JPH0752885B2 - Home bus system transmission processing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a transmission processing method for a home bus system that controls electric devices in a home.

[Prior Art] In a home bus system for controlling electric devices in a home, as shown in FIG. 2, a plurality of transmitters / receivers A are connected to a signal line 1 of two lines, and the transmitters / receivers A are connected to each other. The signal is transmitted and received via the signal line 1. This home bus system adopts the CSMA / CD system standardized by IEEE, and the frame structure of the signal transmitted / received between the transmitters / receivers A is, as shown in FIG. 3 (a), the priority code PR (11 Bit), self address SA (11 bits), partner address DA
(11 bits), control code CC (11 bits), message length code BC (11 bits), data DATA (11 x maximum 256 bits), check code FCC (11 bits), dummy DMY (11
Bit equivalent time), ACK / NAK code ACK / NAK (11 bits)
Consists of. Here, signals except the data DATA and the dummy DMY is a 11-bit structure, as shown in FIG. 3 (b), a start bit of 1 bit, b ₀ ~b ₇ of 8-bit data, 1 bit Parity bit and 1 stop bit. Furthermore, in this home bus system, the AMI system shown in FIG. 3 (c) is adopted as a signal transmission system, and the pulse width is in the first half of 1 bit of 104 μsec.
"0" when there is a pulse signal of 52 μsec, "1" when there is no
In the case of "0", the polarity is inverted from that in the preceding case of "0".

In this type of home bus system, in consideration of the fact that the transmitter / receiver A starts transmission at the same time (contention occurs), the priority order of the transmitter / receiver A is set by the priority code PR, and the contention occurs. In the case of
Is to send. It should be noted that the transmitter / receiver A below the priority order has been transmitted from the transmitter / receiver A above the priority order
Transmission is made after 10 msec has elapsed. Here, the rest period of about 10 msec is provided to restore synchronization.

[Problems to be Solved by the Invention] By the way, in the transmitter / receiver A of the conventional home bus system of this type, since the start bit is detected at the rising edge, when the noise N is superimposed as shown in FIG. , The noise N is determined to be the start bit. However,
In the case of noise N, since there is no data, it is processed as a start bit error by determining whether or not the data within 3 msec after the detection of the start bit is detected. In short, in this conventional home bus system,
The noise N was judged as the normal signal S of the start bitler. Therefore, even when the transmitter / receiver A cannot transmit due to the noise N, it is possible to perform transmission after the quiescent period of about 10 msec has passed, as in the case of the above-described competition. However, in this case, for example, the superimposed noise N has periodicity, and when it is superimposed again after a lapse of about 13 msec as shown in FIG. There is a possibility that the inconvenience may occur in that the signal S of the home bus system cannot be transmitted and received continuously. Moreover, the noise N which is periodically generated is relatively large in the period of about 10 msec or more, and the above-mentioned problem is likely to occur in the transmission processing method at the time of noise superposition.

The present invention has been made in view of the above points, and an object of the present invention is to provide a signal transmission method for a home bus system that is less likely to be unable to transmit and receive signals due to periodic noise. is there.

[Means for Solving the Problems] In order to achieve the above object, the present invention determines noise when a pulse signal is not detected within a predetermined period from the rise detection of a pulse signal forming a start bit,
When it is determined that this is noise, it is characterized in that transmission is started from the transceiver within a time period shorter than the periodic noise generation period.

[Operation] As described above, the present invention detects noise and start bit error by detecting the presence or absence of a pulse signal within a predetermined period from the rise of the pulse signal forming the start bit and distinguishing between start bit and noise. Conflicts with other transceivers when it cannot be transmitted due to noise by making it possible to distinguish from a normal signal, and when the signal on the signal line is noise, the transceiver starts transmitting immediately after identification Without providing a pause as in the case of time, start transmitting immediately after identification and make the time from noise occurrence to transmission shorter than the cycle period of relatively frequent periodic noise. Thus, there is less risk that signal transmission / reception will become impossible due to periodic noise.

[Embodiment] In this embodiment, if the data b _{0 to} b ₇ are not detected within about 3 msec after the detection of the start bit ST, it is not judged as a start bit error, but the signal is noise N. If the transmission is impossible due to the noise N, the transmission processing different from the case where the normal signal S collides is performed. In other words, if the signal on the signal line 1 is noise N, it is not necessary to provide a pause period of about 10 msec for restoring synchronization.
As shown in the figure, after about 3 msec required for distinguishing the noise N from the start bit ST, the transceiver A
Is to start transmission immediately. In this way, if the transmission is impossible due to the noise N, it takes about 3 m to distinguish the noise N from the start bit ST.
The transmission can be performed immediately after the lapse of the time of sec, and the influence of the noise N becomes relatively small without being disabled due to the relatively large periodic noise N of about 10 msec or more.

EFFECTS OF THE INVENTION As described above, according to the present invention, when a pulse signal is not detected within a predetermined period from the detection of the rising edge of the pulse signal forming the start bit, it is determined to be noise. Since the transmitter / receiver starts transmission within a time shorter than the noise generation cycle, if the signal on the signal line is noise, the transmitter / receiver can immediately start transmission after identification, and transmission cannot be performed due to noise. If there is a conflict with other transceivers, there is no pause period, and transmission starts immediately after identification, and the time from noise occurrence to transmission occurs relatively frequently. It is possible to reduce the possibility that signal transmission / reception cannot be performed due to periodic noise by making the period shorter than the generation period of the periodic noise.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an operation explanatory diagram of an embodiment of the present invention, FIG. 2 is a system configuration diagram of a home bus system, and FIG. 3 is an explanatory diagram of signals transmitted and received by the home bus system, FIG. 4 is an explanatory diagram of a transmission processing method when a conventional home bus system cannot transmit due to noise, and FIG. 5 is an explanatory diagram of problems in the same. A is a transceiver, l is a signal line, S is a signal, and N is noise.

Claims (1)

[Claims] 1. A AMI system in which a plurality of transmitters / receivers are connected to a signal line, a priority order is set for these transmitters / receivers, and a start bit is provided as a leading bit between the respective transmitters / receivers via a signal line. When the transmitter and the receiver start transmitting at the same time, the signals are transmitted according to the priority order. In a home bus system that starts transmission after a lapse of a period, if a pulse signal is not detected within a predetermined period from the rising edge detection of the pulse signal that forms the start bit, it is determined to be noise. A transmission processing method for a home bus system, characterized in that transmission is started from a transmitter / receiver within a time period shorter than the generation cycle of.