JP7324455B2 - Serial communication method and serial communication system - Google Patents

Description

The present invention relates to a serial communication method and serial communication system, and more particularly to a serial communication method and serial communication system for instructing a slave device to latch and release from a master device.

Commands and data are generally exchanged by serial communication between a master device and a slave device, more specifically, between a controller and a sensing device. A serial communication system with such a configuration is described in Patent Document 1 and Non-Patent Document 1.

Japanese Patent Application Laid-Open No. 2004-317261

"Rotary Encoder FA-CORDER(R)" (Catalog Number: T12-1228N58), Tamagawa Seiki Co., Ltd., September 2018

In order to reliably acquire data from a sensing device, there is a method of holding data at a certain timing and acquiring the held data. There is also a method of reading the stored data twice and adopting the data with the same result of the double reading. This holding of data is called latching, and releasing the holding of data is called release.

The above-mentioned Patent Document 1 discloses a technique of single-master/multi-slave communication in a single-master/multi-slave connection system in which a plurality of sensing devices are connected to a single controller through a bus. However, no mention is made of the function of latching (retaining)/releasing data (releasing retention) in the sensing device.

Non-Patent Document 1 above discloses a technique of single-master/single-slave communication in a single-master/single-slave connection system in which a single sensing device is connected to a single controller through a bus. However, no mention is made of the function of latching (retaining)/releasing data (releasing retention) in the sensing device.

Therefore, it is desirable to be able to latch and release data at arbitrary timing in either a serial communication system in a single-master/single-slave connection system or a serial communication system in a single-master/multi-slave connection system. ing.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a serial communication method and a serial communication system capable of holding and releasing data in a sensing device at arbitrary timing based on a command from a controller.

(1) A serial communication method and a serial communication system according to the present invention provide a serial communication between a controller having a serial communication function and one or more sensing devices having a serial communication function according to a communication format. sends to the sensing device a latch command that instructs the sensing device to hold the detected data or a release command that instructs the sensing device to release the detected data in the communication format. , the sensing device retains the detected data in response to a latch command from the controller, and releases the retention of the detected data in response to a release command from the controller.

(2) In the serial communication method and serial communication system according to the present invention, the sensing device responds to the latch command from the controller by transmitting to the controller a command indicating that the holding instruction has been received, and releasing the sensing device from the controller. In response to the command, a command is transmitted to the controller indicating that an instruction to release the hold has been received.

(3) In the serial communication method and serial communication system according to the present invention, the controller includes an inquiry command for inquiring the state of the sensing device in the communication format and transmits the inquiry command to the sensing device, and the sensing device sends the inquiry command to the controller. In response to an inquiry command from the controller, a command indicating that the data is held or a command indicating that the holding has been released is sent to the controller.

(4) In the serial communication method and serial communication system according to the present invention, when the controller transmits a latch command or a release command to the sensing device, the controller includes a sensing device ID that designates one of the sensing devices. The sensing device designated by the device ID retains the sensed data in response to a latch command from the controller, and releases the retention of the sensed data in response to a release command from the controller. Even if the sensing device ID is not specified, when a latch command or a release command specifying all sensing devices is sent from the controller, all sensing devices hold the detected data according to the latch command and detect release the retention of the data that has been stored in response to the release command.

(5) In the serial communication method and serial communication system according to the present invention, the controller is the master device, the sensing device is the slave device, and serial communication is performed between the master device and the slave device.
(6) In the serial communication method and serial communication system according to the present invention, the sensing device transmits held data to the controller in response to a request from the controller.

According to the serial communication method and serial communication system according to the present invention, the controller includes the latch command and the release command in the communication format and transmits them to the sensing device, and the sensing device senses according to the latch command. Since the data is held and the data detected in response to the release command is released, the sensing device can hold and release the data at any timing based on the command from the controller.

1 is a configuration diagram showing the configuration of a serial communication system according to Embodiment 1 of the present invention; FIG. 1 is a configuration diagram showing the configuration of a serial communication system according to Embodiment 1 of the present invention; FIG. 4 is a timing chart showing a communication format of the serial communication system according to Embodiment 1 of the present invention; FIG. 2 is an explanatory diagram showing an example of contents of a communication format of the serial communication system according to Embodiment 1 of the present invention; 4 is a timing chart showing a communication format of the serial communication system according to Embodiment 1 of the present invention; FIG. 2 is an explanatory diagram showing an example of contents of a communication format of the serial communication system according to Embodiment 1 of the present invention; FIG. 3 is an explanatory diagram showing the format of a control field in the communication format used in the serial communication system according to Embodiment 1 of the present invention; FIG. 4 is an explanatory diagram showing contents of a control field in a communication format used in the serial communication system according to Embodiment 1 of the present invention; FIG. 4 is a timing chart showing a communication format of the serial communication system according to Embodiment 1 of the present invention; FIG. 2 is an explanatory diagram showing an example of contents of a communication format of the serial communication system according to Embodiment 1 of the present invention; 4 is a timing chart showing a communication format of the serial communication system according to Embodiment 1 of the present invention; FIG. 2 is an explanatory diagram showing an example of contents of a communication format of the serial communication system according to Embodiment 1 of the present invention; 4 is an explanatory diagram showing the format of a command code field in the communication format used in the serial communication system according to Embodiment 1 of the present invention; FIG. 4 is an explanatory diagram showing the contents of a command code field in the communication format used in the serial communication system according to Embodiment 1 of the present invention; FIG. FIG. 4 is an explanatory diagram showing allocation of command codes in a communication format used in the serial communication system according to Embodiment 1 of the present invention; FIG. 2 is a sequence diagram showing communication procedures of the serial communication system according to Embodiment 1 of the present invention;

An embodiment of a serial communication system according to the present invention will be described below with reference to the drawings. In addition, in each figure, the same code|symbol is attached|subjected to the same part.

Embodiment 1.
First, in Embodiment 1 of the present invention, a basic configuration of a serial communication system that executes a serial communication method will be described with reference to FIG.

[Structure of serial communication system 1A]
FIG. 1 is a configuration diagram showing the configuration of a serial communication system 1A according to Embodiment 1 of the present invention. In FIG. 1, a serial communication system 1A that implements a serial communication method comprises a controller 10, a device 20, and a communication line 30A. The controller 10 is a master device and the device 20 is a slave device, which are communicably connected through a communication line 30A.

Here, in the serial communication system 1A shown in FIG. 1, a single device 20 is connected to a single controller 10 through a communication line 30A, forming a single master/single slave connection serial communication system. ing.
Single master/single slave communication is performed between the controller 10 and the device 20 in the single master/single slave serial communication system 1A. That is, commands and data are transmitted and received through serial communication between the controller 10, which is a master device, and the device 20, which is a slave device.

The controller 10 has a serial communication function, and is a control unit that reads data from the device 20 through serial communication. The device 20 is a sensing device having a serial communication function, and corresponds to, for example, a sensing device that outputs data detected from a controlled object through serial communication.

The communication line 30A is composed of a signal line for supplying the power supply Vcc, a signal line for maintaining the potential of the ground GND, and a signal line for transmitting a pair of differential transmission signals SD+/SD-.

A power supply Vcc is supplied from the controller 10 to the device 20 through a signal line. The differential transmission signals SD+/SD- are bidirectionally transmitted through signal lines, and are transmitted from the controller 10 to the device 20 and from the device 20 to the controller 10. There is

[Structure of serial communication system 1B]
Next, in Embodiment 1 of the present invention, the basic configuration of the serial communication system 1B that executes the serial communication method will be described with reference to FIG. FIG. 2 is a configuration diagram showing the configuration of the serial communication system 1B according to Embodiment 1 of the present invention.

In FIG. 2, serial communication system 1B mainly includes controller 10, device 20, and bus communication line 30B. The controller 10 is a master device and the device 20 is a slave device, which are communicably connected through a bus communication line 30B. The device 20 as a slave device comprises a plurality of devices 20_1, 20_2, . . . , 20_n.

Here, in the serial communication system 1B shown in FIG. 2, a plurality of devices 20, that is, devices 20_1, 20_2, . ing. This constitutes a single-master/multi-slave serial communication system.

Single-master/multi-slave communication is performed between the controller 10 and the device 20 in the single-master/multi-slave serial communication system 1B. That is, commands and data are transmitted and received by serial communication between the controller 10, which is a master device, and one of the devices 20_1 to 20_n, which are slave devices, 20_i.

In order to identify the plurality of devices 20_1, 20_2, . This device ID may be a number in order such as 1, 2, 3, .

The controller 10 can identify a plurality of devices 20_1, 20_2, . A plurality of devices 20_1, 20_2, .

[Description of communication format (1)]
Next, the communication format of the serial communication method executed in the serial communication system 1A according to Embodiment 1 of the present invention will be described with reference to FIGS. 3 and 4. FIG. Also, the communication format of the serial communication method executed in the serial communication system 1B according to Embodiment 1 of the present invention will be described with reference to FIGS. 5 and 6. FIG.

FIG. 3 is a timing chart showing a communication format of the serial communication system 1A according to Embodiment 1 of the present invention. FIG. 4 is an explanatory diagram showing an example of the contents of the communication format of the serial communication system 1A according to Embodiment 1 of the present invention.

First, the state of communication in the single master/single slave connection serial communication system 1A will be described with reference to FIG. FIG. 3(a) shows transmission of a request from the controller 10 to the device 20 in the single master/single slave serial communication system 1A. Here, the request transmitted by the controller 10 means a request for data to the device 20, as will be described later.

The controller 10 monitors whether or not there is an idle state for one data frame or more from the last part of the preceding data frame, and the idle state for one data frame or more continues from the last part of the preceding data frame. After that, the control field CF is transmitted to the device 20 as a request. One data frame is a unit of a series of data transmitted from the device 20 to the controller 10 .

FIG. 3B shows a communication format of data transmitted from the device 20 to the controller 10 in the single master/single slave serial communication system 1A.

The device 20 determines that communication has started when the control field CF is sent as a request after the idle state continues for one data frame or more. As a result, the device 20 avoids erroneously determining that another communication has started communication.

When the device 20 receives the control field CF as a request from the controller 10, the device 20 transmits data to the controller 10 by serial communication according to the communication format. The device 20 is a sensing device and transmits data sensed from the controlled object to the controller 10 .

The device 20 transmits a series of data including a control field CF, a status field SF, data fields DF0 to DFn, and a check field CRC to the controller 10 according to the communication format, as shown in FIG. 3(b). .

FIG. 4 shows the contents of each field of the data shown in the timing charts of FIGS. 3(a) and 3(b). The control field CF is command information for the communication partner. The status field SF is device status identification information. Data fields DF0 to DFn are information assigned to data IDs. The check field CRC is error check information by CRC (Cyclic Redundancy Check) for all bits except the start bit and delimiter of all fields other than the CRC field.

Next, the state of communication in the single-master/multi-slave serial communication system 1B will be described.

FIG. 5(a) shows transmission of a request from the controller 10 to any one of a plurality of devices 20_1 to 20_n in the single-master/multi-slave serial communication system 1B. Here, a request sent by the controller 10 means a data request to the device 20 .

As in the above description, after the idle state for one data frame or more continues from the last part of the preceding data frame, the controller 10 transfers the control field CF and the device ID field IDF to the devices 20_1 to 20_n. It is transmitted as a request to one of the devices 20_i.

(b) of FIG. 5 shows a communication format of data transmitted from the device 20 to the controller 10 in the single-master/multi-slave serial communication system 1B.

The plurality of devices 20_1 to 20_n determine that communication has started when the control field CF and device ID field IDF are sent as a request after the idle state continues for one data frame or more.

When the control field CF and the device ID field IDF are sent as a request from the controller 10, the plurality of devices 20_1 to 20_n respond to the contents of the control field CF and the contents of the device ID field IDF. Determine if it is a request.

The device 20_i that has determined that the request from the controller 10 is addressed to itself transmits the data to the controller 10 by serial communication according to the communication format. The device 20_i is a sensing device and transmits data sensed from the controlled object to the controller 10 .

As shown in FIG. 5(b), the device 20_i transmits a series of data including a control field CF, a device ID field IDF, a status field SF, data fields DF0 to DFn, and a check field CRC according to the communication format. Send to the controller 10 .

The contents of each field of the data shown in the timing charts of FIGS. 5(a) and 5(b) will be described with reference to FIG. FIG. 6 is an explanatory diagram showing an example of the contents of the communication format of the serial communication system 1B according to Embodiment 1 of the present invention. Unlike the one shown in FIG. 4, FIG. 6 further has a device ID field IDF that is device ID (identification) information for identifying a plurality of devices.

Next, the control field CF in the communication format used in serial communication according to Embodiment 1 of the present invention will be described with reference to FIGS. 7 and 8. FIG.

FIG. 7 is an explanatory diagram showing the format of the control field CF in the communication format used in the serial communication systems 1A and 1B according to Embodiment 1 of the present invention. The control field CF includes a start bit, a SYNC (Synchronous) code bit, a data ID code bit, a data ID parity bit, and a delimiter bit.

FIG. 8 is an explanatory diagram showing the contents of each bit of the control field CF in the communication format used in the serial communication systems 1A and 1B according to Embodiment 1 of the present invention.

The start bit is a bit that indicates the start position, and is fixed to "0", for example. The SYNC code is a predetermined code used for synchronization, and repeats "0" and "1" a predetermined number of times. In this embodiment 1, the SYNC code is assigned a first SYNC code "010" for single-master/single-slave communication and a second SYNC code "101" for single-master/multi-slave communication. be done.

The data ID code is a code to which communication data and operation commands are assigned in order to select communication contents. A data ID code can be assigned a latch/release control execution ID to execute a latch that holds data and a release that releases the latch. Data ID parity is a parity check bit for the data ID code. The delimiter is a bit indicating the end position, and is fixed to "1", for example.

The above SYNC code in the control field CF determines whether single master/single slave communication or single master/multi-slave communication is to be performed in serial communication systems 1A and 1B. The SYNC code, whether "010" or "101", is also used for original synchronization purposes.

In single master/single slave communication, after receiving the control field CF, the device 20 returns data or performs various operations according to the data ID code.

In single-master/multi-slave communication, when the device ID field IDF is transmitted from the controller 10 following the control field CF, the device 20_i having the corresponding device ID returns data or performs various operations according to the data ID code. to run.

[Description of communication format (2)]
Next, communication formats including commands for latching and releasing data in the device 20 according to instructions from the controller 10 will be described with reference to FIGS. 9 to 12. FIG. Note that a latch means holding data not only in a flip-flop circuit but also in various circuits. "Release" means releasing data held by a latch in various circuits.

FIG. 9 is a timing chart showing the communication format of the serial communication system 1A according to Embodiment 1 of the present invention. FIG. 10 is an explanatory diagram showing an example of the contents of the communication format of the serial communication system 1A according to Embodiment 1 of the present invention. In FIGS. 9 and 10, the same parts as in FIGS. 3 and 4 which have already been described are given the same reference numerals to omit redundant description, and the description will focus on the parts different from FIGS.

First, the state of communication including latch and release commands in the single master/single slave connection serial communication system 1A will be described with reference to FIG.

As shown in FIG. 9A, after the idle state for one data frame or more continues from the last part of the preceding data frame, the controller 10 sets the control field CF, the command code field CCF, and the check field CRC. The contained series of data are transmitted to the device 20 .

The device 20 determines that communication has started when a series of data including the control field CF, command code field CCF, and check field CRC is sent from the controller 10 . The device 20 transmits a series of data including a control field CF, a status field SF, a command code field CCF, and a check field CRC to the controller 10 according to the communication format, as shown in FIG. 9(b).

FIG. 10 shows the contents of each field of the data shown in the timing charts of FIGS. 9(a) and 9(b). The control field CF is command information for the communication partner. The status field SF is device status identification information. The command code field CCF is a command code indicating acceptance of an instruction relating to latch or release. The check field CRC is error check information by CRC (Cyclic Redundancy Check) for all bits except the start bit and delimiter of all fields other than the CRC field.

The controller 10 can include command information for instructing the device 20 to execute latch/release control in the data ID code in the control field CF. The controller 10 can further include command codes instructing latch execution and release execution as latch/release related command codes in the data in the command code field CCF.

When the control field CF from the controller 10 is command information instructing the execution of latch/release control and the command code field CCF contains a latch/release-related command code, the device 20 ( b), according to the communication format, send a series of data to the controller 10 including a control field CF, a status field SF, a command code field CCF and a check field CRC;

When the device 20 transmits to the controller 10 as described above, the command code field CCF includes a command code indicating acceptance of the latch or release command from the controller 10 . The device 20 then executes latching or releasing as instructed by the controller 10 .

Next, communication including latch and release commands in the single-master/multi-slave serial communication system 1B will be described with reference to FIG. FIG. 11 is a timing chart showing the communication format of the serial communication system 1B according to Embodiment 1 of the present invention.

As shown in FIG. 11(a), the controller 10, after the idle state for one data frame or more continues from the last part of the preceding data frame, controls field CF, device ID field IDF, command code field CCF, and a check field CRC to one of the devices 20_1 to 20_n.

A plurality of devices 20_1 to 20_n determine that communication is started when a series of data including a control field CF, a device ID field IDF, a command code field CCF, and a check field CRC are sent from the controller 10. do.

A plurality of devices 20_1 to 20_n determine whether the request is addressed to itself according to the contents of the control field CF and the contents of the device ID field IDF. The device 20_i determined to correspond to the device specified by the device ID field IDF follows the communication format as shown in FIG. A series of data is sent to the controller 10 including the CCF and the check field CRC.

The contents of each field of the data shown in the timing charts of FIGS. 11(a) and 11(b) will be described with reference to FIG. FIG. 12 is an explanatory diagram showing an example of the content of the communication format of the serial communication system 1B according to Embodiment 1 of the present invention. FIG. 12 differs from that shown in FIG. 10 in that it has a device ID field IDF that is device ID information for identifying a plurality of devices.

The controller 10 can include command information that instructs the device 20_i to execute latch/release control in the data ID code in the control field CF. The controller 10 can further include the ID of the device instructing the execution of the latch/release control in the device ID field IDF, and the command code related to latch/release in the command code field CCF. Here, the latch-related command code is a command code that instructs latch execution, a target device for latch execution, release execution, and a target device for release execution.

In the device 20_i, the control field CF from the controller 10 is command information indicating the execution of latch/release control, the data in the command code field CCF includes a latch/release-related command code, and the device ID field If the device corresponds to the device instructed to execute latch/release control by the IDF, as shown in FIG. A series of data containing the CRC is sent to the controller 10 .

If the device 20_i corresponds to the device instructed to execute the latch/release control by the device ID field IDF, the device 20_i has received the latch or release instructed by the controller 10 at the time of the above transmission to the controller 10. is included in the command code field CCF. The device 20_i then executes latching or releasing as instructed by the controller 10 .

Next, the command code field CCF in the communication format used in serial communication according to Embodiment 1 of the present invention will be described with reference to FIGS. 13 and 14. FIG. FIG. 13 is an explanatory diagram showing the format of the command code field CCF in the communication format used in the serial communication systems 1A and 1B according to Embodiment 1 of the present invention. The command code field CCF includes a start bit, a command code field CCF bit, and a delimiter bit.

FIG. 14 is an explanatory diagram showing the contents of each bit of the command code field CCF in the communication format used in the serial communication systems 1A and 1B according to Embodiment 1 of the present invention. The start bit is a bit that indicates the start position, and is fixed to "0", for example. The bits of the command code field CCF are, for example, 8 bits and can take 256 different values from 0x00 to 0xFF. The delimiter is a bit indicating the end position, and is fixed to "1", for example.

Next, specific code contents of the command code field CCF in the communication format used in serial communication according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 15 is an explanatory diagram showing allocation of command codes in the communication format used in the serial communication systems 1A and 1B according to Embodiment 1 of the present invention.

An example of assignment of command codes shown in FIG. 15 is as follows.
A command code 0x00 from the controller 10 is an instruction to execute release for all of the plurality of devices 20_1 to 20_n.
A command code 0x00 from the device 20 side indicates acceptance of a release execution instruction for all of the plurality of devices 20_1 to 20_n.

A command code 0x55 from the controller 10 is an instruction to execute a release for the device 20_i, which is one of the devices 20_1 to 20_n.
A command code 0x55 from the device 20 side indicates acceptance of a release execution instruction for the device 20_i, which is one of the devices 20_1 to 20_n.

The command code 0x5F from the device 20 side indicates that one of the devices 20_1 to 20_n, the device 20_i, is latching and holding data. command code is sent from the controller 10.
The command code 0x50 from the device 20 side indicates that one of the devices 20_1 to 20_n, the device 20_i, is being released and has released the hold. Sent when a code is sent from the controller 10.

A command code 0xAA from the controller 10 is an instruction to execute a latch for the device 20_i among the plurality of devices 20_1 to 20_n.
A command code 0xAA from the device 20 side indicates reception of a latch execution instruction to one of the devices 20_1 to 20_n, the device 20_i.

A command code 0xFF from the controller 10 is a latch execution instruction for all of the plurality of devices 20_1 to 20_n.
A command code 0xFF from the device 20 side indicates acceptance of a latch execution instruction for all of the plurality of devices 20_1 to 20_n.

In the above case, when a latch or release instruction is issued to all of the plurality of devices 20_1 to 20_n, all the devices 20_1 to 20_n operate according to the latch or release instruction. One of the determined devices 20_j may transmit a command code for acceptance to the controller 10 .

In the above case, if an unspecified device ID is specified in the device ID field IDF and a latch command or release command specifying all the devices 20_1 to 20_n is transmitted from the controller 10, all the devices 20_1 to 20_n are Operates according to the instructions of the latch command or release command.

The communication including the latch and release commands in the single-master/multi-slave serial communication system 1B described above can also be applied to the single-master/single-slave serial communication system 1A. In the case of the serial communication system 1A, there is only one device 20 and there is no device specification, so the controller 10 and the device 20 may use one of the command codes in FIG.

[Communication procedure in serial communication system 1B]
Next, the communication procedure of the serial communication method executed in the serial communication system 1B according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 16 is a sequence diagram showing communication procedures of the serial communication system 1B according to Embodiment 1 of the present invention.

Here, in the serial communication system 1B, a plurality of devices 20_1 to 20_n are connected in parallel to the controller 10 through the bus communication line 30B. A plurality of devices 20_1 to 20_n are sensing devices, and are configured to be able to latch, detect, and unlatch data on controlled objects. Assume that the device 20_a determined as the representative device is determined to transmit an acceptance to the controller 10 when the controller 10 instructs all devices to execute latch or release.

First, as shown in (a1) of FIG. 16, the controller 10 transmits a latch execution instruction to the device 20_m via the bus communication line 30B.
When the device 20_m receives the latch execution instruction from the controller 10, the device 20_m transmits to the controller 10 that it has accepted the instructed latch, and executes the instructed latch, as shown in (b1) of FIG. retains the data detected by

After receiving the latch acceptance corresponding to the latch instruction, the controller 10 transmits the request instruction to the device 20_m via the bus communication line 30B, as shown in (a2) of FIG.
Upon receiving the request instruction from the controller 10, the device 20_m transmits the data detected from the controlled object to the controller 10 as shown in (b2) of FIG.

After acquiring the data in response to the request, the controller 10 transmits a release execution instruction to the device 20_m via the bus communication line 30B, as shown in (a3) of FIG.
When the device 20_m receives the release execution instruction from the controller 10, the device 20_m transmits to the controller 10 that the instructed release has been accepted, and executes the instructed release, as shown in (b3) of FIG. to release the latch.

As shown in (a4) of FIG. 16, the controller 10 transmits a latch execution instruction to all of the plurality of devices 20_1 to 20_n via the bus communication line 30B.

When the device 20_a determined as the representative device receives from the controller 10 instructions to execute latching for all of the devices 20_1 to 20_n, as shown in (b4) of FIG. A notification of acceptance is sent to the controller 10, and the instructed latch is executed to hold the detected data.

In parallel with the latch execution of the device 20_a described above, other devices than the device 20_a also receive the latch execution instruction for all the devices from the controller 10, and execute the instructed latch all at once for detection. retains the data

After receiving the latch acceptance from the representative device 20_a in response to the latch instruction for all devices, the controller 10 issues a request to the device 20_a as shown in (a5) of FIG. Instructions are sent via bus communication line 30B.
Upon receiving the request instruction from the controller 10, the device 20_a transmits the detected data to the controller 10 as shown in (b5) of FIG.

After receiving the data from the device 20_a, the controller 10 transmits a request instruction to the device 20_b via the bus communication line 30B, as shown in (a6) of FIG.
Upon receiving the request instruction from the controller 10, the device 20_b transmits the data detected from the controlled object to the controller 10 as shown in (b6) of FIG.

After receiving data from the device 20_n-1 in the same way, the controller 10 transmits a request instruction to the device 20_n via the bus communication line 30B, as shown in (a7) of FIG.
Upon receiving the request instruction from the controller 10, the device 20_n transmits the data detected from the controlled object to the controller 10 as shown in (b7) of FIG.

The controller 10 transmits requests to all of the devices 20_1 to 20_n as described above, and receives data in response to the requests. . . . send a release execution instruction to all of the devices 20_n via the bus communication line 30B.

When the device 20_a determined as the representative device receives an instruction to execute release for all of the devices 20_1 to 20_n from the controller 10, as shown in (b8) of FIG. The reception is transmitted to the controller 10, the instructed release is executed, and the latch is released.

In parallel with the release execution of the device 20_a, the devices other than the device 20_a also receive instructions from the controller 10 to execute the release for all the devices, and simultaneously execute the instructed releases. Release the latch.

In the above explanation using the sequence diagram of FIG. 16, a specific example is given of a case where there are a plurality of devices 20_1 to 20_n. However, even in the case of a single device 20, It is possible to perform latch, data transmission and release.

According to the first embodiment, at arbitrary timing, the controller 10 transmits the latch command and the release command in the communication format to the plurality of devices 20_1 to 20_n. 20_n can hold the detected data in response to the latch command, and can release the holding of the detected data in response to the release command.
Therefore, data can be held and released in the plurality of devices 20_1 to 20_n based on commands from the controller 10 at arbitrary timing.

As described above, the plurality of devices 20_1 to 20_n simultaneously execute latching according to an instruction from the controller 10, and then transmit data according to an instruction from the controller 10. The transmitted data is in a state of synchronicity.

Therefore, the first embodiment can be applied to applications that require synchronism of data detected by a plurality of devices 20_1 to 20_n.

In addition, since the plurality of devices 20_1 to 20_n are simultaneously latched by an instruction from the controller 10, an application that reads the data twice in the plurality of devices 20_1 to 20_n and confirms matching , the first embodiment can be applied.

[Other embodiments]
In the description of the serial communication systems 1A and 1B of Embodiment 1 above, the communication line 30A or the bus communication line 30B uses a pair of RS485 standard SD+ and SD using two equal signal lines for signal transmission. Although the example is shown assuming communication using differential transmission signals of -, the present invention is not limited to this content. For example, the serial communication systems 1A and 1B according to Embodiment 1 of the present invention may be applied to communications according to the RS422 standard or the RS232 standard. Also, the serial communication systems 1A and 1B according to the first embodiment of the present invention may be applied to communication that does not rely on differential transmission signals.

In the above description of the serial communication method of the first embodiment, specific examples of the communication format, internal field configuration, bit configuration, command code, etc. have been described, but the content is not limited to these.

In the above description of the serial communication method of the first embodiment, an example has been given assuming an asynchronous communication mode as serial communication, but the communication mode is not limited to this.

3 and 9 in the serial communication system 1A of the first embodiment, communication is shown without the device ID field IDF, but the device ID field IDF is added immediately after the control field CF. state can be communicated.

1A, 1B serial communication system, 10 controller, 20 device (sensing device), 20_1 to 20_n multiple devices (multiple sensing devices), 30A communication line, 30B bus communication line.

Claims (6)

A serial communication method for performing serial communication according to a communication format between a controller having a serial communication function and one or more sensing devices having a serial communication function,
The controller includes, in the communication format, a latch command instructing the sensing device to hold the detected data or a release command instructing the sensing device to release the holding of the detected data. to the device,
The sensing device is
holding the detected data in response to the latch command from the controller;
canceling retention of the detected data in response to the release command from the controller;
The controller includes an inquiry command for inquiring the state of the sensing device in the communication format and transmits the inquiry command to the sensing device,
The serial communication method, wherein the sensing device transmits to the controller a command indicating that the data is held or a command that indicates that the holding is released in response to the inquiry command from the controller. The sensing device is
transmitting to the controller a command indicating acceptance of a hold instruction in response to the latch command from the controller;
2. The serial communication method according to claim 1, wherein in response to said release command from said controller, a command indicating acceptance of an instruction to cancel holding is transmitted to said controller. The controller includes a sensing device ID designating one of the sensing devices when transmitting the latch command or the release command to the sensing device,
The sensing device designated by the sensing device ID,
holding the detected data in response to the latch command from the controller;
3. The serial communication method according to claim 1, wherein retention of said detected data is released in response to said release command from said controller. wherein the controller is a master device and the sensing device is a slave device;
4. The serial communication method according to claim 1, wherein said serial communication is performed between said master device and said slave device. 5. The serial communication method according to claim 1, wherein said sensing device transmits said held data to said controller in response to a request from said controller. A controller having a serial communication function and one or more sensing devices having a serial communication function,
A serial communication system that performs serial communication between the controller and one or more of the sensing devices by the serial communication method according to any one of claims 1 to 5.

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