JPH03204005A - Relay output circuit for programmable controller - Google Patents

Abstract

PURPOSE:To simplify the circuit constitution by using a power supply of an interface circuit also as the power supply for drive of a relay. CONSTITUTION:The output signal received from a control unit CU is transmitted to the relays 16a and 16b via an interface circuit 12 and the drives 14a and 14b. Thus a coil is driven. In this case, both relays 16a and 16b are directly driven by a DC power supply 13 or 5V. Therefore the current flowing in a driving state is small and the especially large capacity is not needed for both drivers 14a and 14b of the precedent stage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to relay output circuits for programmable control devices.

BACKGROUND OF THE INVENTION FIG. 2 is a circuit diagram showing the configuration of a relay output circuit 1 of a conventional programmable control device. The interface circuit 2 is a circuit for smoothly transmitting and receiving signals between the control unit (includes a CPU and executes calculations, etc.) CU, which is the main body of the programmable control device, and an external device. A DC voltage power supply 3 (3) is used as a power supply for this interface circuit 2.

Drivers 4a and 4b that amplify the output signal output from the interface circuit 2 to an appropriate level are connected to the next stage of the interface circuit 2, and each driver 4a and 4b is connected to the output signal via a photocoupler 5a and 5b, respectively. and are connected to corresponding relays 6a and 6b. As the relays 6a and 6b, those having a driving power of 0.2 W or more are usually used. Contact points of each relay 6a, 6b are connected to corresponding load-side circuits 7a, 7b, respectively.

A 24V DC voltage power source 8 is externally connected to the relay output circuit 1 for driving the relay.

In the relay output circuit 1, the output signal sent from the control unit CU is transmitted to the photocouplers 5a, 5b via the interface circuit 2, drivers 4a, 4b, and the photocouplers 5a, 5b are driven by the output. As a result, the coils of relays 6a and 6b are driven. When the coils are driven, the contacts of the relays 6a and 6b are turned on, and as a result, the load-side circuits 7a and 7b are closed, and the loads Ll and L2 are driven.

The DC voltage power supply 8 for driving the relay in the relay output circuit 1 may be replaced by the power supplies 9a and 9b of the load side circuits 7a and 7b, and the photocouplers 5a and 5b are the power supplies of the load side circuits 7a and 7b. It plays a role of insulating between 9a, 9b and the DC voltage power supply 3 of the interface circuit 2.

Problems to be Solved by the Invention As mentioned above, in the above relay output circuit, the power supply 8 for driving the relay may be replaced by the power supplies 9a and 9b on the load side, but the power supplies 9a and 9b on the load side are ■Ya20
In the case of a 0V AC power source, it is necessary to separately prepare a power source 8 as shown in FIG. 2, which has the problem of complicating the configuration.

In addition, power supplies 9a and 9 on the load side are used as relay drive power supplies 8.
Even if b can be substituted, the load side power supplies 9a and 9b can be replaced by the power supply terminals (+24V, 0V) 10a,
There is a problem in that wiring to be connected to 10b is required, and the wiring process is troublesome. Furthermore, in this case, as described above, it is necessary to insulate between the load side power supplies 9a, 9b and the interface circuit 2 side power supply 3 using the photocouplers 5a, 5b, resulting in an increase in the number of circuit components. has.

Therefore, an object of the present invention is to provide a programmable relay output circuit for a control device that does not require an external power source for driving the relay and has a simple circuit configuration.

Means for Solving the Problems The present invention provides a programmable control device that turns on and off a relay using an output signal output from an interface circuit via a driver, and drives a load by turning on and off the relay. The relay output circuit for a programmable control device is characterized in that the relay uses a relay with low driving power as the relay, and the power source used for the interface circuit is shared as the power source for driving the relay.

Function According to the present invention, the power supply of the interface circuit is shared as the power supply for driving the relay, so an external power supply is not required, and a photocoupler for insulating between the power supply of the interface circuit and the power supply on the load side is also unnecessary. become. Also: Since a relay with low driving power is used, the required current is small and a driver with a small output capacity is sufficient.

Embodiment FIG. 1 is a circuit diagram showing the configuration of a relay output circuit 11 of a programmable control device which is an embodiment of the present invention.

In FIG. 1, an interface circuit 12 is a circuit for smoothly transmitting and receiving signals between a control unit CU, which is the main body of a programmable control device, and an external device. It is used as a power source for this interface circuit 12.

Drivers 14a and 14b that amplify the output signal output from the interface circuit 12 to an appropriate level are connected to the next stage of the interface circuit 12, and each driver 14a and 14b is connected to a corresponding relay 1.
6a and 16b. That is, the photocoupler in the conventional example is omitted here. Furthermore, here, relays 16a and 16b with low driving power (approximately 0.12W in this case, compared to 0.2W in the conventional case) are used.

Further, the power source 13 of the interface circuit 12 is commonly used as a power source for each of the relays 16a and 16b. That is,
A DC voltage power source 13 is connected to the coil of each relay 16a, 16b.

The configuration in which the contacts of each relay 16a, 16b are connected to the corresponding load-side circuit 16a, 16b is the same as in the conventional case.

Next, the operation of the relay output circuit 11 will be explained.

The output signal sent from the control unit CU is transmitted to the relays 16a, 16b via the interface circuit 12, drivers 14a, 14b, and as a result, the relays 16a, 1
The coil 6b is driven.

When the coil is driven, the contacts of the relays 16a and 16b are turned on, and as a result, the load side circuits 17a and 17b are closed and the loads LL and L2 are driven.

In this case, the relays 16a and 16b are directly driven by the 5cm DC voltage power supply 13, so the current i flowing during driving is 1-0.12W15V24mA-(1
) is small, so the driver 14a14 in the preceding stage is small.
Relay 16 is also sufficient even if a high-capacity output type CMO3 integrated circuit is used without using a special large-capacity one.
a, 16b can be driven.

Incidentally, in the configuration of the relay output circuit 11, if the relays 16a and 16b are of the drive power 0.2W used in the conventional example, the current i flowing during driving is i=0.2W15V=40mA -
(2>), and high-capacity output type drivers are required as the drivers 14a and 14b.It can also be seen that the current capacity of the 5V DC voltage power supply 13 also becomes large.

Effects of the Invention As described above, according to the relay output circuit of the programmable control device of the present invention, the power source of the interface circuit is shared as the power source for driving the relay, and a relay with low driving power is used. There is no need for an external power supply or photocoupler, and the current capacity of drivers and other devices can be small, allowing for a simplified configuration, a reduction in the number of circuit components, cost reduction, and miniaturization of the device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of a relay output circuit of a programmable control device according to an embodiment of the present invention, and FIG. 2 is a circuit diagram showing the configuration of a relay output circuit of a conventional programmable control device. be. 11...Relay output circuit, 12...Interface circuit, 13...DC voltage power supply, 14a, 14b...Driver, 16a, 16b-Relay

Claims (1)

[Claims] A relay is turned on and off by an output signal output from an interface circuit via a driver, and the relay is turned on and off.
A relay output circuit of a programmable control device that drives a load when it is off, characterized in that a relay with low driving power is used as the relay, and the power source used for the interface circuit is shared as the power source for driving the relay. A relay output circuit for a programmable control device.