JPS63231501A - Data reading control system - Google Patents

Abstract

PURPOSE:To read the data without data competition even when a read command is sent to plural low order controllers simultaneously by sending a next read command after the read command is sent from a high order controller and a read response is returned without fail. CONSTITUTION:When desired low order controllers 2-1-2-N are designated from a high order controller 1 and an auto-read command is sent, the low order controllers respond to the auto-read command, check whether or not a moving body exists in the self-communication area, and when it does not exist, the information to show the absence of the moving body and the read response are immediately returned to the high order controller 1. The high order controller 1, after the system time difference necessary to the communication, can send the auto-read command to the same low order controller or other low order controller immediately, and though the moving body does not easily approach, the waste of the waiting time like waiting for a long time is eliminated.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention relates to a system comprising a host controller, a plurality of lower controllers connected to the host controller, and a plurality of mobile objects that can communicate with these position controllers. The present invention relates to a data read control method when reading data.

(B) Conventional technology Conventionally, when a read command is sent from a multi-drop system upper controller to a plurality of lower controllers and data is read from a moving object that approaches or arrives at the lower controller, as shown in FIG. The upper controller sends an auto-read command to the Nth lower controller in advance, and the Nth lower controller waits for a period of time until the mobile object enters its own communication area, and when the mobile object approaches, it eventually starts communication. Once within the possible range, the lower controller sends a read command to the mobile,
The mobile unit receives this read command and returns the read data along with a read response to the Nth lower controller, and the lower controller receives this read response and returns an auto read response to the higher controller. There is.

(C) Problems to be Solved by the Invention In general, it is completely random in terms of time that a mobile object enters the communicable area of each controller. In the conventional technology described above, when a higher-level controller sends a read command to a plurality of lower-level controllers, read responses from the lower-level controllers may occur simultaneously.

In this case, there is a problem in that a data conflict occurs in the communication path between the upper controller and the lower controller.

On the other hand, if a higher-level controller is configured to send read commands to lower-level controllers sequentially and time-sequentially, and after a read response is returned, it sends a read command to another lower-level controller. No data races occur. However, in this case, there is a problem that communication efficiency is poor because read commands cannot be sent to multiple lower controllers at the same time.

In view of the above, the present invention provides a method for preventing data conflicts from occurring on the communication path even when read responses are returned simultaneously from a plurality of lower-level controllers, and allowing read commands to be sent almost simultaneously from a higher-level controller as required. It is an object of the present invention to provide a data read control method that can improve communication efficiency.

(d) Means and operation for solving the problem The data read control method of the present invention is such that when a higher-level controller sends an auto-read command to a predetermined lower-level controller,
In response to the auto read command, the lower controller immediately checks whether a mobile object exists within the communicable area, reads the data if a mobile object exists, and returns a read response to the upper controller. However, if the mobile object is not present, a read response is sent back to the upper controller along with information indicating the absence of the mobile object.

In this data read control method, when a higher-level controller specifies a desired lower-level controller and sends an auto-read command, the lower-level controller responds to this auto-read command by indicating that a mobile object is present within its own communication area. If it does not exist, information indicating the absence of a mobile object and a read response are immediately sent back to the upper controller. The upper controller is
After the system time difference required for this communication, it is possible to immediately send an auto-read command to the same lower-level controller or other lower-level controllers, eliminating the waste of waiting time that occurs when a moving object does not approach easily. let

Furthermore, if a mobile object exists within the communication area of the lower controller, the lower controller reads data from the mobile object and sends a read response back to the upper controller.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a block diagram showing the configuration of an ID (identification) system in which the present invention is implemented.
N is connected, and furthermore, lower controller 2-+
-2-z, ..., 2-N are connected to read/write heads 3-+13-z, ..., 3-, respectively, and these read/write heads 3--, 34, ...・・・
, 3-N, data carriers (mobile bodies) 4-1.44, . . . , 4. -N approaches/arrives within the communication area from outside the communication area and leaves the communication area.

As shown in FIG. 3, each lower controller 2 includes an upper transmitter 21 and a C
It is composed of a PU 22 and a modulation/demodulation circuit 23 for communicating with the lower side, and the read/write head 3 is composed of a transmitting/receiving circuit.

The data carrier 4 includes a modulation/demodulation circuit 41, an encoding/decoding circuit 42, a command memory controller 43, and an EE
- The device consists of a PROM 44 and a chip IC. This data carrier 4 does not have a built-in power supply,
Power is supplied from the electromagnetically coupled read/write head 3, and data is similarly configured to be exchanged electromagnetically. This data carrier 4 is attached to, for example, an article, a tool, or the like to be transferred on a conveyor and moves. Therefore, when the data carrier 4 enters the communication area of the lower controller 2, power is supplied to the data carrier 4 from the read/write head 3, and conversely, an initial signal is emitted from the data carrier 4, and the lower controller 2 Upon receiving the signal, it is possible to detect that the data carrier 4 has entered the communication area.

Next, the data read operation of the embodiment (1)D system will be explained with reference to the flowchart shown in FIG.

For example, the auto read command from the host controller is N.
When input to the th lower controller [step ST
(hereinafter referred to as ST) 1], the lower controller immediately checks whether the data carrier exists within the communication area, but if the data carrier has not yet arrived within the communication area or does not exist, this determination is made. When the result is NO, the Nth lower controller immediately attaches information indicating the absence of the data carrier to the auto read response and sends it back to the upper controller side (Sr2). After a time lag between sending this auto read command and receiving an auto read response, the upper controller sends the next auto read command again to the same lower controller, for example (5T3), and similarly, if the data carrier is within the communication area. Check whether it is there. For example, if the data carrier does not exist within the communication area, an auto-read response indicating the absence of the data carrier is immediately returned to the higher-level controller.

Then, the higher-level controller sends an auto-read command to the lower-level controller (5T5), and as a result of checking the existence of the data carrier in the lower-level controller,
Here, for example, if the data carrier has already arrived within the communication area, this determination will be YES, and therefore the lower controller will send a read command to the data carrier (5T6), and the data carrier receiving this will Then, data at the desired address is read and a read response is returned to the lower controller (Sr7). The lower controller returns the read response with this data to the upper controller as an auto read response (Sr1).

The higher-level controller sends an auto-read command to each lower-level controller, and if the read response in that lower-level controller is a return indicating that the data carrier is absent, it repeatedly sends the auto-read command to the same lower-level controller 2 for a predetermined period of time. When the time has elapsed, an auto-read command may be obtained for the next lower-level controller, or an auto-read command may be sent to each lower-level controller once, and an auto-read response may indicate that the data carrier is absent. Then, the lower controller that sends the auto read command next may be sent sequentially.

The operation shown in Figure 1 above is to send a so-called auto-read command to the lower controller, and if the data carrier does not exist, an auto-read response indicating the absence of the data carrier is sent back, and if the data carrier does exist, the auto-read command is sent to the lower controller. The so-called polling method is used to read data by sending a read command to the auto-read command, but the wait method is also possible as before, and the switch between the wait method and polling method can be specified in the auto-read command. Either the conventional wait method or the polling method according to the present invention may be selected by transmitting this specified command from the host controller.

Figure 4 shows the format of the auto read command used in such cases. Here, in addition to the N00 (number) of the lower controller and the type of command, the format for the wait and polling (W/P) is shown. It has 1 bit of data indicating.

The wait and polling method switching shown in Figure 4 is as follows:
Although an example in which the method is specified by the upper controller is shown, it is also possible to specify the method by the lower controller.

FIG. 5 shows the general configuration of the keyboard 51.
(or a switch), the designation of the wait method or the polling method is registered and stored in the memory 52 in advance, and when an auto read command is input to that controller from the upper controller, it is determined whether it is the polling method or the wait method (5T51). Referring to the setting contents of the memory 52, if the polling method is used, execute reading using the polling method (5T52), and if the wait method is used, execute processing using the wait method (ST52).
53), the auto-read response will be sent back to the higher-level controller. The specific flow is shown in FIG.

When an auto-read command is input from the upper controller to the Nth lower controller (ST1), the lower controller determines whether or not it is polling (ST2), and if polling is specified, this determination becomes YES and the data carrier communicates. Determine whether it is within the area. If it is outside the area, an auto-read response is sent back to the upper controller along with information indicating the absence of the data carrier using the polling method (ST3).The upper controller sends an auto-read command to the lower controller again (ST4). If the data carrier is still outside the area, the lower controller returns an auto-read response to the upper controller together with information indicating the absence of the data carrier (ST5).

Next, if the predetermined time has still elapsed, the higher-level controller sends the auto-read command again to the Nth lower-level controller (5T6). If the data carrier exists within the area at this point, the lower-level controller sends the read command. is transmitted to the data carrier (ST7). The data carrier receives this read command, reads the data at the specified address, and sends it back to the lower controller as a read response (ST8). The lower controller sends this read response back to the upper controller as an auto read response (ST9). When the higher-level controller receives this return, it proceeds to the auto-read command for the next, ie, the N+1st lower-level controller.

On the other hand, in the case of wait in ST2, as in the past, a time wait is performed until the data carrier arrives and enters the communication area, and once the data carrier enters the communication area, a read command is sent to the data carrier for the first time. Send (ST
7). Therefore, in this case, the auto read commands in ST4 and ST6 will not be transmitted.

FIG. 7 shows a flow diagram of another embodiment ID system. In this case, the upper controller sends an auto-read command to a plurality of lower controllers N and N+1, respectively, and checks whether data carriers n and n+1 have arrived at lower controller N and lower controller N+1, respectively. First, when an auto-read command is sent from the upper controller to the lower controller N, if the data carrier n is outside the area, it will send a message to that effect. The indicated auto read response is sent back to the upper controller. In response to this, an auto-read command is sent to the lower controller N+1, and the lower controller N+1 determines whether or not the data carrier n+l is within the area, and if it is outside the area, it is sent along with data indicating that. Sends the auto read response back to the upper controller.

Next, the upper controller sends an auto read command to the lower controller N, and the lower controller N
In response to this auto read command, data carrier n
is within the area, a read command is sent to the data carrier n, and the data carrier n reads the data,
Send it to the lower controller N as a read response,
The lower controller N sends an auto-read response to the upper controller. Similarly, the upper controller sends an auto-read command to the lower controller N+1, and at this point, if the data carrier n+1 is within the communication range of the lower controller N+1, the lower controller N+
1 sends a read command to data carrier n+1,
The data carrier reads data and transmits a read response to the lower controller N+1.

(f) Effects of the Invention According to this invention, after a read command is sent from a host controller, the next read command is sent after a read response is always returned, so if the system response time is ignored, the apparent Even if read commands are sent to multiple lower controllers at the same time, data can be read without causing data conflicts.

The upper controller sequentially sends a read command to the lower controller, and after receiving the read response,
Even in a system that sends a read command to another lower-level controller, when the lower-level controller receives the read command, if the mobile object is within the communicable area of the lower-level controller, it immediately returns a read response. Therefore, after receiving the read response, the higher-level controller can apparently send a read command to other lower-level controllers without waiting time, which has the advantage of greatly improving communication efficiency.

[Brief explanation of drawings]

FIG. 1 is a flow diagram for explaining the data read operation of an ID system according to an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of an ID system according to an embodiment of the invention, and FIG.
FIG. 4 is a block diagram showing the configuration of the lower controller and data carrier of the D system. FIG. 4 is a diagram showing an example of the configuration of the auto read command. FIG. 5 is a block diagram showing the configuration of the lower controller and the data carrier. 6 is a flowchart showing the operation of another embodiment, FIG. 7 is a flowchart showing the operation of still another embodiment, and FIG. 8 is a flowchart for explaining the conventional data read operation. It is a diagram. 1: Upper controller, 2-1, 2-2...2-s: Lower controller, 3-t, 3-2...3-N: Read/write head, 4-1・4-2...4-N: Data carrier. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigeru Nakamura Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] (1) Data is read from the mobile object using an auto read command from the upper controller between a host controller, a plurality of lower controllers connected to the host controller, and a plurality of mobile objects that can communicate with these lower controllers. In the data read control method, when the higher-level controller sends an auto-read command to a predetermined lower-level controller, the lower-level controller immediately determines whether or not the mobile object is within a communicable area in response to the auto-read command. If a mobile object is present, data is read and a read response is sent back to the upper controller; if no mobile object is present, a read response is sent back to the upper controller along with information indicating the absence of a mobile object. A data read control method characterized by the following.