JPH0156583B2 - - Google Patents

Description

Detailed Description of the Invention The present invention connects a plurality of slave stations in parallel to a master station via a common transmission line, and a slave station whose address is specified by a call signal from the master station responds. Regarding the signal transmission method, in particular, the storage of the own address in each slave station is checked in a timely manner by a command from the master station.

In general, in this type of signal transmission system, many slave stations are connected in parallel to a common transmission line, so a short-circuit or disconnection accident between the transmission lines that occurs in any slave station can affect the functionality of the entire transmission system. Therefore, various transmission systems have been developed in which measures against such short-circuit and disconnection accidents have been carefully considered.

However, another important problem with this type of transmission system is that in order for the master station to call only a specific slave station, each slave station is assigned a predetermined address code for identification. In the vendor system, 256 stations can be identified using an 8-bit address code using an external digital switch. This address code is an extremely important code for identifying each guest room in each slave station, such as a hotel vendor system. If the address code changes, there will be multiple slave stations with the same address code for the master station, resulting in a serious problem in that the required information will not be reliably transmitted to the required slave stations during communication. This causes serious problems similar to the short-circuit and disconnection accidents mentioned above.

In other words, in this type of conventional signal transmission system, once an abnormality occurs in the address code of a slave station, it cannot be easily recovered from, and in reality, some slave stations have a problem with their own address code. There was a forgetfulness. In other words, in the conventional signal transmission system of this type, consideration is given to ensure that each slave station retains its own address code, but once an error occurs in the memory of the address code, there is no way to recover it. Because it does not have a memory address code, it is difficult to recover the stored address code.

SUMMARY OF THE INVENTION An object of the present invention is to provide a signal transmission system that eliminates the above-mentioned conventional drawbacks, has high reliability for the identification address code of each slave station, and is easy to maintain.

That is, the signal transmission system of the present invention connects multiple slave stations in parallel to a master station via a common transmission line, and transmits a signal in which a slave station to which its address is specified by a call signal from the master station responds. In the transmission method, when the calling signal from the master station is provided with a calling signal for all slave stations, and each slave station checks the calling signals from all slave stations,
This device is characterized in that the address of its own station, which is set in advance for each station, is written anew into each communication memory.

The present invention will be described in detail below with reference to the drawings.

First, FIG. 1 shows the format of a communication signal used in conventional signal transmission of this type of system. In the illustrated format, following the start bit signal St indicating the start of communication, the control bit signal S/
CD, a check-in bit signal Ci, and a check-out bit signal Co are provided, and then an 8-bit code signal consisting of ²⁷ to ²⁰ is arranged as an address code, and then "1" representing the required communication information is arranged. ”, “0” code signals were sent from the master station to the slave stations. Each slave station connected in parallel with a common transmission line receives a communication signal with such a configuration, and if the communication signal specifies its own station according to its address code, it sends a reply signal to the master station. After transmitting the data back to the master station, it performs internal processing according to the communication information in the communication signal, and sends the processing results and the current status of its own station as reply information to the master station.

On the other hand, in the format of the communication signal according to the method of the present invention, as shown in FIG.
Signal to call all slave stations following the conventional configuration shown
A slave station with Sal added and specified by the address code checks its own address code according to the signal Sal, and at the same time all other slave stations simultaneously check their own address code. The codes are rewritten in the communication memory based on code signals set in advance. At this time, the other slave stations only rewrite their own address code and do not send any reply signals to the master station.

Next, FIG. 3 shows a flowchart of signal processing in a conventional slave station that receives a communication signal according to the conventional configuration shown in FIG. That is, step
The reception process is performed in S1, and then it is determined in step S2 whether or not the reception was successful. If it is determined that the reception was successful, the address code in the communication signal specifies the own station in step S3. If it is determined that the local station is called, internal processing is performed in accordance with the communication information in the communication signal at step S4. However, step S2
If it is determined in step S3 that the reception has not been successful, and if it is determined in step S3 that the local station is not called, the slave station does not take any action. Therefore, in the signal processing according to the flowchart shown in Figure 3 according to the conventional method corresponding to the communication signal with the configuration shown in Figure 1, a single child is processed for one communication signal transmission from the master station. Although only a call can be made to the station, during normal communication without any interference, communication using this conventional method was sufficient.

On the other hand, FIG. 4 shows a flowchart of signal processing in a slave station according to the present invention which receives a communication signal with the configuration shown in FIG. In the flowchart shown in FIG. 4, steps S5 and S6 are added to the conventional flowchart shown in FIG. According to the configuration, confirmation by rewriting the memory of the own station address code according to the all slave station calling signal Sal in the communication signal is given priority to signal processing based on address code identification, and the address code different from the own station address code is triggered. When the subsequent all slave station calling signal Sal is received,
When the own station address code is rewritten to the communication memory in step S6, and when the all slave station calling signal Sal follows the own station address code, the own station address code is identified in step S3 as before. Following the step
Necessary signal processing is performed in S4.

Therefore, according to the signal processing shown in FIG. 4 in the slave station according to the present invention which has received the communication signal with the configuration shown in FIG. Even if there is a shift, the normal memory state is automatically restored after a predetermined period of time has elapsed, so there is no problem with the signal transmission system, and even when another slave station calls, the local station of each slave station is Address code memory is reconfirmed.

However, in the signal processing according to the flowchart shown in FIG. 4, during the process of rewriting the address code of the own station into the memory device, the confirmation of the call to the own station by identifying the address code in the communication signal is still performed in step S3. Therefore, as shown in Fig. 5, all slave station calls are sent every time each slave station A and B calls. If all the slave stations simultaneously reconfirm their address code memory in response to the signal Sal, the period during which communication is unavailable will increase because the reconfirmation process is in progress. As shown, each slave station A,
In response to calls from B and C, each called slave station A,
Each of B and C immediately responds to a call from the master station without reconfirming the memory of its own address code, and this reconfirmation process is carried out when the power is turned on at each slave station and when the own station You can also change the flowchart to only run when you are sure that you are not being called.

In addition, in order to have each slave station confirm by rewriting its address code memory according to a command from the master station, a special all-station calling signal Sal is inserted into the communication signal as shown in Figure 2. In addition, a bit configuration is used in which the check-in bit signal Ci and the check-out bit signal Co in the format shown in FIG. 1 may become "0" at the same time, but never become "1" at the same time. By simultaneously setting the check-in bit signal Ci and the check-out bit signal Co to "1", each slave station can be made to reconfirm its own address code storage.

As is clear from the above explanation, according to the present invention, whereas address codes are conventionally used to perform one-to-one communication between a master station and a slave station, Since the communication signal is configured to add bit information that calls all slave stations with priority, it is possible to prevent confusion in communications throughout the transmission system due to forgetting of its own address code in any slave station, and By providing a recovery means against an accident, the reliability of the entire transmission system can be ensured, and the special effect of being able to send commands to all slave stations at the same time can be obtained.

Note that the signal transmission system of the present invention can be applied not only to the hotel vendor system described above, but also to general signal transmission systems that share a transmission line.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the structure of a communication signal according to the conventional signal transmission method, Fig. 2 is a diagram showing an example of the structure of a communication signal according to the signal transmission method of the present invention, and Fig. 3 is a diagram showing the structure of a communication signal according to the conventional signal transmission method. FIG. 4 is a flowchart showing an example of the received signal processing process in the signal transmission system of the present invention, FIG. 5 is a diagram showing an example of the communication mode, and FIG. 6 is the same. FIG. 7 is a diagram showing another example of the mode of communication.

Claims (1)

[Claims] 1 In a signal transmission system in which multiple slave stations are connected in parallel to a master station via a common transmission line, and the slave station responds to its own address by a paging signal from the master station, A calling signal for all slave stations is provided as a calling signal, and when each slave station confirms the calling signal for all slave stations, it rewrites the address of its own station, which has been set in advance, into its communication memory. A signal transmission method characterized by: