Abstract: When a CPU core 53 of a node detects change of data which comes into the node from a load 60 connected thereto on the input side, and thereby the CPU core 53 and a transmission control circuit 52 wake up, the node transmits a frame for waking-up to a transmission line 4. However, when the node receives a frame for waking-up from another node via the transmission line 4 and thereby wakes up, the node does not transmit a frame for waking-up. Thus, an increase in traffic at the time of waking up is reduced and data transmission in a normal operation mode is started soon, so that the speed of data transmission is increased.

Abstract: Basic nodes each having a communication control circuit and a CPU and I/O nodes each having a communication control circuit are interconnected via a bus. Each of the communication control circuits makes the bus active when transmitting a frame therefrom, and on judging that the bus is not active when receiving the frame, suspends the frame transmission and enters a transmission inhibited state. The basic nodes periodically transmit a frame, and when this frame is received, each I/O node cancels its transmission inhibited state and thus is restored to the state in which the frame transmission therefrom can be initiated.

Abstract: A multiplex transmission apparatus, having a communication control circuit for carrying out transmit-receive control of a frame of data transmitted through a bus, and an output port for outputting data in frame received by the communication control circuit. The multiplex transmission apparatus is operated by a power supply voltage supplied from a power supply circuit to perform data communication with another multiplex transmission apparatus via a bus. First and second low voltage detection circuits, when detecting preset voltage values V.sub.L and V.sub.R of a power supply voltage, reset the communication control circuit and the output port. This multiplex transmission apparatus keeps the output of the output port in a normal condition despite relatively small variations in the power supply voltage (i,e., where V.sub.L .gtoreq.power supply voltage>V.sub.R).

Abstract: A multiplex transmission apparatus includes a communication control circuit, which monitors data output from an output port and which changes the state of the output port to a predetermined specific state when at least part of the monitored data fails to show a predetermined periodic change with respect to corresponding data previously output, and is operated by a power supply voltage applied thereto from a power circuit to carry out data communications with other multiplex transmission apparatuses. A communication IC maintains the operating state of or resets the output port and the communication control circuit of the multiplex transmission apparatus in accordance with the result of detection by a low-voltage detecting circuit, and a gate circuit inhibits the output port from being changed to the specific state by a timer IC when low voltage is detected or during sleep mode.

Abstract: A multiplex transmission system includes a plurality of multiplex nodes interconnected by a common multiplex transmission line. Data frames are transmitted among the multiplex nodes through the multiplex transmission line. A data frame transmitted from a sending multiplex node includes a data area which is divided into subdivided areas in accordance with data transmitted therefrom and data transmitted from receiving multiplex nodes which send data in response to a send request, in accordance with the number of data pieces or the number of bits, and the receiving nodes send data to respective subdivided areas in a predetermined order, to thereby carry out a data transmission. Accordingly, the sending multiplex node can simultaneously collect data from the receiving multiplex nodes which are functionally subordinate. When any of the receiving multiplex nodes fails to return an ACK signal, the sending multiplex node retransmits the data frame.

Abstract: When a message is transmitted, frame by frame, from any one (10) of a plurality of multiplex nodes to a common multiplex bus (MB) to which the multiplex nodes are connected, each of the multiplex nodes (20 and 30) determines that transmission of a frame therefrom is allowed when it detects a transmission permission signal (b, b') added to the frame after detection of and idle state of the multiplex bus, and starts transmitting a message data frame. This makes it possible to properly implement priority-based control according to the priority levels of the data frames irrespectively of variations in the reference clocks of the multiplex nodes. Further, receiving multiplex nodes perform frame synchronization at the rise of a special code (a) of a start code (SOM) of a message data frame, and then perform re-synchronization at the rise of a special bit pattern (b") which includes a passive bit and a dominant bit.

Abstract: A multiplex transmission system of this invention includes a plurality of multiplex nodes interconnected by a common multiplex transmission line. A frame of data is transmitted among the multiplex nodes through the multiplex transmission line. When a data frame transmitted from an air conditioner switch multiplex node (subnode) is received, an air conditioner unit multiplex node (main node), which is predetermined as a destination node, detects the contents of each data from an ID-a of the received data, performs a calculation on SOM to DATA 4 received, generates collation data (CRC) in accordance with the result of the calculation and transmits same. The subnode generates collation data (CRC), which is an error check code, through a calculation on the transmitted SOM to DATA 4, and compares the thus-generated CRC with the CRC received from the main node, to determine whether or not the data transmission was properly carried out.

Abstract: A multiplex transmission system of this invention includes a plurality of multiplex nodes interconnected by a common multiplex transmission line. A plurality of groups of different combinations of the multiplex nodes are predetermined, and a frame of data is transmitted among the multiplex nodes through the multiplex transmission line. The data frame includes a group specifying area specifying a group of nodes from which an acknowledge signal is to be returned. When a data frame transmitted from a sending node is received, each multiplex node determines whether or not it belongs to the group specified by bits in the group specifying area of the transmitted frame. When the data frame is properly received, only those multiplex nodes which belong to the specified group return the acknowledge signals to an acknowledge signal area in the data frame in accordance with the bits in the group specifying area, whereby the transmission efficiency is improved.

Abstract: The data storing system according to the present invention is used for a communication control circuit. The communication control circuit is equipped with a communication sequencer, which takes in a message to be transmitted to a multiplex bus, an ID table which registers data IDs of messages necessary for the station, and the first and second memory circuits which have memory areas keyed to the data IDs. When the communication sequencer takes in a message, it determines whether its data ID exists in the ID table. If the data ID exists and the frequency of occurrence is high, then data following the data ID is temporarily stored in a memory area keyed to a data ID of the first memory circuit. If the data ID exists and the frequency of occurrence is low, then the data following the data ID is temporarily stored in a memory area of the second memory circuit.

Abstract: A multiplex transmission system according to this invention includes a plurality of multiplex nodes connected to one another via a common multiplex bus, for effecting data transfer between the nodes. When reception nodes correctly receive data transmitted from one of the nodes for each frame, each of the reception nodes returns an ACK signal to the multiplex bus, registers all of the nodes connected to the multiplex bus into the ACK table in response to the ACK signal, and effects the ACK management. In this case, for example, if a door FR multiplex node causes an interruption to transmit a frame while an air-conditioning unit multiplex node is retransmitting a frame, the air-conditioning unit multiplex node effects the ACK management without regarding the ACK signal for the interruption frame as an object of the updating logic of its own ACK table.

Abstract: A receipt acknowledgement method which is applied to a multiplex transmission system provided with a plurality of multiple nodes (11 to 17) connected to one another through a multiplex bus (18), and is capable of conducting efficient data transmission, and in which a transmitting multiplex node (13) sends out a frame and, after entry into an ACK signal area of the frame, sends out a delimiter sign consisting of passive and active two bits with a four-bit interval, thereby dividing the acknowledgement signal area. The receiving multiplex nodes (11, 12, 14 to 17) are synchronized according to an active bit sent out from the transmitting multiplex node (13), and returns ACK signals to the ACK signal area in the predetermined order when data transfer on the transmission request frame has been normally performed, whereby data transmission can be conducted at high speed with improved efficiency.

Abstract: A transmission failure diagnosis apparatus for use in a multiplex transmission system which sends and receives data by time division communication among a plurality of nodes connected by a common transmission path. This transmission failure diagnosis apparatus comprises a reception circuit, connected in the transmission path, for receiving a transmission signal on the transmission path, an amplitude detection circuit for detecting the signal amplitude of a transmission signal received by this reception circuit, and a judgment circuit for judging failures in the system on the basis of the amplitude of the transmission signal detected by the amplitude detection circuit.