JPS6243932A - Daisy chain system - Google Patents

Abstract

PURPOSE:To attain immediate release from the standby state by informing a fault state to other subsequent station group if a fault takes place on a communication procedure and detecting that a subsequent station in a sending chance standby state is faulty. CONSTITUTION:A communication control section 1 connected with a communication line and a process control section 2 controlling the communication procedure are included in subsequent stations SST1, SST2.... A process control section 2 is provided with an output line ERO outputting an error signal when a fault takes place on the communication procedure at the communication with a master station and an input line ERI inputting an error signal from other subsequent stations. The subsequent stations SST1, SST2... are connected to an input terminal 4 of a subsequent station connected with an output terminal 3 at its low-adder sequentially by signal lines l1, l2.... If an error on the communication procedure takes place at the communication between the master station and one station in the subsequent station group, the error state is communicated with other subsequent stations awaiting the chance of communication. Thus, a subsequent station receiving the error state is changed into the communication change waiting state immediately based on it to attain efficient operation of the system.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a system configuration in which a master station and a plurality of slave stations are successively connected in series with connection cables to form a day chain, for example, in an online system of a bank machine that is day chained. Concerning communication control between dependent stations.

<Prior art> Fig. 3 shows a main station M and a plurality of slave stations 5STI in remote locations.
, 5ST2. -5TTn are connected in series using connecting cables to create a day chain system, and the main station M is a line termination device DCEI.

Line L21 line termination device DCE2. connected by line L2 to slave station 5STI, and this slave station 5STI
It is connected to the next dependent station 5ST2 via line L3i, and is similarly chained to the dependent station 5STn.

In this system, the main station M and the subordinate station groups 5sTI to 5STn
The communication control is such that the master station M sends a transfer request command to a group of dependent stations, and among the dependent stations that received the command, one of the dependent stations that has the transfer data enters the sending state and other stations has the opportunity to send (in order).

For example, if the dependent stations 5TTI, 5TT2, and STTn have transfer data and the dependent station 5TTI has a transmission opportunity and is communicating with the main station M, other dependent stations 5
TT2 and 5TTn are in a state of waiting for a transmission opportunity.

If a procedural abnormality (error) occurs during communication between the master station M and the slave station 5TTI, the slave station 5TTI will detect the error because it is the station in question. It is possible to return to the initial state immediately after detection. On the other hand, other dependent stations 5TT2 to 5TTn, which have transfer data and are waiting for a transmission opportunity, cannot exit the waiting state immediately because the waiting state for a transmission opportunity is set (the waiting state for a transmission opportunity takes a long time). A timer is set and exits upon this timeout).

This is because if an error occurs in the communication procedure between the main station M and the dependent station STT 1, the dependent stations S T T 2 and S T T n that are waiting for other transmission opportunities will naturally become unable to transmit. Therefore, it is preferable that the transmission opportunity waiting state is immediately released upon the occurrence of the error.

However, in the conventional system described above, even if an error like the one described above occurs while waiting for a transmission opportunity, this waiting state continues for a predetermined period of time, which makes the system inefficient. It had become.

Purpose of the present invention In the above-described system configuration, when an abnormality occurs in the communication procedure, this abnormal state is communicated to other dependent station groups, and the dependent stations waiting for a transmission opportunity are in the abnormal state. It is an object of this invention to improve the efficiency of the system by detecting the waiting state and immediately releasing it from the waiting state.

<Embodiment> FIG. 1 shows the configuration of a system according to the present invention, in which a dependent station 5
STI, 5ST2, . . . are day-chained from the line termination device DCE2 through communication lines L2, L3, L4, .

Each slave station 5STI, 5ST2, etc. includes a communication control unit 1 to which a communication line is connected, and a process control unit 2 that controls communication procedures. The station has an output line ERO for outputting an error signal when an abnormal condition occurs on the station, and an input line ERI for inputting the error signal from another dependent station.

Furthermore, the output line ERO is connected to the output terminal 3 via an OR gate OR, and the input line ERI
is connected to input terminal 4. Further, the input terminal 4 is also connected to the output terminal 3 via the OR gate OR.

Each of the dependent stations 5STI, 5ST2, . ．． 12, . . . are connected in sequence, and receive error signals from higher-order dependent stations and output them to lower-order dependent stations, and the process control unit 2 can detect error conditions based on the error signals.

The operation of this dependent station is shown in the flowchart of FIG. 2. When a transfer request command is received from the main station (HO3T), it is first judged whether or not the own station has transfer data (S,).
When there is data to be transferred, a timer is set to wait for a transmission opportunity. If there is no data to be transferred in S1, the process moves to another routine.

In the transmission opportunity waiting state, it is always judged whether or not the state is ready for transmission (S2). If the state is not ready for transmission, the process moves to S8 and whether or not an error signal has been input from the higher-level station via the input terminal 4. to judge. In this transmission opportunity waiting state, steps S2-83 are cycled through, and when the state is ready for transmission, the process moves to S4 to perform communication processing.

Further, when an error signal is input from another station while waiting for a transmission opportunity, the process control section 2 detects this and immediately exits the waiting for transmission opportunity state and enters the initial state.

On the other hand, if an error occurs during the communication processing in S4 above, that is, during communication with the main station, the process control unit 2 detects an error in the communication procedure (S5), and as a result, the process control unit 2 sends an error signal to the output line ERO. Derive. This error signal is sent to output terminal 3, signal line l. is sent to lower-level stations via. After that, it becomes the initial state.

Further, if no error is detected in S5, the process ends normally.

<Effects> As described above, in the system configuration of the present invention, when an abnormality (error) in the communication procedure occurs during communication between the master station and one of the subordinate stations, a communication opportunity is not available. The abnormal state can be communicated to other waiting dependent stations, and the dependent station that has received the abnormal state can immediately exit from the communication opportunity waiting state based on this, which allows for efficient system operation. obtain.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing the configuration of a daisy chain system according to the present invention, FIG. 2 is a flowchart showing the operation of a daisy chained dependent station, and FIG. 3 is a block diagram showing the configuration of a conventional daisy chain system. It is a diagram. M: Master station, 5STI”-5STn: Slave station, l: Fig. 2-156-1

Claims (1)

[Claims] 1. In a day chain system in which a main station and a plurality of dependent stations are sequentially connected in series through connection cables, the dependent groups mutually transmit signals that can be input/output separately from the day chain cables. The main station and one station of the group of subordinate stations are provided with circuit means for connecting and configuring the line and outputting an error signal to the signal line based on the detection of an abnormality in the communication procedure when in communication with the main station. A daisy chain system characterized in that when an abnormality occurs in a communication procedure during communication with a daisy chain system, the abnormal state can be communicated to other dependent stations waiting for a communication opportunity.