JP2004023130A - Communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication system by which the accuracy of communication is enhanced and a host station obtains detailed data of a particular subordinate station. <P>SOLUTION: When the host station fails to transmit / receive data to / from a second subordinate station while the host station is not connected to fourteenth and fifteenth subordinate stations, the host station again transmits a command to the second subordinate station by utilizing an idle time for a fixed period of the fourteenth subordinate station not connected to the host station so as to await a response from the second subordinate station within the fixed period. Further, when the host station requires detailed data of a fourth subordinate station, the host station uses an idle time for the fixed period of the idle fifteenth subordinate station and automatically transmits message data to the fourth subordinate station within the fixed period to request the fourth subordinate station to return the detailed data. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication system for transmitting and receiving data of a fixed data length at a fixed period from an upper station to a fixed lower station. In particular, the upper station is an upper controller, and the lower station is a servo or I / O. Related to a certain FA system.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as a communication system, there is an FA system in which an upper controller serving as an upper station and servos and I / Os serving as lower stations are connected by a 1: N network, and the upper controller controls servo and I / O. .
[0003]
In this type of FA system, servos and I / Os of up to about 15 stations can be connected to an upper controller as an upper station. , Data of a fixed data length is exchanged.
[0004]
[Problems to be solved by the invention]
However, in the conventional communication system as described above, even when data transmission / reception with a certain lower station fails, nothing is performed until data transmission / reception in the next cycle, and no special retry operation is performed. . In addition, no special retry operation is performed for a lower station having a problem in wiring or the like.
[0005]
In a conventional communication system, an upper station sometimes wants detailed data of a lower station in order to perform servo adjustment or the like. In this case, it is necessary to transmit message data in addition to the command data of the normal command from the upper station to a specific lower station, and request a detailed data return. However, when command data and message data are sent to the same lower station at the same fixed cycle, the lower station may have trouble handling data and may lose data or may take longer to process. is there. It is also conceivable that two station addresses are assigned to the same lower station and command data and message data are transmitted to each station address. However, in such a case, duplication of addresses may occur.
[0006]
An object of the present invention is to provide a communication system capable of improving the accuracy of communication by performing a retry operation on a lower station.
[0007]
Another object of the present invention is to provide a communication system capable of transmitting message data from an upper station to a lower station without causing complicated data handling processing and an increase in data processing time in the lower station. Is to provide.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a communication system according to one aspect of the present invention is a communication system that transmits and receives data having a fixed data length in a fixed cycle from an upper station to a fixed lower station.
When the upper station is not connected to the upper station for the maximum number of times that the lower station can be connected, the upper station uses a fixed time period of the lower station that is not connected to the upper station, and uses this fixed cycle. In this case, the lower station which has failed in data transmission / reception is detected by the hardware of the upper station, and the data transmission / reception is performed again with respect to the lower station.
[0009]
In this configuration, when the number of connected lower stations is small, the upper station uses the fixed time period of the non-connected lower station for the fixed station to send data to the lower station that failed in data transfer. Since data transfer is performed again, the accuracy of communication is improved.
[0010]
In order to achieve the above object, a communication system according to another aspect of the present invention is a communication system that transmits and receives data having a fixed data length in a fixed cycle from an upper station to a fixed lower station,
When the upper station is not connected to the upper station for the maximum number of times that the lower station can be connected, the upper station uses a fixed time period of the lower station that is not connected to the upper station, and uses this fixed cycle. The message data is transmitted / received to / from a specific lower station.
[0011]
In this configuration, when the number of connected lower stations is small, the upper station uses the idle time of the fixed period of the lower station that is not connected to the specific lower station to make detailed Since message data such as a data return request is transmitted / received, detailed data of a specific lower station can be obtained.
[0012]
In order to achieve the above object, a communication system according to still another aspect of the present invention is a communication system that transmits and receives data having a fixed data length in a fixed cycle to a fixed lower station from an upper station.
When transmitting and receiving predetermined data including command data and message data to the same lower station at the same fixed period, the upper station specifies that the message data is included in the predetermined data. Setting bits in the control field information in the predetermined data,
When the lower station confirms that the specific bit is set in the control field information in the predetermined data from the upper station by hardware of the lower station, the lower station changes the access area of the RAM to the message data. Is switched to an access area for use.
[0013]
In this configuration, the lower station determines from the control field information that message data is included, and command data and message data are sent from the upper station at the same fixed cycle to switch the access area of the RAM. Also in this case, the data handling process does not become complicated and the data processing time does not increase, and the RAM is not overwritten. Thereby, the upper station can send command data and message data to the same lower station at the same fixed cycle.
[0014]
In this case, when the upper station is not connected to the upper station for the maximum number of times the lower station can be connected, the upper station uses an available time for a fixed period of the lower station that is not connected to the upper station, The lower station that failed to transfer the predetermined data within the fixed period may be detected by hardware of the upper station, and the lower station may transmit and receive the predetermined data again.
[0015]
In this configuration, when the number of connected lower stations is small, the upper station uses the fixed time period of the non-connected lower station for the fixed station to send data to the lower station that failed in data transfer. Since the exchange of the predetermined data is performed again, the accuracy of the communication is improved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
(1st Embodiment)
FIG. 1 is a block diagram showing the configuration of the communication system of the present invention.
[0018]
Communication system shown in Figure 1, the host controller 1 is a host station, servo _{2 01-2 12} is a lower station (servo _{2 03-2 11} is not shown) and a and I / _{O2 13} cage, to host device 1 are connected by a servo _{2 01-2 12} and I / _{O2 13} and the network. In FIG. 1, only 13 lower stations are connected to the upper controller 1, but it is assumed that up to 15 lower stations can be connected to the upper controller 1.
[0019]
Servo _{2 01-2 12} performs control of the motor _{3 01-3 12,} the station address is 01H～0BH. The station address of the I / O2 ₁₃ is 0CH.
[0020]
FIG. 2 is a diagram showing a basic data flow when a maximum of 15 lower stations are connected to the upper controller 1 in the communication system shown in FIG.
[0021]
The upper controller 1 transmits a command including the station addresses 01H to 0EH as fixed data length data to each lower station having the station address in a fixed cycle, and each lower station transmits a response to the command from the upper controller 1. Reply to host controller 1. In FIG. 2 (the same applies to FIGS. 3 to 5 described below), a solid line indicates a command transmitted from the upper controller 1 to each lower station, and a lower line indicates a response transmitted from each lower station to the upper controller 1. The manner in which data is exchanged between the upper controller 1 and the lower stations of the third to thirteenth stations (station addresses 03H to 0CH) is omitted.
[0022]
Further, the upper controller 1 transmits a command to all lower stations by simultaneous broadcasting (the address at this time is FFH), and each lower station generates an interrupt signal INT at the time of the simultaneous broadcasting, and usually, The CPU waiting for the interrupt is activated by this interrupt signal INT, synchronization is performed, and the processes of all lower stations are simultaneously executed.
[0023]
In the communication system shown in FIG. 1, the maximum number of lower stations that can be connected to the upper controller 1 and the data amounts of commands and responses are the same, and the cycle T for generating the interrupt signal INT is always constant. ing. That is, even when the number of lower stations connected to the upper controller 1 is small, the period T is constant. When the maximum number of lower stations that can be connected to the upper controller 1 is 15, only 13 lower stations are connected. Is connected, the fixed period of the two lower stations that are not connected is idle time.
[0024]
FIG. 3 is a diagram showing a data flow in a conventional communication system in a case where the lower-level stations of the 14th and 15th stations are not connected to the upper-level controller 1.
[0025]
In the conventional communication system, a communication IC (not shown) which is hardware of the upper controller 1 is used when the lower stations of the 14th and 15th stations (station addresses 0DH and 0EH) are not connected to the upper controller 1. Also sends a command to the 14th and 15th subordinate stations.
[0026]
FIG. 4 is a diagram showing a data flow in the case where the 14th and 15th lower stations are not connected to the upper controller 1 in the communication system of the present embodiment.
[0027]
In the communication system according to the present embodiment, a communication IC (not shown), which is hardware of the upper controller 1, transmits and receives data to and from the lower station of the second station (station address 02H) in a lower order. Since no response is returned from the station, the idle time of the fixed period of the 14th lower station which is not connected to the upper controller 1 is used, and a response comes from the 2nd lower station within this fixed cycle. Command is again sent to the second lower station. That is, the communication IC of the upper controller 1 transmits and receives data to and from the lower station that has failed in data transmission and reception again using a free address area that is not set in advance (retry operation). Thereby, the accuracy of communication is improved.
[0028]
Further, the communication IC of the upper controller 1 does not need to increase the number of transmission bytes to be transmitted to each lower station only when detailed data of a specific servo is required for servo adjustment or the like. Similarly to the above, message data is automatically transmitted to the fourth lower station, for example, within the fixed period using the idle time for the fixed period of the 15th station not connected to the upper controller 1. , Request return of detailed data. Note that since there are usually about two lower stations to be targeted, the communication IC of the upper controller 1 switches the target lower station and transmits message data.
[0029]
(Second embodiment)
In each lower station, the load on the CPU is reduced by temporarily storing data received from the upper controller 1 by the communication unit in the RAM, but command data and message data are transmitted from the upper controller 1 to the lower station. When transmitting, the new data overwrites the RAM, erasing the original data.
[0030]
Therefore, the communication system of the present embodiment can transmit command data and message data from the upper controller 1 to the lower station without overwriting the RAM of the lower station by performing the following operation. .
[0031]
FIG. 5 is a diagram showing a data flow when the lower-level stations of the 14th and 15th stations are not connected to the upper-level controller 1 in the communication system of the present embodiment. Note that the configuration of the communication system of the present embodiment is the same as that of FIG.
[0032]
In the communication system of the present embodiment, the communication IC (not shown) of the host controller 1 includes a preframe PF for synchronizing the PLL, a flag F, an address AD, COM as control field information, DATA as a data packet part, A command is transmitted to each lower station in the form of an HDLC transmission format including an ICRC for error checking and a flag F. Since the transmission format of such HDLC is publicly known, detailed description is omitted. COM is composed of one byte consisting of bits D0 to D7. Note that in normal data transmission, the LSB is sent first, so when representing 1-byte data of COM, the LSB and the MSB are exchanged as shown in FIG.
[0033]
Each lower station distinguishes between message data and command data by bit D4 (M / C). When the bit D4 is set, the data becomes the message data. When the data is the message data, n3 to n0 become the message data sequence. This makes it possible to send long message data.
[0034]
That is, in response to a command from the upper controller 1, the lower station detects that the bit D4 is set by the communication IC (not shown) which is hardware of the lower station, and the communication unit writes the bit D4 to the RAM. At times, the access area of the RAM is switched to the message data access area as shown in FIG.
[0035]
Accordingly, even when command data and message data are sent from the upper controller 1 at the same fixed cycle, each lower station may have trouble handling data and may lose data or may take longer to process. And the RAM is not overwritten.
[0036]
Thereby, the upper controller 1 can transmit command data and message data to the same lower station within the same fixed cycle.
[0037]
At this time, since each lower station merely accesses the RAM, there is no need to download data on the way. That is, each lower station can start the CPU by interrupting the simultaneous broadcast, read the command data and the message data only by the CPU accessing the RAM, and transmit the command data and the message data to the upper controller 1. It becomes possible to send.
[0038]
The communication IC of the upper controller 1 is configured to execute the first embodiment when the data transfer with the lower stations of the first and second stations fails while the lower stations of the 14th and 15th stations are not connected to the upper controller 1 according to the first embodiment. Similarly to the above, the idle time of the fixed cycle of the lower station of the 14th station is used, and the command is sent again to the lower station of the 1st station within this fixed cycle, and the idle time of the fixed cycle of the 15th lower station is used. Is sent again to the second lower station within this fixed period. Thereby, the accuracy of communication is improved.
[0039]
【The invention's effect】
According to the communication system according to an aspect of the present invention, the upper station uses the time vacant for the fixed cycle of the lower station that is not connected to the upper station, and the lower station that has failed to exchange data within this fixed cycle. Since the exchange of data with the station is performed again, the accuracy of communication can be improved.
[0040]
Further, according to the communication system according to another aspect of the present invention, the upper station uses the time vacant for the fixed cycle of the lower station that is not connected to the upper station, and uses the specific lower station within this fixed cycle. On the other hand, since the transmission and reception of message data such as a request for returning detailed data is performed, the upper station can obtain detailed data of a specific lower station. Also, when the upper station obtains detailed data of a specific lower station, it is not necessary to increase the number of transmission bytes to be transmitted to each lower station only for that purpose.
[0041]
Further, according to the communication system according to still another aspect of the present invention, when the upper station transmits and receives predetermined data including command data and message data to the same lower station at the same fixed cycle, A specific bit indicating that the message data is included in the control field information in the predetermined data is set, and the lower station switches the access area of the RAM when confirming that the specific bit is set in the control field information. Due to the configuration, even when command data and message data are sent from the upper station in the same fixed cycle, the lower station does not cause complication of data handling processing and increase in data processing time, and The RAM is not overwritten. Thereby, the upper station can send command data and message data to the same lower station at the same fixed cycle. Further, since the RAM is not overwritten, it is possible to suppress an increase in the load on the CPU of the lower station.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a communication system according to the present invention.
FIG. 2 is a diagram showing a basic data flow when a maximum of 15 lower stations are connected to an upper controller in the communication system shown in FIG. 1;
FIG. 3 is a diagram showing a data flow when a lower-level station of the 14th and 15th stations is not connected to a higher-level controller in a conventional communication system.
FIG. 4 is a diagram showing a data flow in a case where the lower-level stations of the 14th and 15th stations are not connected to the upper-level controller in the communication system according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a data flow in a case where a lower station of the 14th and 15th stations is not connected to the upper controller in the communication system according to the second embodiment of the present invention.
FIG. 6 is a diagram illustrating a configuration of a RAM of a lower station in a communication system according to a second embodiment of the present invention.
[Explanation of symbols]
1 host controller _{2 01-2 12} servo ₂ 13 I / O
_{300 to} 3 ₁₂ motors

Claims (4)

In a communication system for transmitting and receiving data of a fixed data length in a fixed cycle from a higher station to a fixed lower station,
When the upper station is not connected to the upper station for the maximum number of times that the lower station can be connected, the upper station uses a fixed time period of the lower station that is not connected to the upper station, and uses this fixed cycle. A communication system comprising: detecting a lower station in which data transmission / reception has failed in the hardware of the upper station; and transmitting / receiving the data to / from the lower station again. In a communication system for transmitting and receiving data of a fixed data length in a fixed cycle from a higher station to a fixed lower station,
When the upper station is not connected to the upper station for the maximum number of times that the lower station can be connected, the upper station uses a fixed time period of the lower station that is not connected to the upper station, and uses this fixed cycle. A communication system for transmitting and receiving message data to and from a specific lower station within the communication system. In a communication system for transmitting and receiving data of a fixed data length in a fixed cycle from a higher station to a fixed lower station,
When transmitting and receiving predetermined data including command data and message data to the same lower station at the same fixed period, the upper station specifies that the message data is included in the predetermined data. Setting bits in the control field information in the predetermined data,
When the lower station confirms that the specific bit is set in the control field information in the predetermined data from the upper station by hardware of the lower station, the lower station changes the access area of the RAM to the message data. Communication system for switching to an access area for communication. When the upper station is not connected to the upper station for the maximum number of times that the lower station can be connected, the upper station uses a fixed time period of the lower station that is not connected to the upper station, and uses this fixed cycle. 4. The communication system according to claim 3, wherein a lower station in which the transmission and reception of the predetermined data fails is detected by hardware of the upper station, and the transmission and reception of the predetermined data to the lower station are performed again.

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