Data communication system
View Patent ↗The present invention is provided with one main station and a plurality of substations. After transmitting data addressed to all substations, the main station transmits a message addressed to all substations to query whether reception was normal. When unable to receive data normally, the substations transmit a response message to the query message, but do not transmit a response message when data reception was normal. The time for confirming that transmission was normal or abnormal can be shortened by the main station transmitting data addressed to all substations only one time, and by the substations transmitting response messages only in the case of abnormal reception.
1. A data communication system comprising:
a main station;
plural substations, each of which is connected to said main station by a common transmission line;
a data transmitter which transmits data address to all of said plural substations, provided in said main station;
plural data receivers which receive said data, provided in said plural substations respectively;
a message transmitter which transmits a query message addressed to all of said plural substations after said data are transmitted, to inquire whether reception was normal, provided in said main station; and
plural response transmitters which transmit a carrier as a response message to said query message, only when said data could not be received normally, provided in said plural substations respectively;
wherein, whenever said main station receives a certain signal wave after transmitting said query message, said main station judges the signal wave said carrier transmitted from one or more of said plural substations and retransmits said data addressed to all of said plural substations and wherein when said main station detects no signal during a certain time period, the main station transmits the next transmission data.
2. The data communication system, according to claim 1 , wherein said main station receives said carrier within a prescribed period of time after the transmission of said query message.
3. The data communication system, according to claim 2 , wherein said prescribed period of time is the period until the time to start the next transmission of said data.
4. The data communication system, according to claim 2 , wherein said main station determines that all of said plural substations were able to receive said data normally, when said main station does not receive said carrier within said prescribed period of time.
5. The data communication system, according to claim 4 , wherein said main station effects the next data transmission when said carrier is not received within said prescribed period of time.
6. The data communication system, according to claim 2 , wherein said main station determines that any of said plural substations was unable to receive said data normally, when said main station receives said carrier within said prescribed of time.
7. The data communication system, according to claim 6 , wherein said main station re-transmits said data when said carrier is received within said prescribed period of time.
8. The data communication system, according to claim 7 , wherein said main station terminates the transmission of said data and effects the transmission of next data when said carrier is received after the same data have been transmitted a prescribed number of times.
9. The date communication system, according to claim 8 , wherein said main station changes said prescribed number of times.
10. The data communication system, according to claim 1 , wherein said plural substations, when said normally received data are received once more, delete said data.
11. The data communication system, according to claim 1 , wherein said plural substations, when said data that could not be normally received are received once more, store said data.