a transmission request sending means for sending out on a transmission path, a detection means for detecting information sending from a slave station to the transmission request sending means, and a detection means for detecting the elapse of a predetermined time from the time when the transmission request was sent, The data transmission is characterized in that, if the detection means does not detect the transmission of information by the time the detection means detects the transmission request after the transmission request transmission means operates, the transmission request information is transmitted to the thorny slave station. control method. 2. The data transmission control method according to claim 1, wherein the detection means operates after a time period obtained by adding the transmission line transmission time to the necessary information transmission time of the id slave station.