JP2885834B2 - Communication system and communication control method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a communication system for connecting a plurality of communication devices to one another via a communication medium and performing data communication under the control of at least one master station device, and communication control. It is about the method.

[Related Art] In recent years, many small and inexpensive computer application products have appeared with the development of semiconductor technology and the like, and a communication system in which computers are connected to each other via a communication medium has been developed. For this reason, computerization in hospitals, etc. is also progressing, especially systems that automatically measure patients, especially those who need constant monitoring of their condition, and automatically transfer all the measurement results to monitoring rooms or center rooms. Has also appeared.

Of these transfer methods, the transfer capacity of the measurement results by radio wave is limited by the output capacity due to government regulations,
When the distance increases, transfer of measurement data is almost impossible.

Also, in a communication system for transferring measurement data from a bedside to a monitoring room, a center room, or the like via a communication medium, the transfer process uses the communication method of a general-purpose computer as it is.

[Problems to be Solved by the Invention] For this reason, using the same communication control system as these general-purpose computers, data from a plurality of communication devices cannot be uniformly communicated by each device. A situation such as an increase in only the communication amount occurred, and it was not possible to perform appropriate processing while checking the measurement state of each device.

[Means for Solving the Problems] The present invention has been made for the purpose of solving the above problems, and has the following configuration as one means for solving the above problems.

That is, in a communication system in which a plurality of communication devices are connected to each other via a communication medium and perform data communication under the control of at least one master station device, the master station communicates with a communication device connected to the system at a predetermined cycle period. The polling is sequentially performed to collect the transmission request data amount of each communication device, and the transmission permission data amount of each communication device is determined so that the collected transmission amount of each communication device falls within the predetermined cycle period. When polling each communication device, the transmission requesting device has a means for outputting a transmission permission command together with the designation of the amount of transmission data permitted to be transmitted to the communication device, and each communication device has
When a transmission permission command is received from the master station, transmission processing of the permitted data to the desired communication device is performed, and thereafter, the requested data amount from the own communication device in the next cycle is returned to the master station, and the transmission permission is performed. When receiving a polling directed to the own device which is not a command, the device further comprises means for returning a transmission request data amount from the own communication device in the next cycle to the master station, and further,
The specific communication device can transmit a privilege request for directly controlling another communication device from the specific communication device at a predetermined allotted time of each cycle, and the specific communication device permitted to transmit based on the privilege request is another communication device. Means for enabling transmission of the control command.

Then, for example, the communication device that has received the control command from the specific communication device transmits the processing data in accordance with the control from the specific communication device upon receiving the next transmission request permission command addressed to itself.

[Operation] In the above configuration, transmission of data from each communication device is always ensured at a predetermined cycle, and transmission data generated periodically can be transferred to the desired device reliably and efficiently.

Further, a desired connected communication device can be remotely controlled more reliably and more quickly than a specific communication device, and it is possible to sufficiently cope with a case where data from the device is required immediately.

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the drawings.

In the following, a plurality of electrocardiogram analyzers for collecting electrocardiogram waveforms as biological information and analyzing the electrocardiogram waveforms are connected to each other via a LAN (500) serving as a communication medium, and communication of the plurality of electrocardiogram analyzers is performed by one. A communication system managed and controlled by a master station will be described as an example. However, the present invention is not limited to the electrocardiogram analyzing device that processes the electrocardiogram waveform, and is of course applicable to any communication device.

FIG. 1 is a system configuration diagram of an embodiment according to the present invention. In the figure, reference numeral 400 denotes a master station that manages communication control of the present communication system by managing and controlling a transmission right described later, and 411 denotes a master station.
This is a thermal printer connected to 00. In the present embodiment, the control of the master station 400 is mainly described for communication control,
Of course, the master station 400 may be constituted by an electrocardiogram analysis / analysis device similar to other stations. In this case, the same control as, for example, the central monitor 510 may be performed as an electrocardiogram analyzer at the same time as the communication control as a general master station.

Also, 500 is a LAN as a communication medium, 510 is a central monitor connected to the LAN 500, and 511 is a central monitor 5
Recorder for storing electrocardiogram information etc. connected to 10,
Reference numeral 550 denotes a vet side monitor arranged on each vet side. Reference numeral 552 denotes an input box which is an external input interface, and reference numerals 553 to 555 denote lead codes connected to the input box 552. Biological information of a subject on each of two beds can be collected.
The lead codes 553 to 555 are provided at their distal ends with an electrode for detecting biological information (such as an electrocardiographic waveform) and a microphone for collecting heart rate and blood pressure values.

Numeral 560 denotes a telemeter monitor arranged on the veneside, and an input box 570 for the telemeter can be connected to an inductive code like other input boxes, and a collection test from the biological information collectors 573 to 757 of each subject. Information is wirelessly received.

The monitoring devices (510, 550, 560) can mutually transmit and receive the collected information via the LAN 500, and visually recognize the collected information by another device from a central monitor 510 provided in a nurse center or the like by communication control described later. You can check.

Although only one bedside monitor 550 is shown in FIG. 1, up to 24 bedside monitors can be connected.

FIG. 2 is a block diagram of the monitor device having the above configuration. FIG. 2 shows an example of a bedside monitor provided with a recorder. Hereinafter, this bedside monitor will be described as an example.

The hardware configuration of other devices is substantially the same, and only the operation control is slightly different. For example, a central monitor or the like does not have an input box and a guidance code, and other controls are substantially the same.

2, the same components as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the figure, reference numeral 1 denotes a CPU stored in the ROM 2 and for controlling the entire embodiment according to a program shown in FIG. 7, for example.
In the case of the master station 400, communication control is performed according to the program shown in FIG. Reference numeral 2 denotes a ROM for storing fixed parameters and the like used in the present embodiment in addition to the above-mentioned program, 3 a RAM for temporarily storing the progress of processing, and the like, and 5 a DMA for transferring data to and from a connected input / output device. DMA controller for performing, 21 is a display interface that controls the display unit 200, 22 is an operation panel interface that controls the interface with the operation panel 250, 23 is a sound generator that generates an audio signal output from the speaker 120, Reference numeral 25 denotes a setting switch for setting various operation functions of the apparatus of this embodiment, for example, for setting a monitor type and the like. With this setting, which monitor to operate as (which monitor to operate as a central monitor, a bedside monitor, a telemeter monitor, a master station, etc.) is selected.

27 is a printer interface that controls the thermal printer 300, 29 is a LAN interface that controls the interface with the LAN 500, 30 is a controller that controls the interface with the input box 512, and collects biological information as an analog signal from the input box 512. An external input interface for converting into a digital signal, 31 is a timer circuit, 40 is a standby unit for operating the device of this embodiment at the time of power-on even if the power is turned off and consistent with that at the time of power-off, and 45 is a standby unit. Power supply board.

A display unit 200 is equipped with a CRT display device in this embodiment. Reference numeral 250 denotes an operation panel provided on the display surface of the display unit 200, which is a touch panel which is a pressure-sensitive coordinate input device, and is assigned a key function corresponding to the display function.

The control as a general electrocardiogram analyzer having the above configuration is substantially the same as the control of the invention of the patent application (2) “Biological Information Processing System” filed by the present applicant on May 16, 1989. Control. Accordingly, the communication control of the communication system according to the present embodiment having the above configuration will be described below.

In the present embodiment, the master station 400 performs a polling process on all the connection monitoring devices every fixed time cycle (for example, one cycle of 480 msec in the configuration of FIG. 1). As a result, the transmission request data amount of each device is collected, and the transmission request of each device previously collected is transmitted including the transmission right transfer instruction including the data amount permitted to be transmitted.

When each monitor receives a poll addressed to itself from the master station, it checks the amount of data permitted for this polling transmission and transmits the permitted data to the desired communication partner device or after polling. If there is no permitted amount, the own device immediately returns a return frame including the amount of data requested to be transmitted to another device to the master station, and passes control to the master station.

FIG. 3 shows a polling frame format used in this embodiment, and FIG. 4 shows a return frame format for polling of the format from each monitor device.
FIG. 5 shows the format of a data transmission frame from each device to another device.

In the figure, reference numerals 611, 621 and 631 denote control codes, which represent the frame type. 611 indicates that the frame is a polling frame, 621 indicates that the frame is a return frame for the polling frame,
631 is a code indicating that the frame is a data transmission frame.

Reference numerals 612, 622, and 632 denote destination addresses indicating destination devices (transmission destination devices) of the frame, and address values unique to each device are stored. 613, 623, 633 are source addresses indicating the source device that transmitted the frame.

In the polling frame shown in FIG.
4 to 617 are areas for instructing transmission permission data to the destination device, and transmit a transmission request transmitted from the destination device in the previous cycle with a permission flag added only to a transmission request that permits transmission. Things. If there is no transmission request from each device in the case of minimum communication or the like, there is no such area, and the device simply functions as a frame for collecting transmission requests of each device.

In the return frame for the polling of FIG.
Areas 624 to 627 indicate the transmission request data amount which the own apparatus desires to transmit to another apparatus and the transmission destination apparatus.
The figure shows that there are four transmission data. In these four areas, if there is a transmission request, the flag is set to "1", and the "request" stores the requested transmission data amount. In the part where there is no transmission request, the flag is “0”
Is set, and "request" sets dummy data. Further, in addition to the above areas, a configuration may be provided that includes a status information area 628 indicating the state of the device. By adopting this format, the master station can know the status of each device at the time of polling.

Further, in the data transmission frame shown in FIG.
Is an area indicating the data amount of the following TEXT area 639, and 639 is a TEXT area in which transmission data to the destination device is stored.

The communication control of the master station of the apparatus of this embodiment using the above frames will be described below with reference to the flowchart of FIG. 6 and the communication control of the other monitor apparatus with reference to the flowchart of FIG. .

First, communication control of the master station 400 will be described with reference to FIG.

First, the master station 400 performs step S1 when the system is started up.
And collects the devices connected to the LAN 500 and capable of data communication, the connected device configuration including the recorder type in each device, the state of occurrence of an alarm, and the like in the broadcast command or the like.

The collected data of the network configuration and the like can be received not only by the master station 400 but also by all other devices connected to the network, and the received data is sequentially received to update the network configuration in the RAM 3 of the own device. If an alarm is received, the alarm reception is displayed in a predetermined alarm display area of the display unit 200. Therefore, in the system of the present embodiment, by viewing the display on the display unit 200 of all the connected devices, it is possible to confirm the alarm state generated from any of the connected devices, and to take prompt action Becomes

Subsequently, in step S2, a polling frame shown in FIG. 3 is sequentially transmitted to each connection device. And step
In step S3, the return frame shown in FIG. 4 is received, and the transmission request data amount and the device status from each device are stored in a predetermined network management area in the RAM 3. In the following step S4, it is checked whether or not polling of all the connected devices (slave stations) has been completed.
Returning to S2, polling for the next device is performed.

It should be noted that the collection of the network configuration and the like may be performed not at the time of return for each polling but all at once every fixed cycle, and other than that, control may be performed such that only an alarm occurrence state or the like is performed.

On the other hand, when polling of all the connected devices is completed, the process proceeds from step S4 to step S5, in which the amount of transmission request data collected from each slave station is arranged, and the transmission of each device to be permitted to be transmitted in the next cycle is performed. Determine the amount of data. The transmission data amount is determined within a range in which the execution time of the next polling control, the data transmission control, and the like is within a predetermined cycle time even when the data is transmitted. The priority order of the transmission data is determined in advance according to the contents of the transmission data, and is set in order from the one with the highest urgency of the processing.

Subsequently, in step S6, the device status from each slave station collected by a broadcast command or the like is notified to each connected slave station.
As a result, each slave station can recognize the system construction state and the connection device state. Then, in the following step S7, it is checked whether or not the transmission request from each device includes the transmission request of the remote key data. The remote key data transmission request is a request for a specific monitor device to remotely control another monitor device, and has a function of controlling the specific monitor device as if operating an operation panel of another device. In the present embodiment, the remote key data transmission request can be made only by the central monitor 51.
Only 0.

If the transmission request of the remote key data is not included in step S7, the process proceeds to step S11, and the polling frame including the transmission permission according to the transmission request is transmitted to the first device (slave station). The slave station receiving the polling frame generates a transmission frame according to the data transmission format shown in FIG. 5 so as to transmit the permitted communication data as described in detail later when transmission is permitted. Transmit to a predetermined destination device. After performing the transmission processing, the return frame shown in FIG. 4 is transmitted to the master station.
When there is no transmission request or the like and transmission permission is not included, a new return frame shown in FIG. 4 including the transmission request of the own apparatus is immediately generated and transmitted. Therefore, in step S12, master station 400 waits for the return of the transmission right by receiving the return frame from the slave station. If the response frame is not returned within a predetermined time, the process proceeds to step S13, and the slave station is determined to be in a communication disabled state and is treated as leaving the system. Then, the process proceeds to step S16.

On the other hand, when the return frame is received, step S12 is performed.
The process then proceeds to step S15, and the amount of data requested for transmission and the status of the slave station included in the return frame are registered in the management table in the RAM 3 as in step S3. And step
Proceed to S16.

In step S16, it is checked whether polling has been completed for all the devices connected in this cycle. If the device has not yet been polled, the process proceeds to step S17, and the next device to be polled (slave station) Is selected, and the process returns to step S11 to perform polling processing for the next connection device (slave station).

If the polling for all the slave stations is completed in step S16, the process returns to step S5 and shifts to the polling control of the next cycle.

On the other hand, if the remote key data transmission request is included in step S7, the process proceeds to step S20, the key token flag is set, and each cycle is performed in step S21.
To divide. In this embodiment, one cycle is 480 msec, which is divided into four cycles for each 120 msec.
Then, the first fixed time (20 msec in this embodiment) of the four divided cycles is assigned as a key stage for a key token and for communicating key data and the like corresponding to the key token.

Since this is the beginning of the cycle and the key stage, a polling for a key, which is a remote key data transmission permission, is transmitted to the remote key data transmission request transmitting device in a subsequent step S22. And step S2
In steps 3 and 24, it is monitored whether a return frame for the key polling is received or the key stage is completed. In step S23, the reception of the return frame is monitored because the remote-controlled device changes the control code 621 of the return frame to the control code 621 of the return frame in the key stage after the process based on the control from the remote key data transmission device. This is for returning a control code frame indicating that the code area is a key stage return frame.

For this reason, if the return frame for the key stage is received, the process proceeds from step S23 to step S26, where the key token flag is reset, the cycle is divided into four, and the process is shifted to the normal polling process. . Then, the process proceeds to step S11.

When the key stage is completed and the normal polling execution time is reached, the process proceeds from step S24 to step S30, where the slave station is polled, and in step S31 it is monitored that a return frame for polling is received as in step S12. I do. If the response frame is not returned within the predetermined time, the process proceeds to step S40, and as in step S13, it is determined that the slave station is in a communication disabled state, and the process proceeds to step S35 as a withdrawal from the system.

On the other hand, when the return frame is received, step S31 is performed.
The process then proceeds to step S32, and the amount of data requested to be transmitted and the status of the slave station included in the return frame are registered in the management table in the RAM 3, as in step S3. Then, in the following step S35, it is checked whether or not the polling for all the slave stations connected has been completed. When the polling for all the slave stations is completed, the process returns to step S21, and based on the transmission request data amount collected from each slave station, the transmission permission for each slave station in the data communication area in each cycle divided into four is obtained. The data amount is determined, and the status of each slave station is output by broadcast to notify the connected device.

If there is any slave station that has not yet polled in step S35, the process proceeds to step S36, and the next slave station to be polled is selected. Then, in step S37, it is checked whether or not it is the key stage, that is, whether or not it is the beginning of one cycle time divided into four. Step S23 for key stage
Returning to step S30, if it is not the key stage, the process proceeds to step S30.

Through the above processing, communication control optimal for the communication system according to the present embodiment for performing electrocardiogram information analysis processing and the like can be performed. That is, data that constantly occurs at regular time intervals, such as electrocardiogram information, for example, even in a process that must be reliably transferred to the central monitor 510, etc., can be transferred reliably and efficiently. Even when an alarm occurs, this can be reliably notified to each device and can be confirmed. Further, in such a case, the other connected device can be remotely controlled from the specific device, and the status can be grasped more quickly and more reliably.

Next, communication control of each device (slave station) in accordance with the above-described communication control of the master station will be described below with reference to FIG.

In each slave station, in steps S51 to S53, whether there is received data from the connection communication LAN or whether there is a transmission request from the own device, whether the own device is a specific monitor and whether the remote key is pressed or not. To monitor.

In this state, when a transmission request is issued from the own device, the process proceeds from step S52 to step S55, where the generated transmission data is written into the transmission buffer in the RAM 3 and also into the transmission table. Then, the process returns to step S51, and waits for obtaining the transmission right. This transmission table includes a destination address of a transmission destination desired to transmit, a transmission data amount to the apparatus, and a transmission data area. When a polling from a master station described later comes, a transmission request registered in the transmission table is transmitted. Is read and transmitted. In this embodiment, electrocardiogram information, a heart rate, a blood pressure value, and the like, which are periodically generated, are included. Among them, the alarm occurrence measurement value in the above data is set as the highest priority, and then the measurement data in the minimum cycle is continued.

On the other hand, the own device is the above-described specific device (a device capable of remotely controlling another device such as a central monitor), and the other device,
For example, a bedside monitor (only one is shown in FIG. 1, but up to 31 slave stations can be connected to one master station, for example, 24 bedside monitors can be connected), When the user wants to confirm certain measurement data on another predetermined monitor or when he / she wants to remotely control another device, such as when an alarm occurs, the user inputs a remote key. For example, if an alarm occurs on any of the bedside monitors on the network, the alarm sounds and the (other floor) key flashes. By operating the (other floor) key, the display screen can be shifted to the other floor data display screen. As a result, a screen of the collected data from the bedside where the alarm is generated among the connected bedsides is displayed. (If a plurality of floors occur at the same time, the floor with the smallest number is displayed. In that case, the keys on the remaining floors will flash, indicating which other floor is alarming.) For this reason, the collected biological information of the bedside monitor where the alarm has occurred can be displayed as it is, and it can be visually confirmed. Therefore, in such a case, this function is used for inputting the remote key and wishing to grasp the state more minutely.

In this case, the alarm sound from the other floor can be turned on / off by the other floor alarm sound (ON) (OFF) key.

In such a case, the process proceeds from step S53 to step S60, and confirms that the station is a remote key input enabled station, and then proceeds to step S61. If the local station cannot perform remote control, the key input is invalidated and step S5
Return to 1.

In step S61, key data indicating the device address desired for remote operation and the operation content is generated. Then, in step S62, this data is stored in the transmission table and the transmission buffer, and the process returns to step S51 to wait for polling.

On the other hand, if data from the LAN is received, step S
From 51, the flow advances to step S70 to check whether or not the data is addressed to the own station. If the received data is not the own station, step S51
Return to If the data is addressed to the own station, the flow advances to step S71 to check whether or not the received data is a polling frame. If the frame is a polling frame, the flow advances to step S72 to check the transmission permission data amount during the polling. When there is no transmission permission data, the process proceeds to step S75, and when the transmission permission data amount is designated, the process proceeds to step S73.

In step S73, the first transmission data permitted to be transmitted is transmitted to a desired destination device. Then, in step S74, it is checked whether there is any other data whose transmission is permitted. If there is any data whose transmission is permitted, the flow returns to step S73 to transmit the remaining data.

If all data permitted to be transmitted in step S74 has been transmitted, the process proceeds to step S75.

In step S75, a return frame for the polling of the master station is generated and transmitted. The return frame includes a transmission request for data that has not been transmitted yet and that has been registered in the transmission table, and status information (status information) of the own device. Then, the process returns to step S51 to prepare for receiving the next polling.

According to the above control, desired data can be transmitted to a desired device in a predetermined cycle.

On the other hand, if the polling frame has not been received in step S71, the flow advances to step S76 to check whether or not the key polling has been received. This key polling is sent in the first key stage when the own device previously sends a request for transmitting remote key data by the above-mentioned specific device (a device capable of remote control of another device such as a central monitor). It is a thing. If the own device is a specific device and has received the key polling, the flow advances to step S80 to transmit key data for the device to be remotely controlled by the own device to the desired device.

If the key polling has not been received in step S76, the flow advances to step 82 from step S76 to check whether or not key data has been received from the specific device (central monitor). If the key data is received, the process proceeds to step S83, where the same operation as when the own device key specified by the data is input is performed. In the subsequent step S84, a return frame for the operation is generated and the transmission table is generated. And stored in the transmission buffer. Then, in step S85, a return frame for the remote key data is transmitted at the key stage to notify the end of the key stage. This process is performed completely separately from normal transmission / reception control, and the device also performs normal communication control simultaneously with the above control.

As described above, it is possible to quickly respond to the operation of the remote key frequently used in emergency situations, etc.
Appropriate control can be performed even in the event of an emergency.

If the key data is not received in step S83, the process proceeds from step S83 to step S90, where the received data is
The data is stored in a predetermined area in M3 and a process corresponding to the received data is executed. Here, for example, the registration processing of the network table by the reception of the system construction state or the like by the broadcast in step S6 of FIG. 6 is included.
Then, the process returns to step S51.

In this case, the received data is displayed on the display 200, and if the received data has a network configuration or the like, corresponding processing such as performing subsequent data communication control in accordance with the received data is executed.

FIG. 8 shows the details of the normal communication control procedure described above, and FIG. 9 shows the details of the communication control procedure of the key token control.

As described above, according to the present embodiment, it is possible to appropriately cope with a case where transmission data is periodically generated, such as a biological information measuring device installed on each bedside, and urgent transmission is required. And optimal treatment is possible.

Further, a desired connected communication device can be remotely controlled more reliably and more quickly than a specific communication device, and it is possible to sufficiently cope with a case where data from the device is required immediately.

Although the above description has been made with respect to an electrocardiogram information collection / analysis device and the like, the present invention is not limited to the above example, and can be applied to any biological information collection / monitoring device.

Further, it is needless to say that the present invention can be applied to not only all biological information processing apparatuses but also information processing apparatuses requiring general data communication. In particular, it is most suitable for a device in which transmission data is generated at a constant cycle.

[Effects of the Invention] As described above, according to the present invention, a transmission right can be obtained at a constant period, and transmission data that occurs periodically can be reliably and efficiently transmitted to a desired device. .

In addition, efficient communication that can take an appropriate response to an urgent transmission request can be performed.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a biological information processing system according to an embodiment of the present invention, FIG. 2 is a block configuration diagram of a biological information processing device of the present embodiment, and FIG. 3 is a diagram of a polling frame used in the present embodiment. FIG. 4 is a diagram showing a detailed configuration of a return frame used in the present embodiment, FIG. 5 is a diagram showing a detailed configuration of a data communication frame used in the present embodiment, and FIG. FIG. 7 is a flowchart of a communication control operation of a master station in the embodiment, FIG. 7 is a flowchart of a communication control operation of a slave station in the embodiment, FIG. 8 is a diagram showing a normal communication control procedure of the embodiment, and FIG. FIG. 9 is a diagram illustrating a communication control procedure when communication of a key token is performed according to the embodiment. In the figure, 1 CPU, 2 ROM, 3 RAM, 5 DMA controller, 21 display controller, 22 operation panel interface, 27 printer interface, 29 LAN
Interface, 30 ... External input interface, 200 ...
Display unit, 250: operation panel, 300, 511: thermal printer, 400: master station, 500: LAN, 512, 552: input box, 51
3 to 515, 553 to 555: guide code, 510, 550, 560: monitor device, 570: input box for telemeter, 573 to 575: biological information collector.

Claims (3)

(57) [Claims] 1. A communication control method in a communication system in which a plurality of communication devices are connected to each other via a communication medium and perform data communication under the control of at least one master station device, wherein the master station sends a communication request to the system. The connected communication devices are polled sequentially at a predetermined cycle period to collect the transmission request data amount of each communication device, and the transmission of each communication device is performed so that the collected transmission amount of each communication device falls within the predetermined cycle period. Determine the amount of permitted data, specify the amount of data to be allowed to transmit to the requesting communication device, and output a transmission permission command when polling each communication device in the next cycle. When the transmission permission command is received, the transmission processing of the permitted data to the desired communication device is performed,
After that, the requested amount of data transmitted from the own communication device in the next cycle is returned to the master station. In addition to returning to the station, the specific communication device can transmit a privilege request for directly controlling another communication device from the specific communication device at a predetermined allotted time of each cycle, and the transmission is permitted based on the privilege request. A communication control method characterized in that a specific communication device can transmit a control command of another communication device. 2. A communication device, having received a control command from a specific communication device, transmits processing data in accordance with control from the specific communication device upon receiving a next transmission request permission command addressed to itself. The communication control method according to claim 1. 3. A communication system in which a plurality of communication devices are connected to each other via a communication medium to perform data communication under the control of at least one master station device, wherein the master station has a predetermined communication device connected to the system. Polling is sequentially performed in a cycle period, and the transmission request data amount for each communication device is collected,
The transmission permission data amount of each communication device is determined so that the collected transmission amount of each communication device falls within the predetermined cycle period, and transmission is performed to the transmission request communication device at the time of polling each communication device in the next cycle. Means for outputting a transmission permission command together with the specification of the amount of transmission data to be permitted; each communication device performs a transmission process of the permitted data to a desired communication device upon receiving a transmission permission command from the master station;
After that, the requested amount of data transmitted from the own communication device in the next cycle is returned to the master station. Means for sending back a request to the station, and the specific communication device can transmit a privilege request for directly controlling another communication device from the specific communication device at a predetermined allotted time in each cycle, and permit transmission based on the privilege request. A communication system comprising: means for allowing the specified communication device to transmit a control command of another communication device.