JPS59134943A - Data communication system - Google Patents

Abstract

PURPOSE:To shorten a communication cycle by communicating slave stations of all addresses at application of a power supply of a system and discriminating a slave station not mounted and making communication depending on the presence of returned information. CONSTITUTION:When the power supply is applied at the start of data communication polling and selecting are performed the same as normal communication. The transmission terminal subject to polling and the receiving terminal subject to selecting return signals to the control station data and a start bit ST as shown in Figs. B, C, then the control station confirms the presence of the start bit ST and checks whether the transmitting and receiving terminals are set correctly or not in pairs from the result and when it is normal, the address map of the mounted slave station is formed and when it is abnormal, displays this facts. Then, the communication is performed according to the address map.

Description

Detailed Description of the Invention The present invention provides a system for cyclically communicating data between a control station (mount control unit) and one or more dependent stations (transmitting terminal, receiving terminal) by polling and selecting. Regarding click data communication system. In this type of system, it is desirable to make the data communication cycle as short as possible.

Generally, the number of dependent stations (number of address numbers) that can be accommodated in such a system is predetermined, and therefore, conventionally, polling and selection are usually performed according to the number of dependent stations that can be accommodated. It is. In this case, if the number of address numbers is N and the communication time per address is T, then the communication time for one cycle is NXT. By the way, during actual use, the number of dependent stations actually accommodated varies depending on the system, and there are dependent stations that are not implemented. Therefore, in the conventional method, ringing and selecting are performed for this unimplemented address, which is not preferable as it includes unnecessary communication time.On the other hand, in consideration of this situation, dependent stations I can't think of a way to store the implementation status in R, AM (Random Access Memory), etc. in advance, but this method not only requires correction every time the number of steps is increased, but also makes the work complicated. It has the disadvantage of being.

This invention has been made under such circumstances, and aims to shorten one communication cycle by easily identifying uninstalled dependent stations and communicating with them, without performing the above-mentioned complicated operations. Its features are: - When the system is powered on, it communicates with slave stations at all addresses, checks the implementation address number based on the presence or absence of information returned from each slave station, and then performs the specified data communication. Hereinafter, embodiments of the present invention will be explained with reference to the drawings. Figure 1 is a block diagram showing an overview of a data communication system according to the present invention, and Figure 2 is a subordinate diagram of Figure 1. FIG. 3 is a block diagram showing the configuration of the station in detail, FIG. 3 is a block diagram showing the configuration of the control station (control unit) in detail, and FIG. tM4 is an explanatory diagram explaining the transmission information format. In FIG. 1, 111*112 e113... is a transmitting terminal, 121 e 122 + 123... is a receiving terminal, 2 is a control station, and l is a common signal line. Here, the transmitting terminal 111, the receiving terminals 121, 112, and 12
2. 113 and 123 are installed as a pair and given the same address. Therefore, for example, data from the transmitting terminal 111 is sent to the control unit 2 by polling, and is given to the corresponding receiving terminal 121 by selecting from the unit 2, so that the receiving terminal 121 receives a predetermined number based on the data. Operating the equipment〇The transmitting and receiving terminals are 1 waveform shaping section 11 as shown in Fig. 2.
, read timing pulse generation section 12, address verification section 13, shift register 14, command discrimination section 15, check of two consecutive data transmissions or 2/3 (2 out of
3) Verification circuit 161 that performs checking; output circuit 17 that latches only verified data and outputs it to external equipment; input section 181 for on/off signals; and converts analog input values into digital values (A/D conversion). Input section 18 consisting of conversion section 182, parallel/serial conversion section 19, switch SW1
．． Consists of SW2, driver circuit, etc.

On the other hand, the control unit, as shown in FIG.
CPU) 22, memory 23 including RAM or ROM,
It is composed of an input/output circuit 24, an external device 25, a driver circuit 26, a data reading circuit 27, etc. Therefore, information from the CPU 22 is sent to the slave station U1 via the input/output circuit 24 and driver circuit 26, and
Data from the dependent station is provided to the CPU 22 via the data reading circuit 27 and the input/output circuit 24.Here, the operation of the dependent station will be mainly explained with reference to FIGS. 1 to 4.

The data communication mode is divided into an information collection mode in which data is collected from a transmitting terminal, and a control mode in which the collected control data is transmitted to a receiving terminal. There are two types of data collection: Anajig data collection via 182, and digital data collection via the on/off manual section 18s, and this information is stored in advance in the address section or command section shown in Figure 4 (a). Sera) and sent to the subordinate station. Therefore, when the control station sends out information as shown in FIG. Based on the timing pulse from the pulse generator 12, the information (serial) is read into the shift register 14 and converted into parallel information. Since the first signal sent from the control station is a star (signal ST), the dependent station is reset to the initial state by this start signal, and the set address (
It is set in advance using a switch called a dip switch. ), the address matching unit 13 determines whether the requested data is analog data or digital data. Note that the address and command signals are subjected to parity check using, for example, odd parity. In the slave station with the matching address, the command determination unit 15 continues to determine the command signal sent from the control station, and when it is in the information collection mode, it inputs ON/OFF manually or analog input via the input unit 18. A/D convert and read. These data are converted into serial data by the parallel/serial converter 19 and sent to the control station via the driver DR, the common signal line, and the common signal line. The format of the signal sent from the slave station to the control station during the information collection mode is as shown in Figure 4 (←), in which the control data includes a start bit (ST) and a stop bit (ST).
It is configured with SP attached. Further, error checking in the information gathering mode is performed by parity check and double transmission verification. However, if the two times of data do not match, one more communication is performed and the determination is made by a 2/3 check. In other words, even though the dependent station is returning normal data, a signal error may occur due to transmission noise, etc., so it is better to terminate communication with the dependent station three times than to terminate communication with the relevant dependent station after only two times. This is because it is thought that the probability of receiving data will be higher if the majority decision is made by 2/3. Note that this 2/3 majority decision is made by the arithmetic and control unit (CPU) installed in the control station.
) can be easily done. On the other hand, when the above command signal indicates the control mode, the dependent station (receiving terminal) at the corresponding address receives the control data collected by the control station as described above. In order to make a determination based on double transmission verification in the circuit 16, the control station transmits the same data at least twice in succession. Only when the verification circuit 16 receives the same data twice in succession, it latches the data into the digital output circuit 17 and outputs it to the external device via the terminal T2, and also outputs the data to the external device via the terminal T2.

The format of the signal at this time is returned to the control station via the parallel/serial converter 19 and driver DR, as shown in FIG. It is constructed by adding a start pitch of 8T and a stop pitch of SF. Note that the receiving terminal also returns data to the control station for the first data sent from the control station, but in this case, the verification circuit 1
Since the data does not match in step 6, the matching data will be returned after checking one cycle before. 1 Therefore, the data sent from the control station the first time and the data sent back from the dependent station will be different. There is not necessarily a corresponding relationship between them. In addition, the data sent from the control station side is temporarily stored in the matching circuit, so if the first and second data are different from each other, the data of 1 becomes the internally stored data, and the control output changes. I don't, but
The control station compares the transmitted data and the returned data, and if there is a discrepancy, it
If communication is performed one more time, it becomes easier for the control station to detect data abnormalities, and reliability can be improved.

FIG. 5 is an explanatory diagram for explaining the operation at the control station.

That is, in starting the data communication as described above,
The control station performs the following operations. As shown in the figure, when the power is turned on (■), the control station determines the transmission rate as necessary (0). Next, the control station performs polling and selection in the same way as during normal data communication as described above.

The polled transmitting terminal and the selected receiving terminal reply to the control station with predetermined data and a start bit ST as shown in Figure 4←) and (c), so the control station sends a response to the specified address. (Reply star) Check the presence of bit ST6), and check whether the sending and receiving terminals are correctly set as a pair based on the result (
O). As a result, if it is normal, an address map of the installed dependent station is created), and if it is abnormal, a message to that effect is displayed (θ) After 0, each dependent station is created according to the address map. Sequential communication (■) 0 By doing so, unnecessary polling and selecting operations for uninstalled dependent stations can be avoided, so that the communication cycle can be shortened. Also,
This operation is performed automatically every time the power is turned on, so
This has the advantage that no complicated work is required even when increasing or increasing the number of stages.

Note 1: When creating an atmap as described above, if you set the number of slave stations that can communicate with each other in advance and compare that number with the number of valid addresses in the address map, you can easily find the slave stations that should be registered. You can avoid the mistake of dropping it.

[Brief explanation of the drawing]

Figure 1 shows a data communication system according to the present invention.
- A block diagram showing an overview, FIG. 2 is a block diagram showing the detailed structure of the dependent station in FIG. 1, and FIG.
[FIG. 4 is a block diagram showing the detailed configuration of the I department (control unit), FIG. 4 is an information configuration diagram showing the seven formats of transmission information, and FIG. 5 is a 70-chart for explaining the operation according to the present invention. Code explanation 1...Subordinate station, 111 F 112, 113
......Sending terminal, 121 e 122 e 12
3... Receiving terminal, 2... Control station (roll unit), 11... Waveform shaping s, 1
2... Read timing pulse generator, 13
... Address verification section, 14 ... Shift register, 15 ... Command discrimination section, 16 ...
... Verification circuit, 17 ... Digital output circuit, 18 ... Input section, 19 ... Parallel/serial conversion section, 21 ... Power supply, 22... Arithmetic control unit (CPU), 23... RAM or ROM, 24... Input/output circuit, 25...
・External equipment, 26. Dll... Driver, 2
7...Song data reading circuit, T19T2...
Terminal, SWl @ SW2...Switch. Agent Patent Attorney Akio Namiki Agent Patent Attorney Kiyoshi Matsuzaki lJ l Figure 2 Figure 3 Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] 1) Transmission of multiple pairs of a control station, a transmitting terminal, and a receiving terminal with the same address. In a data communication system in which receiving terminals are connected in parallel to each other via a common line and data is repeatedly exchanged at a predetermined period between the control station and individual transmitting and receiving terminals using a polling and selecting method, the control station scans each terminal sequentially when the power is turned on, creates an address map for the installed terminal depending on whether or not predetermined data is returned from the corresponding terminal, and conducts subsequent communications based on this address map. A data communication system characterized in that unnecessary access to uninstalled terminals is avoided by doing so. 2. The data communication system according to claim 1, wherein it is determined whether or not the sending and receiving terminals are installed bare based on the address map. 3) In the data communication system according to claim 1 or 2, the number of subordinate stations that can communicate is stored in advance in the control station, and the number of stations and the number of subordinate stations are registered in the address map. A data communication system characterized by checking for omissions in registration in an address map by comparing the number of valid stations.