JPS60230743A - Bus connecting system - Google Patents

Abstract

PURPOSE:To prevent the ineffective processing of a noise generated in an information bus being in a non-communication state, by making a data from the information bus receivable, only when a bus effective signal from a signal bus provided on the outside of the information bus has been received. CONSTITUTION:A main device Me and plural sub-devices SE1-SEn send and receive a data through an information bus IB, but at the time of non-communication, only a receiving part R of a high impedance is connected to the bus IB, and in case of transmitting the data, a transmitting part D is connected to the bus IB. A signal bus SB for transmitting a bus effective signal is provided independently from the bus IB. In case of starting the communication, a control part CTL' monitors in advance the bus SB through a signal receiving part SR, confirms that the bus effective signal is not sent out of any device, sends the bus effective signal to the bus SB through a signal transmitting part SD, and thereafter, connects the transmitting part D to the bus IB, and sends the data. Each device receives the bus effective signal through the receiving part SR, and thereafter, the control part CTL' processes information received through the receiving part R from the bus IB.

Description

DETAILED DESCRIPTION OF THE INVENTION +al Technical Field of the Invention The present invention relates to a bus-type communication system, and particularly to a bus connection method that can improve the efficiency and reliability of communication via a bus.

(b) Background of the technology One main device and a plurality of slave devices are connected, for example, by a loop bus, and under the control of the main device, the main device and one or more slave devices are connected. Communication systems that transmit and receive data via buses are widely used.

(C1 Prior Art and Problems FIG. 1 is a diagram showing an example of a conventional communication system of this type. In FIG. 1, one main device ME and n slave devices SEl to SEn exchange data. Information bus I to transmit
They are connected in a loop by B. Each main device ME and slave devices SEI to SEn includes a low output impedance transmitting section that transmits data to the information bus IB, a high input impedance receiving section R that receives data arriving from the information bus IB, and a transmitting section. and a control unit CTL that controls the receiver R and performs data analysis processing. The main device ME and each slave fit in a non-communication state
S E 1 to SEn connect only the receiving section R to the information bus IB.
The transmitting section is connected to the information bus IB only when data is to be transmitted. The control unit CTL in the main device ME that starts communication connects the transmitting unit to the information bus IB, and then
The addresses assigned to each of the axis devices SE1 to SEn are sequentially sent to the information bus IB via the transmitter. Each axis device SEI to SEn receives the address transmitted from the main device ME via the information bus IB via the receiving unit R, analyzes it by the control unit CTL, and matches the address assigned to the own device. The slave device SEi (where i is any one of 1 to n) connects its transmitting section to the information bus IB, and sends and receives data to and from the in-vehicle WME via the information bus IB. Note that the main device ME can also transmit data to a plurality of predetermined slave devices SEi at the same time by sending an address commonly assigned to the plurality of predetermined slave devices SEi.

As is clear from the above explanation, in a conventional communication system, the main device ME and the slave device S are in a non-communication state.
Since EI to SEn connect only the receiving section R with high input impedance to the information bus IB, the noise voltage generated in the information bus IB in a non-communication state is transmitted to the main device ME and each axis device SE1 to SE1 without attenuation. There is a high possibility that it will be transmitted to SEn and cause it to perform invalidation processing.

(d) Object of the Invention An object of the present invention is to eliminate the drawbacks of conventional communication systems as described above, and to realize means that can prevent noise from being ineffectively processed in a non-communication state.

fe) Structure of the invention This object is to provide a communication system in which a main device and a plurality of slave devices are connected by a single bus, and the main device and/or the plurality of slave devices transmit data via the bus. In,
A signal bus is provided that connects all the master devices and slave devices independently of the bus, and the master device or the slave device sends data to the bus after sending a bus enable signal to the signal bus, and This is accomplished by enabling the device and slave device to receive data transmitted via the bus after receiving the bus valid signal from the signal bus.

That is, according to the present invention, the main device and each slave device no longer receive and process invalid data such as noise that arrives from the bus in a non-communicating state, improving the efficiency and reliability of the communication system.

(fl　Embodiments of the invention An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing a bus connection system according to an embodiment of the present invention. Note that the same reference numerals indicate the same objects throughout the figures. In FIG. 2, a signal bus S transmits a bus valid signal indicating that the information bus IB transmits valid data.
B is provided in addition to the information bus IB, and the main device ME
Each axis device SEI to SEn is connected to a signal bus SB via a signal transmitter SD and a signal receiver SR. In addition, each vehicle NME and slave devices SEI to SEn
The control unit CTL' does not process all data received from the information bus IB via each receiving unit R in a state in which the hash valid signal is not received from the signal bus SB. In FIG. 2, a control unit CTL' in the main device ME that starts communication
monitors the signal bus SB in advance via the signal receiving section SR,
After confirming that none of the slave devices SEl to SEn is sending out a lotus valid signal on the signal bus SB, it starts sending a lotus valid signal to the signal bus SB via the signal transmitter SD, and at the same time, the transmitter Connect to the information lotus IB. In each axis device SEI to SEn, the control unit CTL'
When the hash valid signal transmitted from the signal bus SB is received via the signal receiving section SR, it is transmitted from the information bus IB to the receiving section R.
enables the processing of data received via. In this state, when the main device ME sends the address assigned to the slave device SEi to the information bus IB via the transmitter, each axis device SE1 to SEn transmits the address from the main device ME via the information bus IB. The slave device SEi receives the address given by the receiver R via the receiver R, analyzes it by the controller CTL, and if the address matches the address given to its own device, the slave device SEi connects the transmitter to the information bus IB, Main device ME via
Receive data transmitted from. After transmitting the data, the main device ME sends a signal S via the signal transmitter SD.
Stop the lotus valid signal being sent to B. Note that the slave device SE
When i transmits data to the earth filling WME, the control unit CTL' of the slave device SEi starts sending a bus valid signal to the signal bus SB via the signal transmission unit SD, and
and the control units CTL' of the other slave devices SEl to SEn are enabled to process data. Control unit C of main device ME
TL' monitors the bus valid signal transmitted on the signal bus SB via the signal receiving section SR, and when it confirms that the lotus valid signal being sent has stopped, the slave device S specified by the address
It is determined that communication with Et has ended, and the next slave device 5Ej (
j sends a bus valid signal onto the signal bus SB in order to start communication with any one of 1 to n). Thereafter, data is transmitted and received with the target slave device SEj through the same process as described above.

As is clear from the above description, according to this embodiment, the control unit CTL of the main device ME and each axis device SEI to SEn
' does not process the data transmitted from the receiver R unless a bus valid signal arrives from the signal bus SB.

Therefore, there is no possibility that noise arriving from the information bus IB in a non-communication state will be invalidated by each control unit CTL.
After confirming that there is no bus valid signal on the signal bus SB, SEn starts the data transmission process that starts with sending the bus valid signal, so double transmission of data on the information bus IB is ensured. Prevented.

Note that FIG. 2 is only one embodiment of the present invention, and for example, the configuration of the main device ME and each axis device SEI to SEn,
Furthermore, the shape of the information bus IB is not limited to that shown in the drawings, and many other modifications may be considered, but the effects of the present invention will not change in any case.

(g+ Effects of the Invention As described above, according to the present invention, invalid processing of noise in a non-communication state is prevented, and the efficiency and reliability of the communication system are improved.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example of a conventional communication system, and FIG. 2 is a diagram showing an input connection method according to an embodiment of the present invention. In the figure, CTL and CTL' are control units, D is a transmission unit, IB is an information bus, ME is a main device, R is a reception unit, and SB
represents a signal bus, SD represents a signal transmitter, SEI to SEn represent slave devices, and SR represents a signal receiver. Figure 1 Figure 2

Claims (1)

[Claims] In a communication system in which a main device and a plurality of slave devices are connected by a single bus, and the main device and/or the plurality of slave devices transmit data via the bus, all of the slave devices are connected independently of the bus. A signal bus is provided for connecting the main device and the slave device, and the main device or the slave device sends data to the bus after sending a bus enable signal to the signal bus, and the main device and the slave device transmit data to the bus. A bus connection system characterized in that after receiving a valid signal from the signal bus, data transmitted via the bus can be received.