JPS5831635A - Method and apparatus for multibranch data transmission - Google Patents

Abstract

PURPOSE:To avoid apparent traffic on an outgoing line from being increased, by performing polling at a master station, only when a telegraphic message is generated at a slave station. CONSTITUTION:A timer circuit 7 in a slave station 2 is turned on for a prescribed time every time polling is received from a master station 1. Further, a polling request circuit 8 generates a telegraphic message at the slave station 2 and transmits a polling request to the master station 1 only when the output of the circuit 7 is absent. A polling transmission circuit 10 of the master station 1 receives the polling request from the slave station 2 and transmits polling to the said salve station when the address of the slave station is normally received, and to all the slave stations, if not normally received. Through the constitution abov, since the master station performs polling only when a telegraphic message is generated at the slave station, the increase in apparent traffic on an outgoing transmission line 5 hardly takes place. Since the slave station is subjected to polling when the telegraphic message is generated at the slave station, useless delay can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-branch data transmission system in which polling of a slave station is carried out immediately after a message is generated in the multi-branch data transmission system. For example, as stated in the Nippon Telegraph and Telephone Paste Corporation's technical reference materials for using dedicated dedicated line specified communication lines, signals from a master station can be received by all slave stations, but signals from slave stations can only be received by the master station. In many cases, a line configuration method that allows this is used. When such a line configuration method is adopted, a so-called polling method has been commonly used as a transmission control procedure in which the presence or absence of a message is sequentially checked from the closest terminal to each slave station.

However, this polling method has the following drawbacks. First, the downlink transmission path from the master station to the slave station is mostly occupied by polling rather than telegrams, which is undesirable because, for example, when the downlink transmission path is multiplexed, the apparent traffic increases. ＃￥
2, a certain slave station sends a message lJ:, 1. If! ! In this case, the transmission of the message becomes possible only when the slave station is polled, and therefore the transmission is delayed on average by half the polling period, but in most cases it is possible to send the message by one polling period. This is an unnecessary delay because a message is generated in only one slave station at most during the cycle.

The present invention is intended to solve the above-mentioned drawbacks, and its purpose is to provide a multi-branch data transmission system characterized in that polling is performed only when a message is generated in a slave station.

In order to achieve this purpose, the multi-branch data transmission system of the present invention is such that the slave station has a timer that is turned on for a certain period of time on the screen that receives polling for any slave station from the master station;
A polling request is sent to the master station only when a message is generated in the slave station and the timer is off, and the master station receives the polling request from the slave station and sends the polling request to the slave station when the slave station address is received normally. The feature is that polling is sent to the station, and to all slave stations if the polling cannot be received normally.

Examples will be described in detail below.

FIG. 1 is an explanatory diagram of a multi-branch data transmission system to which the present invention is applied, in which 1 is a master station, 2, 3 and 4 are slave stations, 5 is a downlink transmission path, and 6 is an uplink transmission path.

FIG. 2 shows an embodiment of a slave station device of the multi-branch data transmission apparatus of the present invention, and corresponds to 2 to 4 in FIG. For the sake of simplicity, only the part related to the transmission of the polling request signal is shown, and the part related to the transmission and reception of the message is omitted.This part is exactly the same as the conventional transmission device using the polling method.

In Figure 2, numeral 7 is a timer circuit that is turned on for a certain period of time every time it receives polling for any slave station from the master station. Specifically, the fixed time is the maximum time required to transmit a message from any slave station through an uplink transmission path. 8 is a polling request transmitting circuit that transmits a polling request to the master station only when a message is generated in the slave station and the output of the timer circuit 7 is off. 9 is a message input terminal.

FIG. 3 shows an embodiment of the master station device of the multi-branch data transmission apparatus of the present invention, and corresponds to 1 in FIG.

For the sake of simplicity, only the part related to polling transmission is shown and the part related to transmission and reception of telegrams is omitted, but this part is exactly the same as the conventional polling type transmission device. In Figure 93, 10 receives a polling request signal from a slave station, and when the slave station address is received normally, the polling is sent to that slave station, and when it is not received normally, the polling is sent to all slave stations. It is a circuit.

With the above configuration, the master station performs polling only when a message occurs in the slave station, so the first drawback of the conventional polling method mentioned above, that is, the apparent traffic on the downlink transmission path does not increase, and When a message is generated at a slave station, in most cases the slave station is polled immediately, and even if not, the slave station is polled after the same amount of time as in the conventional polling method, so the second disadvantage of the conventional polling method mentioned above also exists. It became possible to eliminate it.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the entire multi-branch data transmission system to which the present invention is applied, FIG. 2 is a multi-branch data transmission device for a slave station according to an embodiment of the present invention, and FIG. This is also an embodiment of the present invention for multi-branch data transmission for the master station.

Claims (1)

[Scope of Claims] 1) The slave station has a timer that is turned on for a certain period of time each time it receives polling for any slave station from the master station, and when a message is generated at the slave station and the timer is activated. A hauling request is sent to the master station only when it is off, and the master station receives a polling request from a slave station. If the slave station address is received normally, it is sent to the slave station, and if it is not received normally, it is A multi-branch data transmission method characterized by transmitting polling to a slave station. 2) A timer/circuit that is turned on for a certain period of time each time a polling directed to a slave station is received from a master station, and A multi-branch data transmission slave station device that uses a polling request transmitting circuit that transmits a polling request to a master station only when the output of the timer circuit is off. 3) Use a polling signal circuit that receives a polling request from a slave station and sends polling to that slave station when the slave station address is received normally, and to all slave stations when the address is not received normally. Multi-branch data transmission station equipment.