JPH021653A - Data link unit - Google Patents

Abstract

PURPOSE:To continue the action of data link without deteriorating a whole data link system by providing a standby cable to a data link unit in addition to a normal cable. CONSTITUTION:When abnormality occurs in the cables of slave stations 11b and 11c due to disconnection and the like, the slave station 11c informs a master station 10 of error detection. The master station 10, which has received information, is connected to the slave station 11c by using a cable 13a used at an abnormal time through a receiver 15, selection units 18, 7 and 19 and a driver 17, which are respectively used at the abnormal time. Thus, the slave station 11b, in which abnormality has occurred, is bypassed by the cable 13b. Consequently, an abnormal part is detached by using the cable 13b and the action of the data link is continued.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data link unit of a programmable controller.

(Prior Art) FIG. 3 shows a system diagram of a programmable controller using a conventional data link unit.

In the figure, (1) indicates the master station of the data link system,
(2a) to (2f) each indicate a slave station, and each unit is connected by a cable (3). Each slave station is provided with a receiver (4) for receiving data from the previous station and a driver (5) for sending data to the subsequent station.

Further, an internal circuit (6) for performing various signal processing within the link unit and a unit (7) for performing signal selection are provided. Furthermore, (8) shows the flow of data. The internal structure of each slave station is the same.

Next, the operation of the above-mentioned conventional unit will be explained. master station(
The data sent from the driver (5) of 1) is transmitted to the receiver (4) of the slave station (2a) via the cable (3). The slave station (2a) processes the received data in an internal circuit (6) and sends the data to the next foal (2b) via the driver (5).

Here, the unit (7) that performs signal selection provided in the slave station (2a) is set in such a way that the received data is sent as is from the driver (5) at the time of reception. This is because the data is not necessarily destined for the own station, so the data sent by the master station (1) or the data sent by the previous slave stations needs to be sent to the next slave station and the master station as well.

On the other hand, when the local station sends data, the receiver (4) and driver (5) are disconnected and the data from the internal circuit (6) can be sent via the unit (7). It needs to be set in shape.

By performing such a series of processing on each slave station, the master station (1
) and the slave stations (2a) to (2f).

[Problem to be solved by the invention]

Conventional data link units are configured as described above, so if a link unit fails at a certain point, a cable is pulled out, or a wire is disconnected, the entire data link system will go down. was there.

This invention was developed to solve the above problems, and even if a part of the link fails due to a cable or link unit failure during normal use, the entire data link system can be brought down. To provide a data link unit that can continue a link by bypassing a part that has caused a failure without any problems.

(Means for Solving the Problems) A data link unit according to the present invention is provided with a second receiver and a second driver having the same functions in addition to a receiver and a driver that perform a normal data link, and further includes a first receiver and a second driver that have the same functions. , a receptacle selection unit connected to the second receiver for selecting and switching between the two receivers;
A feed port selection unit is provided, which is connected to the second driver and performs switching selection between both drivers, and is connected from the second receiver and the second driver via third and fourth cables, respectively, in the event of an abnormal operation. It is configured to transmit and receive signals to and from a master station or a slave station.

[Effect]

In the data link unit of the present invention, when the station or cable connected to the bypass cable becomes abnormal, the bypass cable is used to disconnect the abnormal part and continue the data link operation.

〔Example〕

A practical example of this invention will be described below with reference to FIG.

FIG. 1 is a block diagram of a data link unit showing an embodiment of the present invention. In the figure, (10) represents the master station of the data link system, (lla) to (llf
) indicates the slave stations, and the master station (1G) and slave station (
lla) is connected by a cable (12) normally used for data link. Also (13a
), (13b) are cables used in place of normal cables in preparation for abnormal operations, and are receivers (14) and (13b) used in abnormal operations that have the same functions as the receiver (14) and driver (16) used during normal operations. 15) and a driver (17), respectively.

Therefore, the receiver (15) is used when there is an abnormality and a bypass cable (13a) is used. Furthermore, the driver (17) is used when using the bypass cable (13b) in the event of an abnormality. In this way, there is a receiver (14) in the slave station (lla) that is used during normal operation.
), a driver (16), a receiver (15) and a driver (17) that are used in the event of an abnormality, and therefore a unit for switching these is provided. (18) is a unit for switching between receivers (14) and (15) to select a data reception;
19) is a unit for switching between the drivers (16) and (17) to select the sending port of the transmission signal. 1st
In the embodiment shown in the figure, a receiver (15) and a driver (1) provided in a slave station (lla) are used in the event of an abnormality.
7) are cable (13a) and cable (1), respectively.
3b) are connected to the driver and receiver of the master station (10) and slave station (llc), respectively, which are used in the event of an abnormality. In other words, the slave station (11a) and the slave station (llc) are connected to each other by bypassing the slave station (llb).

Next, the operation of the data link unit having such a configuration will be explained. FIG. 2 shows a flowchart for explaining the operation of the data link system when an abnormality occurs, that is, when an error is detected. Figure 2 (A) shows the operation of the slave station that detected the error, Figure 2 (B) shows the operation of the master station, and Figure 2 (C) shows the response to the loop switching request from the master station. The operation of the slave station that performs loop switching is shown in each figure.

First, if there is no abnormality in the loop, both the master station (lO) and slave stations (lla) to (llf) shown in Fig. 1 are connected to the receiver (14) and driver (16) that are used during normal operation. Communication is carried out using a cable (12).

At this time, the unit (18) for selecting the receiving signal receiving port is connected to the receiver (14) used during normal operation, and the unit (9) for selecting the transmitting signal receiving port is connected to the driver (18) used during normal operation. It is connected.

The function of the signal selection unit (7) is the same as in the conventional case shown in FIG. 3, and the communication operation during normal operation is also the same as in the conventional case.

Next, the operation when an abnormality occurs will be explained using FIGS. 1 and 2. In this embodiment, the slave station (llb)
The explanation will be based on the assumption that the cable between the terminal and the slave station (llc) has an abnormality due to a disconnection or the like.

In this case, the slave station (llc) performs error detection according to the flowchart of FIG. 2(A) in order to detect an abnormality in the loop (step 201). In this case, since the error has not yet been detected (step 202), the receiving side loop is switched (step 203) and the error detection is reported to the parent Ji (10) (step 204).

The slave station (llc) that detected the error continues error detection until the error disappears (step (201)), but since it has already determined whether the error has been detected (step 202).
), the error detection is reported to the master station (IO) only at the first error detection (step 204).

As shown in FIG. 2(B), when the master station (lO) receives the error detection report (step 211), it sends a loop switching request to the previous slave station (llb) that reported the error detection ( Step 215). In contrast, the slave station (llb
) receives a loop switching request according to the flow shown in FIG. 2 (C) according to the operation of the slave station (11, c) requesting loop switching (step 221), so the loop switching on the transmitting side is performed. (Step 222).

However, if the connection as shown in FIG. 1 is maintained, the loop will not become normal, so the slave station (llc) does not report the error recovery to the master station (10) (step 206). Therefore, the master station (10
) sends a switching request (step 212), but even after waiting for a certain period of time (step 213), it does not receive an error recovery (step 214), so it loops back to the previous slave station (11a). Submit a request (
Step (215). The slave station (lla) receives the loop switching from the master station (lO) (step 221) and switches the loop from the transmitting side (step 222).

As a result, the slave station (llc) which detected the error makes an error recovery request to the master station (lO) in order to detect error recovery (step 205) (step 206).

After this series of operations, the master station (IO), which has learned that the loop has become normal, resumes the data link. In addition, in the above-mentioned embodiment, explanation was given of the case where the slave stations are connected in the form of a strip that bypasses the cable, but if the connection is made with the neighboring station as shown in the cable (13a) shown in Fig. 1, the normal It can be used as a spare for the cable you are currently using.

Further, in the embodiment shown in FIG. 1, a data link system using a single loop has been described, but a data link system using a multiplex loop can also be realized with a similar configuration.

〔Effect of the invention〕

As explained above, according to the present invention, the data link unit is configured so that a spare cable can be connected in addition to a normal cable, so that even if a part of the data link system fails, the failed part can be repaired. The effect is that reliability can be improved by disconnecting and connecting and preventing the entire data link system from going down.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a data link unit according to an embodiment of the present invention, FIG. 2 is a flow chart for explaining the operation when error 7 occurs, and FIG. 3 is a block diagram showing the configuration of a data link unit according to an embodiment of the present invention. It is a system configuration diagram of the system used. (lO) is the master station, (lla) ``' (1, 1f) is the slave station, (12) is the cable used in normal conditions, (13a), (13b) is the cable used in abnormal conditions, (14), ( 15) is a receiver, (16) and (17) are drivers, (18) is a unit for selecting a receiving signal receiving port, (1
9) is a unit that selects the sending port of the transmission signal.

Claims (1)

[Claims] During normal operation, the first receiver receives a signal sent via the first cable from an adjacent master station or slave station, performs predetermined processing, and then transmits the signal from the first driver to the second cable. In a data link unit that transmits a signal to another adjacent slave station or a master station via a second receiver and a second driver having the same function,
, a receptacle selection unit connected to the second receiver to select switching between both receivers, and a feed selection unit connected to the first and second drivers to select switching between both drivers, and in the event of an abnormal operation, the A data link unit configured to transmit and receive signals from a second receiver and a second driver to a master station or a slave station connected via third and fourth cables, respectively.