JP2910271B2 - Communication control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control system in a system in which a control station and a plurality of subordinate stations are connected by a common signal line. The present invention relates to a communication control method that can be searched for in a short time.

[0002]

2. Description of the Related Art In a system in which a control station 41 and a plurality of subordinate stations 42-1 to 42-N are connected by one transmission line 43 and one reception line 44 as shown in FIG. Bureaus 42-1
Conventionally, when an interrupt factor occurs in the slave station 42-N, the slave stations 42-1 to 42-N transmit a break signal to the control station 41 via the reception line 44 and receive the break signal if the interrupt is enabled. The control station 41 temporarily suspends the interruption by the break signal from the dependent stations 42-1 to 42-N, and then sends a command to make each dependent station report its state according to a predetermined priority. Until a report indicating that the request has been received is issued.

[0003]

As described above, conventionally, when a break signal is applied from a subordinate station, the control station issues commands to report the status to each subordinate station in order according to priority. The slave station where the interrupt factor that caused the break signal was sent was found, so if a break signal was sent from a slave station with a lower priority, useless operations had to be repeated until this slave station was found. However, there was a problem that the efficiency of interrupt processing was reduced.

An object of the present invention is to improve the efficiency of interrupt processing by enabling a subordinate station that has transmitted a break signal to be searched in a short time.

[0005]

In order to achieve the above object, the present invention provides: (A) a plurality of subordinate stations connected to a control station via a common signal line, and each of the subordinate stations is controlled by a break signal; In a communication control method for notifying a station of an interrupt, a break signal length table storing a signal length of a break signal assigned to each of the dependent stations is added to the control station via the signal line. A break signal length measuring unit for measuring the signal length of a break signal, and a dependent station to which a break signal equal to or less than the signal length measured by the break signal length measuring unit is assigned with reference to the break signal length table. The control station sequentially outputs an instruction for inquiring each dependent station whether a break signal has been transmitted or not until a response indicating that a break signal has been transmitted is received. A control unit, wherein each of the slave stations stores a break signal length storage unit in which a signal length of a break signal assigned to its own slave station is stored; and A break signal having a stored signal length is transmitted to the signal line, and a response indicating whether or not the slave station has transmitted a break signal is transmitted to the signal line by receiving the command from the control station. And a dependent station control unit.

The present invention also provides a method for searching for a subordinate station that has transmitted a break signal in a shorter time. (B) A plurality of subordinate stations are connected to a control station via a common signal line. In the communication control system in which each dependent station notifies an interrupt to the control station by a break signal, the control station has a break signal length table storing a signal length of a break signal assigned to each dependent station. A break signal length measuring unit for measuring a signal length of a break signal applied via the signal line; and a break having the same signal length as the signal length measured by the break signal length measuring unit with reference to the break signal length table. A command to search for the subordinate station to which the signal is assigned and to inquire whether each of the searched subordinate stations has transmitted a break signal or not is transmitted. Until receiving a response indicating, and a control station control unit that sequentially outputs, provided in each of the dependent stations, a break signal length storage unit in which the signal length of the break signal assigned to its own dependent station is stored, It is determined whether or not a break signal has been transmitted to the signal line by the occurrence of an interrupt factor, and the break signal having the signal length stored in the break signal length storage unit is determined by determining that the break signal has not been transmitted. A slave station control unit that sends a signal indicating whether or not the slave station sends a break signal to the signal line by sending the signal to the signal line and receiving the command from the control station. It is.

Further, according to the present invention, when a break signal is simultaneously output from slave stations having different priorities, interrupt processing for a slave station having a higher priority can be executed first. A station and a plurality of subordinate stations are connected via a common signal line, and in the communication control system in which each subordinate station notifies the control station of an interrupt by a break signal, the control station and the subordinate stations are connected to each other. A break signal length table in which the signal length of the assigned break signal is stored, a first break signal length measuring unit for measuring the signal length of the break signal applied through the signal line, and the break signal length table To find a subordinate station to which a break signal having the same signal length as the signal length measured by the first break signal length measuring unit is assigned, and to each of the found subordinate stations. A control station control unit for sequentially outputting an instruction for inquiring whether or not a break signal has been transmitted to the dependent station until a response indicating that the break signal has been transmitted is provided; A break signal length storage unit in which the signal length of the break signal assigned to the slave station is stored; a second break signal length measuring unit for measuring the signal length of the break signal transmitted to the signal line; It is determined whether or not a break signal has been transmitted to the signal line due to the occurrence of a factor.If it is determined that the break signal has not been transmitted, the break signal having the signal length stored in the break signal length storage unit is determined. The signal is sent to the signal line, and when it is determined that the signal is sent, the signal length measured by the second break signal length measuring unit is longer than the signal length stored in the break signal length storage unit. A break signal whose signal length is the difference between the signal length stored in the break signal length storage unit and the signal length measured by the second break signal length measurement unit is transmitted to the signal line. And a dependent station control unit for transmitting a response indicating whether or not the own dependent station has transmitted a break signal to the signal line by receiving the command from the control station.

[0008]

In the configuration of (A), each slave station uses the slave station control section to send a break signal of the signal length stored in the break signal length storage section when an interrupt factor occurs in its own slave station. The signal is transmitted to the signal line to which the control station and each subordinate station are connected. The control station measures the signal length of the break signal using the break signal length measurement unit when a break signal indicating that an interrupt factor has occurred is added via a signal line, and further, the control station control unit controls the break signal length. With reference to the table, a subordinate station to which a break signal shorter than the signal length of the break signal measured by the break signal length measuring unit is assigned is searched. This is because only the slave stations to which the same break signal length as the measured break signal length is assigned output the break signal, or a plurality of slave stations to which a break signal length shorter than the measured break signal length is assigned. This is because it is considered that the dependent stations output the break signal at the same time. Next, the control station issues an instruction to inquire whether each of the searched control stations has transmitted a break signal until a response indicating that the break signal has been transmitted is received.
Send out sequentially. The dependent station that has received the command from the control station sends a response to the signal line indicating whether or not its own dependent station has transmitted a break signal, using the dependent station control unit.

[0009] In the configuration of (B), when the subordinate station generates an interrupt factor in its own subordinate station, the subordinate station determines whether or not a break signal is transmitted to the signal line by using the subordinate station control unit. By determining that the break signal has not been transmitted, the break signal having the signal length stored in the break signal length storage unit is transmitted to the signal line. Therefore, a plurality of subordinate stations do not output a break signal at the same time. When a break signal is applied via the signal line, the control station measures the signal length of the break signal using the break signal length measurement unit, and further refers to the break signal length table by the control station control unit to measure the break signal length. A command indicating that a subordinate station to which the same signal length as the measured signal length has been assigned is searched, and an inquiry as to whether or not a break signal has been transmitted to each subordinate station that has been searched is sent. Until they are received. The dependent station that has received the command from the control station sends a response to the signal line indicating whether or not its own dependent station has transmitted a break signal, using the dependent station control unit.

[0010] In the configuration (C), when the subordinate station generates an interrupt factor in its own subordinate station, the subordinate station uses the subordinate station control unit to determine whether or not a break signal is transmitted to the signal line. If it is determined that the break signal has not been transmitted, a break signal having the signal length stored in the break signal length storage unit is transmitted to the signal line. If it is determined that the signal has been transmitted, the signal length is determined to be smaller than the signal length stored in the break signal length storage unit, provided that the measurement result of the second break signal length measurement unit is shorter than the signal length. A break signal which is a difference between the signal length stored in the storage unit and the signal length measured by the second break signal length measuring unit is transmitted to the signal line as soon as possible after the transmission of the break signal for the measurement is stopped. That is, when an interrupt cause is generated in a plurality of slave stations at the same time, a break signal having the longest signal length among the break signals assigned to each slave station in which the interrupt cause has occurred is added to the control station. become. When the break signal is applied via the signal line, the control station measures the signal length of the break signal using the first break signal length measurement unit, and further refers to the break signal length table by the control station control unit, An instruction for searching for a subordinate station to which the same signal length as the signal length measured by the first break signal length measuring unit is assigned, and inquiring each of the subordinate stations searched for whether a break signal has been transmitted or not, is issued as a break signal. Are sequentially transmitted until a response is received indicating that has been transmitted. The dependent station that has received the command from the control station sends a response to the signal line indicating whether or not its own dependent station has transmitted a break signal, using the dependent station control unit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, in which a control station 1 and a plurality of subordinate stations 2-1 to 2-N are connected (wired) by one transmission line 3 and one reception line 4. Or)

The control station 1 includes a control station control unit 11, a transmission / reception unit 13, a break signal length table 14, a break signal length measurement unit 15, and a break signal length monitoring timer 16. The control station control section 11 includes priority order determining means 12 for performing the processing shown in the flowchart of FIG. The transmitting and receiving unit 13 transmits and receives signals to and from the dependent stations 2-1 to 2-N. The break signal length table 14 stores the signal lengths of the break signals transmitted from the dependent stations 2-1 to 2-N to the reception line 4. The break signal length measuring unit 15 measures the signal length of the break signal applied via the reception line 4. The break signal length monitoring timer 16 times out when a time corresponding to the maximum break signal length elapses after the measurement of the signal length of the break signal is started.

The slave station 2-j (1 ≦ j ≦ N) includes a slave station control unit 21, a break signal length storage unit 23, and a transmission / reception unit 24.
It is composed of The slave station control unit 21 includes a break signal length control unit 22 for controlling the signal length of the break signal transmitted to the reception line 4. Break signal length storage unit 2
3 stores the signal length of the break signal assigned to the subordinate station 2-j. The transmission / reception unit 24 transmits / receives a signal to / from the control station 1. The other dependent stations have the same configuration as the dependent station 2-j. In addition, each dependent station 2-
The signal lengths of the break signals assigned to 1 to 2-N may be any signal lengths, as long as they are not all the same signal length.

Next, the operation of this embodiment will be described with reference to the drawings. The subordinate station control unit 21 of the subordinate station 2-j transmits the subordinate station 2-j.
When an interrupt factor occurs in j, a break signal having the signal length stored in the break signal length storage unit 23 is sent to the receiving line 4 using the break signal length control means 22. The writing of the signal length to the break signal length storage unit 23 can be performed by giving a break signal length write command instructing the writing of the break signal length from the control station 1 to the dependent station 2-j. Also, when an interrupt factor occurs in the slave station, the slave station sends a break signal having the signal length assigned to the slave station to the reception line 4 as in the slave station 2-j.

When the transmitting / receiving section 13 in the control station 1 detects a low level of one or more characters, it notifies the control station control section 11 of the start of break detection. Upon receiving this notification, the control station control unit 11 instructs the break signal length measuring unit 15 to start measuring the break signal length, and starts the break signal length monitoring timer 16. The break signal length monitoring timer 16 times out when a time corresponding to the maximum signal length out of the signal lengths of the break signals assigned to the subordinate stations 2-1 to 2-N elapses.

When the control station control unit 11 is notified of the start of the break detection from the transmission / reception unit 13 and then receives a break signal reception end notification from the transmission / reception unit 13 or a timeout notification from the break signal length monitoring timer 16. , And instructs each of the subordinate stations 2-1 to 2-N to prohibit interruption (prohibition of transmission of a break signal) via the transmission line 3, and thereafter,
The process shown in FIG. 2 is performed using the priority order determining means 12. Here, when a time-out notification is added from the break signal length monitoring timer 16, the process shifts to the process of instructing each of the subordinate stations 2-1 to 2-N to disable the interrupt. 2-N are wired-OR connected to the receiving line 4, and when a plurality of subordinate stations transmit break signals at the same time, a low-level period is included in the signal length of the break signal assigned to each subordinate station. This is because the signal length may be longer than the longest signal length. In other words, if the break signal length monitoring timer 16 is not provided, it is not possible to shift to the next process even after the time corresponding to the maximum break signal length has elapsed, resulting in waste of time. If the measured value exceeds the maximum break signal length, the break signal length measuring unit 15 may have a function of notifying the control station control unit 12 of a timeout without providing the break signal length monitoring timer 16. Can also.

As shown in FIG. 2, the priority order determining means 12 first reads the signal length L of the break signal measured by the break signal length measuring unit 15 (S1), and then refers to the break signal length table 14. A set of dependent stations G (L) to which a break signal having a signal length of L or less is assigned is searched for, and is set as a set G of dependent stations that issue a status notification instruction (S2). Thereafter, the priority determination means 12 determines whether or not the set G is an empty set (S3). If it is determined that the set is an empty set, the process is terminated. If not, the process of S4 is performed. .

At S4, a command for status notification is issued to the subordinate station 2-K having the longest signal length of the assigned break signal among the subordinate stations included in the set G. Delete 2-K.

When the slave station 2-K receives the status notification command from the control station 1, it returns a response including information indicating whether or not a break signal has been sent to the control station 1.

When a response is received from the dependent station 2-K (S
6, S7), and the priority determination means 12 analyzes it (S7).
8) If it is determined that the dependent station 2-K is the dependent station that has transmitted the break signal (if S9 is YES), the interrupt factor is processed (S10), and the system is returned to the interrupt enabled state again. Let it. In S9, the dependent station 2
If it is determined that −K is not the dependent station that transmitted the break signal, the process returns to S3, and the same operation is repeated for the set G. Here, the reason that the priority order for issuing the status notification instruction is set higher for the slave station having a longer signal length is that there is little possibility that a plurality of slave stations output a break signal at the same time, and the longest signal length is assigned. This is because there is a high possibility that the dependent station has transmitted the break signal. Further, the slave station that has sent the break signal has passed a certain time (for example, the time required for the priority order determining means 12 to issue a status notification command to all the slave stations) after sending the break signal. Even if the control station 1 does not receive a state notification command, the control station 1 sends a break signal again.

In the above-described embodiment, each of the subordinate stations 2-1 to 2-N immediately sends a break signal to the receiving line 4 when an interrupt cause occurs. At this time, the state of the receiving line 4 is checked and a break signal is sent immediately if the signal is at a high level, and the break signal is canceled if the signal is at a low level. The subordinate station that has transmitted the signal can be found, and the break signal length monitoring timer 16 can be eliminated. However, in this case, S2 of the priority order determination means 12
Is referred to as a set G of subordinate stations to which a break signal whose signal length is equal to or less than the measured value L of the break signal length measuring unit 15 is assigned with reference to the break signal length table 14.
(L) is searched, and these are set as a set G of the dependent stations that issue the status notification instruction. ”The break whose signal length is equal to the measured value L of the break signal length measuring unit 15 with reference to the break signal length table 14 It is desirable to search for the set G (L) of the dependent stations to which the signal is assigned and change them to the set G of the dependent stations that issue the status notification command. "

As described above, when another subordinate station is transmitting a break signal, the break signal is not transmitted even if an interrupt factor occurs. Is the signal length of the break signal assigned to the subordinate station that sent the break signal, so that the number of subordinate stations to which the status notification instruction is issued can be reduced. In this case, the subordinate station that has transmitted the break signal can be quickly searched out.

FIG. 3 is a block diagram of another embodiment of the present invention, and shows the configuration of the dependent station 2-j. The subordinate station 2-j in the present embodiment includes a subordinate station control unit 31, a break signal length storage unit 34, a low level length measurement unit 35, and a transmission / reception unit 36. The slave station control unit 31 includes an output low level length determining unit 32 and a break signal length controlling unit 3.
3 and the output low level length determining means 32
The break signal length control means 33 outputs a low-level signal having the signal length determined by the output low-level length determination means 32 to the reception line 4.
The break signal length storage unit 34 stores the signal length of the break signal assigned to the dependent station 2-j. The low-level length measuring unit 35 measures the subsequent low-level length every time the reception line 4 goes low by one or more characters. The transmission / reception unit 36 controls transmission and reception of information with the control station 1.

Next, the operation of this embodiment will be described. The output low level length determining means 32 in the dependent station control unit 31 detects the occurrence of an interrupt factor in the own dependent station 2-j,
Is low, that is, whether another subordinate station is transmitting a break signal to the reception line 4. When it is determined that the state of the reception line 4 is at the high level, that is, when it is determined that no other dependent station has transmitted a break signal, the signal length L0 stored in the break signal length storage unit 34 is determined. Is the signal length L1 of the low-level signal transmitted to the reception line 4. When it is determined that the state of the reception line 4 is at the low level, that is, when it is determined that another dependent station is transmitting a break signal to the reception line 4, the measurement value L2 of the low level length measurement unit 35 is used. Is read and compared with the signal length L0 stored in the break signal length storage unit 34. When L2 ≧ L0, the signal length L1 of the low-level signal transmitted to the reception line 4 is set to “0”, and L2
In the case of <L0, L0-L2 is set as the signal length L1 of the low-level signal to be output to the reception line 4. When the signal length L1 of the low-level signal to be transmitted to the receiving line 4 is determined by the output low-level length determining means 32, the break signal length control unit 33 outputs a low-level signal having the signal length determined by the output low-level length determining means 32. Is output to the receiving line 4.

Therefore, when another slave station does not send a break signal when an interrupt factor occurs in the slave station 2-j, the control station 1 notifies the control station 1 of the signal length assigned to the slave station 2-j. A break signal is added, another slave station sends a break signal, and the signal length is set to the slave station 2-
If the signal length is shorter than the signal length assigned to j, a break signal having the signal length assigned to the dependent station 2-j is added to the control station 1, and the other dependent stations send out a break signal. If the signal length is longer than the signal length assigned to the dependent station 2-j, a break signal having the signal length assigned to the other dependent station is added to the control station 1. That is, when an interrupt cause occurs in a plurality of slave stations at the same time, a break signal having the longest signal length among the break signals assigned to the plurality of slave stations in which the interrupt cause has occurred is added to the control station 1. Therefore, the priority of interrupt processing for each subordinate station can be set by the length of the break signal transmitted from each subordinate station.

The operation of the control station 1 in this embodiment may be the same as that of the embodiment shown in FIG. 1, but the processing of S2 in the priority order determining means 12 is described as "break signal length". With reference to the table 14, a set G (L) of subordinate stations to which a break signal whose signal length is equal to or less than the measured value L of the break signal length measuring unit 15 is searched, and the subordinate station which issues a state notification instruction is determined. , A set G (L) of subordinate stations to which a break signal whose signal length is equal to the measured value L of the break signal length measuring unit 15 is assigned with reference to the break signal length table 14. These are referred to as a set G of subordinate stations that issue status notification instructions. "

[0027]

As described above, according to the first aspect of the present invention, the signal length of the break signal is determined for each slave station, and the control station transmits the break signal based on the signal length of the received break signal. A group of slave stations that may have sent the slave station is determined, and a command to inquire whether a break signal has been output is output only to slave stations in the group. There is an effect that the dependent station can be quickly searched out, and the efficiency of interrupt processing can be improved as compared with the conventional example.

The invention according to claim 2 is characterized in that, when an interrupt factor occurs in each subordinate station, it is determined whether or not another subordinate station is transmitting a break signal, and it is determined that no break signal is being transmitted. Only a break signal having a signal length assigned to the slave station is transmitted, so that a plurality of slave stations do not output a break signal at the same time. Therefore, it is not necessary to consider the overlap of the break signals, so that there is an effect that the efficiency of the interrupt processing can be further improved.

Further, according to the present invention, when an interrupt factor occurs in each subordinate station, it is determined whether or not another subordinate station has transmitted a break signal, and it is determined that no break signal has been transmitted. If so, a break signal having the signal length stored in the break signal length storage unit is transmitted to the signal line, and if it is determined that the signal is transmitted, the signal length of the transmitted break signal is assigned to the slave station. The break signal output is supplemented so that the break signal length on the signal line matches the signal length assigned to the slave station on condition that the break signal length is shorter than the signal length of the slave station. When an interrupt factor occurs, a break signal having the longest signal length among the break signals assigned to the plurality of subordinate stations in which the interrupt factor has occurred is added to the control station. , By previously assumed higher priority break signal length is longer dependent stations, there is an effect that it becomes possible to perform the interrupt processing for the high-priority tributary station first.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a flowchart showing a processing example of a priority order determining means 12;

FIG. 3 is a block diagram of another embodiment of the present invention.

FIG. 4 is a block diagram of a system to which the present invention is applied.

[Explanation of symbols]

 1, 41: Control station 2-1 to 2-N: Dependent station 3: Transmission line 4: Reception line 11: Control station control unit 12: Priority determination means 13, 24, 36 ... Transmission / reception unit 14: Break signal length table 15: Break signal length measuring section 16: Break signal length monitoring timer 21, 31 ... Dependent station control section 22, 33 ... Break signal length control means 23, 34 ... Break signal length storage section 32 ... Output low level length determining means 35 ... Low level length measurement section

Claims (3)

(57) [Claims] 1. A communication control system in which a plurality of subordinate stations are connected to a control station via a common signal line, and each of the subordinate stations notifies the control station of an interrupt by a break signal.
The control station includes a break signal length table storing a signal length of a break signal assigned to each of the slave stations, and a break signal length measuring unit that measures a signal length of a break signal applied via the signal line. With reference to the break signal length table, a search is made for a subordinate station to which a break signal having a signal length equal to or less than the signal length measured by the break signal length measuring unit is assigned, and a break signal is transmitted to each subordinate station searched. A control station control unit for sequentially outputting an instruction for inquiring whether or not a response indicating that a break signal has been sent is received, wherein each of the dependent stations has a signal of a break signal assigned to its own dependent station. A break signal length storage unit in which a break length is stored and a break length of the signal length stored in the break signal length storage unit when an interrupt factor occurs. A slave station control unit for sending a signal to the signal line and receiving a command from the control station to send a response indicating whether or not the slave station has sent a break signal to the signal line. A communication control method characterized by the following. 2. A communication control system in which a plurality of subordinate stations are connected to a control station via a common signal line, and each of the subordinate stations notifies the control station of an interrupt by a break signal.
The control station includes a break signal length table storing a signal length of a break signal assigned to each of the slave stations, and a break signal length measuring unit that measures a signal length of a break signal applied via the signal line. Searching for a dependent station to which a break signal having the same signal length as the signal length measured by the break signal length measuring unit with reference to the break signal length table, and providing a break signal to each of the found dependent stations. A control station control unit that sequentially outputs a command for inquiring whether or not the slave station has been transmitted until a response indicating that a break signal has been transmitted is received, and each of the dependent stations is assigned to its own dependent station. A break signal length storage unit in which a signal length of the break signal is stored, and whether a break signal is transmitted to the signal line due to occurrence of an interrupt factor By transmitting a break signal having a signal length stored in the break signal length storage unit to the signal line by determining that the signal has not been transmitted, and receiving the command from the control station, A slave station control unit for sending a response indicating whether or not its own slave station has sent a break signal to the signal line. 3. A communication control system in which a control station and a plurality of subordinate stations are connected via a common signal line, and each of the subordinate stations notifies an interrupt to the control station by a break signal.
The control station includes a break signal length table storing the signal lengths of the break signals assigned to the slave stations, and a first break signal for measuring the signal length of the break signal applied via the signal line. A length measuring unit and a dependent station to which a break signal having the same signal length as the signal length measured by the first break signal length measuring unit is assigned with reference to the break signal length table, and A control station control unit for sequentially outputting a command for inquiring whether or not a break signal has been transmitted to the dependent stations until receiving a response indicating that the break signal has been transmitted; A break signal length storage unit in which the signal length of the break signal assigned to the slave station is stored, and a second signal length measuring unit for measuring the signal length of the break signal transmitted to the signal line. The break signal length measurement unit determines whether or not a break signal is sent to the signal line due to the occurrence of an interrupt factor, and if it is determined that a break signal is not sent, the break signal is stored in the break signal length storage unit. The signal length measured by the second break signal length measurement unit is stored in the break signal length storage unit when it is determined that the signal is transmitted. A break signal whose signal length is a difference between the signal length stored in the break signal length storage unit and the signal length measured by the second break signal length measurement unit, provided that the signal length is shorter than the signal length. And a slave station control unit for sending a response indicating whether or not the slave station has sent a break signal to the signal line by receiving the command from the control station. Communication control system to be.