Abstract: Preventing signals from undesirably entering and enabling interactive communication. Signals from a main line or branch line are received by receiving circuits. Signal detecting circuits detect signals, and then transmit the detected signals (detection B and detection A) to a first-arrival judging circuit. The first-arrival judging circuit determines which signal is the first arrival between the signals from the detecting circuits, and then allows one of transmitting circuits to output a signal. Accordingly, only one of the transmitting circuits generates signals, preventing signals of the other transmitting circuit from entering and enabling interactive communication.

Abstract: A communication data processor. Data received from a communication channel is stored in a data area. A list area corresponding to the data area in which the communication data has been stored is deleted from a vacant list management area and then added to a logical check list management area. A list area corresponding to a data area logically checked by a lower layer logical check section is deleted from the logical check list management area and then added to a higher layer protocol classification list management area. A list area corresponding to a data area classified by a higher layer protocol classification section is deleted from the higher layer protocol classification list management area and then added to the vacant list management area. When data relating to a protocol having an OSI model is to be processed, it is not required to perform the transfer of real data in a data storage.

Abstract: A communication control section is provided with a plurality of receiving channels (RXDA1 and RXDA2). An address separated by an address separating section constituting the RXDA1 is compared with a reference address denoting a token, and if the separated address corresponds thereto, an interruption is requested by an interruption processing section. An address separated by an address separating section constituting the RXDA2 is compared with a reference address denoting the station number of that particular station, and if the separated address corresponds thereto, the interruption is similarly requested. When the interruption has been requested, the processing of a CPU transfers from the processing of a main routine by a main routine processing section to an interruption processing by an interruption processing section.

Abstract: A shared memory system and an arbitrating method and system. When the processing is distributed over a plurality of CPUs (e.g., CPUA and CPUB) and if it is desired that a shared memory is used to transfer data between the CPUs, a clock CKG indicating the CPUA access timing clock is generated. A gate signal G indicating the access right to the shared memory is generated in synchronism with the clock CKG. When either of the CPUs requests the access to the shared memory, it makes the corresponding chip select signal CSA.sup.- or CSB.sup.- L-level. The access right is always directed to the CPUA and switched to the CPUB in response to the access demand from the CPUB. After one access has completed, the CPUB makes CSB.sup.- H-level. Thus, the access right is switched to the CPUA. After one access has terminated, the CPUA makes CSA.sup.- H-level. If the CPUB requests the access at this time, the access right is switched to the CPUB.

Abstract: A gateway as one example of a mutual connecting appraratus between networks virtually provides an address of a mini manufacturing automation protocol (miniMAP) device to a mechatronics network (ME-NET) device in plural devices forming a network so that the miniMAP device uniquely identifies the ME-NET device. These plural devices connected to respective networks can mutually transmit and receive data in a network environment in which the ME-NET device is connected to the miniMAP device or another ME-NET device. Conversely, an address of the ME-NET device may be virtually provided to the miniMAP device so that the ME-NET device uniquely identifies the miniMAP device. Further, for example, the plural devices may be constructed by ME-NET devices. In this case, one ME-NET device uniquely identifies another ME-NET device in the plural ME-NET devices by virtually providing a station address unused in this one ME-NET device to this another ME-NET device.

Abstract: A communication network is comprised of several stations that constitute a logical ring to transmit and receive information. The logical ring is established and maintained by a token passing process and a solicit process. The token represents the right to transmit information between the stations in the logical ring. The solicit process solicits stations that are not in the logical ring. The stations in the network include at least one particular station. Each of the stations as well as the particular station include soliciting capability for carrying out the solicit process when holding a token. In addition, each station except for the particular station also includes first solicit repeat capability for repeating the solicit process at most a predetermined number of times when no frame arrives from other stations in the network, and the function of moving to an idle state when no frames arrives from other stations after the solicit process is repeated.