JPH04373346A - Preferential polling request circuit - Google Patents

Abstract

PURPOSE:To preferentially executing polling to a slave station having an important telegraphic message and to speedily transmit the important telegraphic message to a master station by providing the preferential polling request circuit at the slave station of a computer communication network to execute communication according to a polling selecting communication system. CONSTITUTION:When a preferential polling signal 55 is transmitted from a slave station control part 4, which operation is controlled by the computer software of a slave station, to a transmission control part 54, the transmission control part 54 turns a transmission/reception switching gate circuit 50 to a transmission state according to other slave station transmission end information from a transmission end detection circuit 51 and outputs the output command of preferential polling request information to a parallel/serial conversion circuit 53. Then, the preferential polling request information is transmitted through a network to the master station next to 'EOT' showing the end of the telegraphic message at the other slave station. At the master station, the preferential polling request information behind the 'EOT' is read and polling is preferentially executed to the requesting slave station.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a priority polling request circuit for a computer communication network that performs one-to-N communication using a polling and selecting method.

0002

2. Description of the Related Art Conventionally, in a polling/selecting system for computer communication networks, information telegrams are transmitted from slave stations to a master station according to a polling order determined by the master station.

0003

[Problems to be Solved by the Invention] In the conventional polling/selecting method of the computer communication network described above, information telegrams are transmitted from the slave stations to the master station according to the polling order of the master station. Even if it is desired to transmit an important information telegram quickly, it has the disadvantage that it cannot be transmitted until it is polling's turn.

0004

[Means for Solving the Problems] A priority polling request circuit of the present invention is connected to a line from the slave station to the master station of a computer communication network consisting of one master station and a plurality of slave stations. a transmission/reception switching gate circuit that controls the transmission and reception of signals between the
a transmission end detection circuit that detects “SOH” and “EOT”;
A switch circuit that sets priorities in advance, a parallel/serial conversion circuit that converts parallel signals from the switch circuit into serial signals and transmits them to the line, and priority from a slave station control unit whose operation is controlled by computer software. The apparatus includes a transmission control section that controls transmission of the priority polling request signal to the communication network via the parallel/serial conversion circuit and the transmission/reception switching gate circuit based on the polling request signal.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a priority polling request circuit of the present invention, FIG. 2 is a block diagram showing an example of a configuration of a computer communication network to which the present invention is applied, and FIG.
FIG. 3 is a diagram showing an example of a message transmitted to the network of FIG. 2 and a priority polling request format.

The computer communication network shown in FIG. 2 is constructed by connecting a master station 1 and a plurality of slave stations 21, . , a priority polling request circuit 5, and a slave station control section 4 whose operation is controlled by computer software.

The priority polling request circuit 5, as shown in FIG.
OT" (see FIG. 3); a switch circuit 52 that sets priorities in advance; and a transmission switching gate circuit 50 that converts parallel signals from the switch circuit 52 into serial signals. The transmission/reception switching gate circuit 50 is activated by the parallel/serial conversion circuit 53 that transmits to the communication network and the priority polling request signal 55 from the slave station control unit 4.
and a transmission control section 54 that controls transmission of a priority polling request signal to the communication network via the parallel/serial conversion circuit 53.

Next, the operation of this embodiment will be explained. In the initial state, the priority polling request circuit 5 receives information from the network using the transmission/reception switching gate circuit 50, and uses the transmission end detection circuit to detect the heading start "SOH" and the end of transmission "EOT" of the transmission message of other slave stations. 51 and notifies the transmission control unit 54 of the end of transmission of other slave stations. Further, the priority level of the own station is set in advance by the switch circuit 52 and given to the parallel/serial conversion circuit 53.

When the priority polling request signal 55 is sent to the transmission control unit 54 from the slave station control unit 4 whose operation is controlled by the computer software of the slave station, the transmission end detection circuit 51 indicates that the transmission of other slave stations has ended. In response to the notification, the transmission control unit 54 puts the transmission/reception switching gate circuit 50 into a transmission state and issues a command to the parallel/serial conversion circuit 53 to output priority polling request information. This priority polling request information is shown in Figure 3.
It is indicated by the reference numeral 20. Therefore, priority polling request information 2 is next after "EOT" indicating the end of the message of another slave station.
0 is transmitted to the master station 1 via the network. Master station 1
Then, the priority polling request information 20 after "EOT" is read, and polling is performed with priority to the slave station 2 that has made the request.

0010

[Effects of the Invention] As explained above, the present invention provides priority polling request circuits to slave stations of a computer communication network that perform communications based on the polling/selecting method, thereby giving priority to slave stations that have important messages. This has the effect of allowing important messages to be quickly transmitted to the master station by polling.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a priority polling request circuit of the present invention.

FIG. 2 is a block diagram showing an example of a configuration of a computer communication network to which the present invention is applied.

FIG. 3 is a diagram showing an example of a message transmitted to the network of FIG. 2 and a priority polling request format;

[Explanation of symbols]

1　　　Master station 2.Slave station 3 Transmitter receiver 4 Slave station control unit 5 Priority polling request circuit 20 Priority polling request information 50 Transmission/reception switching gate circuit 51 Transmission end detection circuit 52 Switch circuit 53 Parallel/serial conversion circuit 54 Transmission control section 55 Priority polling request signal

Claims (1)

[Claims] 1. A transmission/reception switching gate connected to a line from the slave station to the master station in a computer communication network consisting of one master station and a plurality of slave stations, and controlling transmission and reception of signals between the slave station and the master station. a transmission end detection circuit that detects "SOH" and "EOT" flowing on the line, a switch circuit that sets priorities in advance, and converts parallel signals from the switch circuit into serial signals to connect the line. A priority polling request is sent to the communication network via the parallel/serial conversion circuit and the transmission/reception switching gate circuit by a priority polling request signal from the slave station control unit whose operation is controlled by computer software. 1. A priority polling request circuit comprising: a transmission control section that controls signal transmission.