JPH0254647A - Method and apparatus for data communication - Google Patents

Abstract

PURPOSE:To attain the data transmission at a fixed period by sending an optional data from a slave equipment at a transmission area of prescribed number of consecutive fields and providing number of consecution of fields by number of slave equipments so as to apply formatting. CONSTITUTION:One field is formed by the 1st and 2nd transmission areas S1, S2 from slave equipments, the 1st and 2nd transmission areas M1, M2 from a master equipment, and a blank B. As to the 2nd transmission area S2 from slave equipments, the transmission of an optional data is finished from the slave equipment by prescribed number (m) of fields and the n-set of fields by the number of slave equipments are provided through a blank field to form a format of nX(m+1)=25 fields and the format is repeated. Thus, each data is sent at a fixed period of number of slave equipments (n) X prescribed number (m+1) and the data processing is facilitated.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a data communication method and apparatus suitable for use when performing bidirectional communication between a VTR as a master device and a slave device such as a video camera or an editing device. . [Summary of the Invention] The present invention relates to a data communication method and device, and relates to a data communication method and device, and the present invention relates to a data communication method and device. The slave device is provided with means for detecting boundaries between a series of a predetermined number of fields and a means for determining data collision. By ensuring good data transmission and determining data collision based on the mismatch between the transmitted data and the signal on the communication path, it is possible to always make a good collision determination. [Prior Art] For example, it has been considered to connect a video camera, a timer/tuner unit, an editing device, etc. to a VTR to perform various functions. In that case, it is necessary to communicate data between devices,
As a method for this purpose, the applicant of the present application first proposed a method for communicating data between a large number of devices using a small number of transmission areas (see Japanese Patent Laid-Open No. 158237/1983). That is, in FIG. 14, the figure shows the configuration of the transmission area of one field, and in the figure, the first,
A second transmission area (St) (S2) is provided, followed by a first and second transmission area (M+) from the master device.
(M2) is provided. These transmission areas (St)
~(M2) each has a data capacity of, for example, 2 words (32 bits), and the total of 4 areas is 128 bits. Therefore, for example, each bit can be synchronized with the horizontal scanning of the video signal, and the data field can be synchronized with the field of the video signal by leaving areas other than the transmission area blank. Further, for this field, the slave device selects one of the transmission areas (31) and (32) to transmit data. In this case, if one transmission area is being used for transmission from another slave device, the other transmission area can be selected for transmission, and only when both transmission areas are being used can either By simply waiting until the end of the transmission, data can always be transmitted smoothly. [Problem to be Solved by the Invention] However, for example, when devices are connected using a VTR as a master device as described above, it is difficult to check the operating status of auto functions such as autofocus from a video camera, timer, etc.
Data representing the status of the equipment, such as reception channel information from the tuner unit, must be transmitted periodically. In this case, with the above communication method, there is a very high possibility that data will be transmitted from three or more slave devices at the same time, and if the data transmission is made to wait for this reason, the data transmission cycle will fluctuate. If the period fluctuates in this way, data processing becomes complicated, which may cause problems, especially when interpolating data dropouts. This application was filed in view of these points. [Means for Solving the Problems] A first means for solving the problems according to the present invention is a data communication method that performs bidirectional communication between a master device and one or more slave devices. At least the transmission area (S2) from the slave device for one communication path
A field having a field is provided at a predetermined period, and
Transmission of arbitrary data from the slave device is completed with the predetermined number (m) of the fields, and the format is such that the predetermined number of fields are small (at least as many as the number (n) of the slave devices). A second means is a data communication method in which the slave device is provided with a counter means (9) corresponding to the number of fields in the format, in contrast to the data communication method of the first means. The data is transmitted according to the count value (microcomputer (3)) and the boundary of the series of the predetermined number of fields is detected (blank discrimination circuit (6)) and the counter means A means for correcting the count value of the output bit check circuit (output bit check circuit
)) for arbitrarily changing the count value of the counter means. The third means is that in the second means, the collision determination (output bit check circuit (8)) is performed by detecting the signal on the communication path and detecting that this detection signal does not match the transmitted data. Become (EX or (81)
) is a data communication device. [Operation] According to this, each data is transmitted by the first means at a fixed period of the number of slave devices x a predetermined number of fields, and the data can be easily processed. Also the second
By means of the above means, it is possible to perform good data communication using a boundary detection signal of a series of a predetermined number of fields and a data collision determination signal. Furthermore, by the third means, it is possible to always accurately determine data collision based on the mismatch between the transmitted data and the signal on the communication path. [Example] FIG. 1 shows the structure of the format. In the figure, the first and second transmission areas (St), (s
z>, the first and second transmission areas from the master device (M
(1) One field is formed by (M2) and blank (B), and this field is repeated in synchronization with, for example, a field of a video signal. In the figure, continuous fields are arranged vertically. For example, the second transmission area (S
Regarding 2), the transmission of arbitrary data from the slave device is completed in a predetermined number m (for example, 4) of fields, and a series of this predetermined number of fields is a blank field indicating the boundary of the series. The number n (for example, 5) of slave devices is provided via n x (m+1)
-25 field formant, and this formant is further repeated. As a result, each data is transmitted at a fixed cycle of the number of slave devices (n) x a predetermined number of fields (m + l),
Ability to easily process data. Further, FIG. 2 shows the configuration of a communication device provided in the slave device. In the figure, (1) is a data bus that connects a master device and other slave devices. The signal of this data bus (1) is supplied to the synchronization separation circuit (2), and, for example, the above-mentioned fields and each transmission area (S, ) to
A synchronizing signal corresponding to (M2) is separated and supplied to a microcomputer (3) that performs control. First, the computer (3) transmits the transmission area from the master device (
A signal corresponding to Ml) (M2) is sent to the data receiving circuit (4
), and the signal on the data bus (1) during this time is taken out and supplied to the data processing device (5) in the slave device. Furthermore, the computer (3) sends a second message from the slave device.
A signal corresponding to the transmission area (S2) is supplied to the blank detection circuit (6), and when the transmission area (S2> becomes blank), a detection signal is supplied to the computer (3). The boundary between the predetermined number of fields mentioned above is detected, and the data transmission circuit (7) is controlled in accordance with this detection, and the data processing device (5)
A signal from is sent to the data bus (1). Furthermore, the transmission data from the data transmission circuit (7) and the signal on the data bus (1) are supplied to the output bit check circuit (8), and when they do not match, it is determined that there is a data collision, and this determination signal is sent to the computer. (3), and it is determined whether to stop transmitting data, which will be described later. In addition (9
) indicates a counter means in the computer (3), and this counter means

[9] is counted, for example, from 0 to 24 in synchronization with the field synchronization signal from the above-mentioned separation circuit (2) according to the software described later. Furthermore, all or part of the above-mentioned apparatus may be provided as software in the computer (3). 3 to 11 are explanations of the operation of this apparatus, and FIG. 3 first shows the output judgment main routine. In the figure, at step [31], the above-mentioned counter means (4)
The count value (timing number - TN) is determined, and when TN is 0.5.10.15, the process proceeds to the vacancy confirmation routine [40]. Also, TN is 1-4.6-9
．． 11-14. When the time is from 16 to 19, the routine proceeds to time adjustment routine [60]. Further, when the TN is 20, the process proceeds to the output preparation routine [80], and the TN is 21 to 24.
If so, the process proceeds to the output check routine [:100]. Next, FIG. 4 shows a vacant space confirmation routine [40]. In the figure, in step [41], it is determined whether the transmission area (S2) at that time is blank. Here, the judgment step is assumed to be upward when the answer is yes, and downward when the answer is no. Therefore, when the answer is YES, the value of the field number (=FN) is set to 0 in step [42], and the value of TN is incremented in step [43]. If the answer is NO in step [41], the value of FN is incremented in step [44], and it is determined in step [45] whether the value of FN is 5 or more. If YES, the value of FN is set to 5 in step [46]. Also, if step [45] is NO, step [47]
] After it is determined whether the value of TN is 0 or not, step [48
], the value of TN is set to TN+FN+1. If YES in step [47], the value of TN is left unchanged, and if NO, the value of TN is set to TN-5. With this, when the value of TN is a multiple of 5, the transmission area (
The value of TN is modified so that S2) becomes blank. That is, in FIG. 5, for example, if the transmission area (S2) is blank when the value of TN is 5, the FNO value is set to 0 and the value of TN is incremented. On the other hand, if there is a transmission from another slave device (indicated by hatching) at a position where the TN value is 7 to 10, the transmission area (S,) is no longer blank when the TNO value is IO, and this When the value of FN is incremented, the value of TNO becomes T N + F N + l, and from this value T
N=5, for example 10. As a result, the next time the value of TN becomes a multiple of 5, the transmission area (S
2) is modified to be blank. Next, FIG. 6 shows a time adjustment routine [60]. In the figure, in step [61] it is determined whether the transmission area (S2) at that time is blank. If the answer is yes, the FN value becomes 0 in step [62].
It is determined whether or not. Furthermore, if the answer is YES in step [62], the value of TN is incremented in step [63]. If the answer is NO in step [62], the value of TN is set to TN-FN in step [64], and the value of FN is set to 0 in step [65]. Also step [6
1], the FN value is incremented in step [66], and the TNO value is incremented in step [67]. As a result, when the value of TN is a multiple of 5, the TNO value is corrected so that it becomes a blank field at the boundary of a series of the above-mentioned predetermined number of fields. In other words, in FIG. 7, if there is a transmission from the pond slave device in the transmission area (S,) when the TN value at the start of operation is O (the FN value is also 0), the above-mentioned vacancy check will be performed. The FNO value is set to 1 and the TNO value is set to 2 by routine [40]. Furthermore, even if the TN value is 2, if there is a transmission from another slave device, the FNO value is set to 2 and the TN value is set to 3 in steps [66] (67). When the transmission area (S2) becomes blank, step (
64) The value of TN is set to 1 and the value of FN is set to 0 at [:65). Furthermore, when there is a transmission from another slave device with a TH value of 1 to 4, FN is generated. The value of TN is incremented sequentially, and when the value of TN is 5, it is matched with a blank field at the boundary of a series of a predetermined number of fields. Furthermore, FIG. 8 shows the output preparation routine [80]. In FIG. 1, first, in step [81], the value of FN is set to 0, and then in step [82], the transmission area (S
It is determined whether or not 2) is blank. When the answer is YES, the TNO value is incremented in step [83], and in step [84], the first output data (2 words) is set in the data transmission circuit (7). If the answer is NO in step [82], the output data is cleared in step [85]. As a result, when the value of TN is 20, the transmission area (S2
) is blank, the output data is set so that data is sent from the next field. That is, in FIG. 9, for example, if the transmission area (S2) becomes blank when the value of TN is 20, the value of FN is set to 0 and TN
The value of is incremented and output data ■ is set. Further, when the next TH value is 21 and there is a transmission from another slave device in the transmission area (S2), the TN value is returned to 20 in the output check routine [100] to be described later. At this time, if transmission from another slave device continues, the value of FN remains 0, the value of TN remains 20, and the output data is cleared. Furthermore, when the transmission from another slave device ends and the transmission area (S2) becomes blank, the value of TN is incremented again.
Output data ■ is set. FIG. 10 shows the output check routine (100). In the figure, first, in step [11], the value of FN is incremented, and then in step [12], it is determined whether or not the bit check has detected an error. When the answer is YES, the value of TN is set to TN-FN in step [13], and the output data is cleared in step [14]. If the answer is NO in step [12], the value of TN is incremented in step [15], and the value of TN is further determined in step [16]. When the value of TN is 22, the value of TN is incremented in step [15].
], the output data ■ is set in the data transmitting circuit (7), when the value of TH is 23, the output data ■ is set in step [18], and when the value of TN is 24, the output data ■ is set in the data transmission circuit (7).
], the output data ■ is set, and when the value of TN is 25, the output data is cleared in step [20], and then the value of TN is set to 0 in step [21]. As a result, output data ■ to ■ are transmitted when the TN value is 21 to 24, and data transmission is stopped when a needle strike is detected on the data bus (1), and the next Transmission is performed again in a series of a predetermined number of fields.In other words, in FIG. 11, for example, when the value of TN is 20, the above-mentioned output preparation routine [80] outputs it to the field where the value of TN is 21. Data ■ is set and if a data collision is determined in this field, transmission is stopped.Then, next is the transmission area (S2
) becomes blank, the output data ■ is set again in the field with the TNO value of 21, and if there is no data collision, the output data ■ to ■ are transmitted in the fields with the TH value of 21 to 24. As a result, it is possible to perform good data transmission using the boundary detection signal of a series of a predetermined number of fields and the data collision determination signal. In other words, by specifying that periodic data transmission from each slave device in the above device is always performed, the position of the field to be transmitted after all slave devices have started transmitting data in the above operation. are fixed to each other, and transmission is always performed at a constant cycle. Furthermore, FIG. 12 is a time chart for determining a data collision. When a signal such as the one shown in FIG. When the signal on the data bus (1) is transmitted, the signal on the data bus (1) becomes an OR signal of both signals as shown in FIG. Therefore, when the signals of B and C become inconsistent, it is determined that there is a data collision and the transmission of the own data after that bit is stopped (D in the same figure). ) will be sent without delay. The specific configuration for realizing this operation is as follows:
For example, as shown in FIG.
71) to the data bus (1), the transmitted data and the signal on the data bus (1) are supplied to the intrusive (EX) OR circuit (81), and this output is sent to the computer (3). The flip-flop formed within (
31). This can be realized by supplying this Q output to an AND circuit (71). As a result, data collision can always be accurately determined based on the mismatch between the transmitted data and the signal on the communication path. Note that in the above-described method and device, by specifying that transmission from the slave device is always performed, it is also possible to determine whether the device is connected or not, or whether an accident has occurred. Furthermore, the above-mentioned predetermined number m and the number n of slave devices can be arbitrarily determined depending on the basic design of the system. Furthermore, in the method described above, the first transmission area (Sl) from the slave devices can be used for temporary data communication from each slave device. [Effects of the Invention] According to the present invention, each data is transmitted by the first means at a fixed period of the number of slave devices x a predetermined number of fields, and the data can be easily processed. Furthermore, the second means allows for good data transmission using the boundary detection signal of a series of a predetermined number of fields and the data collision determination signal. Furthermore, by means of the third means, data collisions can always be accurately determined based on the mismatch between the transmitted data and the signal on the communication path.

[Brief explanation of the drawing]

FIG. 1 is a diagram for detailed explanation of the present invention, FIG. 2 is a block diagram of the apparatus of the present invention, FIGS. 3 to 11 are diagrams for explanation thereof, and FIGS. 12 and 13 are FIG. 14, an explanatory diagram of determining data collision, is a diagram for explaining the conventional technique. (1) is a data bus, (2) is a synchronization separation circuit, (3) is a microcomputer, (4) is a data receiving circuit, (5)
) is a data processing device, (6) is a blank discrimination circuit, (7
) is a data transmission circuit, (8) is an output bit check circuit, and (9) is a counter means. Agent Paige Ito
Hide Matsukuma Seibutsu Wrinkle Field CB) Fig. 2・O", B Fig. 1 Output Judgment Meishiro Presi Fig. 3-FN HH. (Is) I-@. CB) Wolf 1 0 3 Wolf 4 HH (B) Sophistry, Sun/Moon Chart Figure 5 Figure 8-I”N Ho Ho BI Ho (BI Q BI Information 10th. i%) Mouth 1 Q Part 0 Ro OF-@. (B) Miyata June 1 Otsu Figure 8 Figure 6 FN Kuko 1 0 Ko 2 1'7'iTl. 2 pieces 1 wolfberry 3 0 ヰ(B) Yoshitoro and the Sun and Moon Figure 7 Book of wolfberry 1 bite 1 bite 1 bite 1 note 8Fl12 Figure 11

Claims (1)

[Claims] 1. A data communication method for performing bidirectional communication between a master device and one or more slave devices, wherein a single communication path has at least a transmission area from the slave device. The field is provided at a predetermined period, the transmission of any data from the slave device is completed in a predetermined number of the fields, and the series of the predetermined number of fields is provided at least as many times as there are the slave devices. A data communication method in which the same format is repeated. 2. With respect to the data communication method according to claim 1, the slave device is provided with a counter means corresponding to the number of fields in the format, and the data is transmitted according to the count value. and means for detecting a boundary between a series of the predetermined number of fields and correcting the count value of the counter means, and determining a collision between data transmission from another slave device when transmitting the data. and means for arbitrarily changing the count value of the counter means. 3. The data communication device according to claim 2, wherein the collision is determined by detecting a signal on the communication path and detecting a discrepancy between the detected signal and the transmitted data.