JPS5916285B2 - terminal control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the configuration of a terminal control device for a sequence control system using a multiplex transmission method.

Figure 1.

FIG. 2 is a diagram showing the principle of a general multiplex transmission type sequence control system. In the figure, 1 is a sequence controller, 21022 to 2m are terminal control devices, and 3 is a time division signal transmission line for transmitting and receiving signals between the sequence controller 1 and the terminal control device. Consisting of electrical wires. 211, 212-21n1,
221, 222-22n2, 231, 232-23n3
, 2m1, 2m2, ~2mnm are control objects divided into m groups 5, each of which is controlled by the terminal control device 21, 22.
~2m.

Actual control targets include sensors such as limit switches and proximity switches, and loads such as solenoids, relays, and motors.
Depending on what is connected to which terminal, it is necessary to adopt a suitable configuration, or to separate the connection terminals for sensors from the connection terminals for loads.

The operation of the device configured as described above will be explained below. 5
FIG. 2 shows a case where the internal structure of the terminal control device is configured according to the type of controlled object to be connected.

In FIG. 2, 2 is a terminal control device, and 4 is a signal processing circuit, which has functions such as generation, transmission, reception, and reproduction of time-division signals. 6, □ is a transistor, and a drive signal is obtained from the 0 signal processing circuit 4.

8, 9, 10, 11. 12, 13 are connection terminals, among the above terminals, 8 is a power supply terminal, 9, 11 are terminals for connecting loads 15, 17 such as solenoid coils, 10, 12, 1
3 are terminals for connecting the switches 16, 18, and 19, respectively.

In FIG. 2, for example, in order to energize the solenoid 15, a time-division signal is transmitted from a sequence controller (not shown) via a time-division signal transmission line 3, which is received and reproduced by a signal processing circuit 4. By turning on transistor 6, solenoid 15 is energized. Further, the on/off status of the switch 16 is converted into a time-division signal by the signal processing circuit 4 and transmitted to a sequence controller (not shown) via the time-division signal transmission line 3. However, the configuration of the terminal control device shown in Fig. 2 is affected by the connection method of the controlled object, which not only hinders the production of a standard terminal control device, but also requires small changes such as the terminal 12.
Even if it is desired to connect a solenoid to the switch 18 instead of the switch 18, there are some inconveniences in use, such as having to replace the terminal control device with a new one.

Therefore, the method shown in FIG. 3 can be considered.

In this system, output terminals 9a, 10a to 13a and input terminals 9b to 13b are provided independently.

Therefore, in order to realize the same function as shown in FIG.
6, 18, and 19 should be connected. If a terminal control device having such a configuration is manufactured as a standard product, it will be possible to deal with all kinds of distribution of control objects, and it will be easy to change connections. However, if such a configuration is adopted, the number of terminals will inevitably increase, which will be a major hindrance to miniaturization of the terminal control device.
A major feature of this type of terminal control device is that it is small and can be installed very close to the object to be controlled, and from this point of view, the configuration shown in FIG. 3 cannot be called optimal. The present invention has been made in view of the above points, and provides an optimal configuration for a terminal control device of a sequence control system using a multiplex transmission method.

FIG. 4 shows an embodiment of a unit circuit according to the present invention. In contrast to FIG. 2, the circuit related to the transistor 6ff in FIG. 2 is extracted and shown.

In FIG. 4, the base 6B and collector 6C of the transistor 6, which is a switching element, are both connected to a signal processing circuit (
(not shown). Further, a power source 14 is connected to the emitter serving as one end of the switching element, and a resistor 6R is connected between the emitter and the collector. The embodiment shown in FIG. 4 is an example in which a solenoid coil 15 is connected to this unit circuit as a load to be controlled. In FIG. 4, the transistor 6 is turned on and off by a signal applied to the terminal 6B, and the solenoid coil 15 is driven and stopped. In this case, since the terminal 6C, which is the other end of the switching element, is connected to the input terminal of the signal processing circuit, it is possible to detect whether or not the solenoid coil 15 is out of order. That is, when the solenoid coil 15 is short-circuited, the voltage at the terminal 6C remains at ground potential even if the transistor 6 is turned on. Therefore, by monitoring the voltage at the terminal 6C with a signal processing circuit, Short circuit failures can be detected. Further, if the solenoid coil 15 has a disconnection failure, a voltage is applied to the terminal 6C via the resistor 6R even though the transistor 6 is off, so that the disconnection failure of the solenoid coil 15 can be similarly detected. Next, FIG. 5 shows the circuit configuration of FIG. 4 in which a switch 16 is connected as a control object instead of the solenoid coil 15. In this configuration, transistor 6 is not turned on. When the switch 16 is closed, the terminal 6C
becomes the ground potential, and when the switch 16 is opened, the terminal 6C becomes the power supply voltage. Therefore, by monitoring the voltage at the terminal 6C with a signal processing circuit, it is possible to detect whether the switch 16 is open or closed. If a terminal processing device is configured using the unit circuits shown in FIGS. 4 and 5, the result will be as shown in FIG. 6.

The terminal processing device shown in FIG. 6 can arbitrarily use each terminal for a load or a switch, and also has the ability to detect failures. Although the above description has been made regarding the case where a PNP transistor is used to drive the load, it is clear that the present invention can also be realized using an NPN transistor or other composite transistor circuit.

As described above, the present invention uses, as a unit circuit, a switching element driven by a signal processing circuit and a resistor connected in parallel with the switching element, one end of the switching element being connected to a power supply, and the other end being connected to a power supply. The end is grounded via a controlled object and connected to the signal processing circuit, and when the controlled object is a load, the signal processing circuit opens and closes the switching element based on commands from the sequence controller. When the control target is a switch, the switching element is always open based on the command from the sequence controller, and the voltage at the other end of the switching element is detected. Since the opening/closing of the switch to be controlled is detected and this information is sent to the sequence controller, the output terminal of the terminal control device can be used as either an output terminal or an input terminal depending on the command content of the sequence controller. It has the advantage of being highly versatile.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a sequence control system using a multiplex transmission method, FIGS. 2 and 3 are block diagrams of a conventional terminal control device, and FIGS. 4 and 5 are unit circuit diagrams of a terminal control device according to the present invention. A configuration diagram showing an example, FIG. 6 is the same as the above-mentioned FIG. 4,
FIG. 6 is a configuration diagram showing an embodiment of a terminal control device configured with the unit circuits shown in FIG. 5; In the figure, 1 is a sequence controller, 2 is a terminal control device, 4 is a signal processing circuit, 6 is a transistor, 6B,
6C is a terminal, 6R is a resistor, 14 is a power source, 15, 17 are solenoid coils, and 16, 18, 19 are switches.

Claims (1)

[Claims] 1. A signal processing circuit connected to the sequence controller via a time-division signal transmission line, a switching element that is driven by the signal processing circuit to open and close, and a resistor connected in parallel with the switching element, One end of the switching element is connected to a power source, and the other end is grounded via a controlled object and connected to the signal processing circuit, and when the controlled object is a load, the signal processing circuit The power supply is controlled to supply power to the load by opening and closing the switching element based on commands from the sequence controller, and if the controlled object is a switch, the switching element is always open based on the command from the sequence controller. The terminal control device also detects the opening and closing of the switch to be controlled by detecting the voltage at the other end of the switching element, and sends this information to the sequence controller.