JPH0810676Y2 - Input / output circuit of engine control unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to an input / output circuit that enables an external connection terminal of an engine control device to operate as an output terminal or an input terminal.

"Prior Art" Since a conventional engine control device generally forms a sequence according to a load device, it is necessary to change the number of input / output terminals and a part of the sequence for each load even in the same engine.
Therefore, as shown in FIG. 3, the input circuit section, the output circuit section,
A method in which a control circuit unit, a power supply unit, and the like are unitized according to functions and necessary units are combined has been widely used.

However, in this method, when the number of input or output circuits is insufficient,
The expansion is easy because the expansion is done in units of 8 channels or 16 channels as one unit, but unnecessary terminals are likely to occur and there is a problem in miniaturization.
For this reason, in applications where miniaturization is required, a dedicated board was manufactured exclusively for each model to prevent the occurrence of vacant terminals, but it is necessary to re-examine the board design every time the number of terminals is changed, resulting in a lack of versatility. was there. Therefore, a flexible and less wasteful input / output circuit suitable for a small system has been desired.

An object of the present invention is to provide an input / output circuit of an engine control device which is suitable for a small system, is flexible, and has a small amount of waste of terminals.

According to the present invention, the power output switch is connected to the external connection terminal of the engine control device, and the input detection circuit is connected to the connection point of the external connection terminal and the power output switch. To be done.

When the external connection terminal is used as the input terminal, the power output switch is opened, and when the external connection terminal is operated as the output terminal, the power output switch is closed to operate the load. The input detection circuit and the power output switch function to confirm mutual operation.

"Embodiment" FIG. 1 shows an embodiment of the present invention. A power output switch 13 is connected to an external connection terminal 11 of the engine control device via a backflow prevention diode 12. The other end of the power output switch 13 is connected to the power supply 15 through the power supply terminal 14.

An input detection circuit 16 is connected to a connection point between the external connection terminal 11 and the power output switch 13. When the input detection circuit 16 is configured by a photocoupler, the external connection terminal 11 is connected to the light emitting element 18 of the photocoupler through the detection resistor 17, and the other end of the light emitting element 18 is connected to the ground terminal 19. One end of the light receiving element 21 of the photocoupler is connected to the power supply terminal 22,
The other end is grounded through an output resistor 23 and connected to a control circuit (CPU) not shown in the figure. 25 is an external signal contact, and 26 is a signal power supply terminal. The voltage drop of the output resistor 23 recognizes whether the external signal contact 25 is in a high level signal state or a low level signal state.

During the output operation in which the input / output circuit of the engine control device outputs power to the outside, the power output switch 13 is closed, the external signal contact 25 is opened, and the external connection terminal 11 is loaded with a load, for example, the relay 24. Are connected. Therefore, a power supply 15-power supply terminal 14-power output switch 13-diode 12-external connection terminal 11-relay 24-a ground loop is constructed and operates as an output circuit, and relays under the control of the power output switch 13 24 will be activated.

During an input operation in which a signal is input from the outside to the input / output circuit of the engine control device, the power output switch 13 is opened while the external signal contact 25 is closed, and the external connection terminal 11 is connected.
The signal power supply terminal 26 is connected to. Therefore, power supply terminal 26-external signal contact 25-external connection terminal 11-resistor
A loop consisting of 17-light emitting element 18-ground terminal 19 operates as an input circuit, and the signal is isolated by a photocoupler.
By the light receiving element 21 and the output resistor 23, the state of the external signal contact 25 is taken out as a high level signal or a low level signal,
Input to U.

Here, the state monitoring when the external connection terminal 11 of the engine control device is used as an output terminal will be described.
When the power output switch 13 is normal, the input detection circuit 16 detects a high level when the power output switch 13 is turned on, while the input detection circuit 16 detects a low level when the switch is turned off. . However,
If any abnormality occurs in the power output switch 13,
Input detection circuit 16 even when power output switch 13 is turned on
Does not detect the high level, or the input detection circuit 16 detects the high level when the switch is turned off. Therefore, assuming that the input detection circuit 16 is normal, whether the power output switch 13 is normal or abnormal based on the relationship between the ON / OFF state of the power output switch 13 and the level of the input detection circuit 16. Can be recognized.

As described above, when both the power output switch 13 and the input detection circuit 16 are normal, the power output switch
It is possible to recognize whether the power output switch 13 is normal or abnormal based on the relationship between the on / off state of 13 and the level of the input detection circuit 16. This means that it is possible to recognize whether the input detection circuit 16 is normal or abnormal, assuming that the switch 13 is normal. Therefore, when the external connection terminal 11 of the engine control device is used as the input terminal, the input detection circuit 16 is normal by temporarily turning on the power output switch 13 before using it as the input terminal. It is possible to recognize whether it is abnormal or abnormal.

A plurality of circuits shown in FIG. 1 are assembled and used as one substrate as shown in FIG.

As described above, since the external connection terminal 11 can be used as both an input terminal and an output terminal, it is possible to assign signals to each terminal according to the required amount of input terminals and output terminals. The output terminals and the output terminals can be flexibly allocated as needed, and wasteful terminals can be suppressed and a dense terminal arrangement can be realized.

The power output switch 13 may be mechanical or electronic.

"Effect of device" As described above, according to this device, each terminal for external connection is connected.
Since 11 can be used for both input and output for each terminal,
The flexibility of the terminals is high, and the terminals can be accommodated within the unit before the addition of the unit, and the generation of unnecessary terminals can be reduced.

When used as an output, the output state of the terminal can be constantly monitored by using the input detection circuit 16, so that the failure can be found quickly. Also when used as an input, a self-check can be performed at startup.

The input / output circuit of the engine control device according to the present invention can eventually use the external connection terminal 11 as an input terminal or an output terminal as required. It is possible to constantly monitor the state of the power output switch 13, which is said to have the most frequent failures, and the power output switch 13 and the input detection circuit 16 are in a relationship of mutually confirming operation. Therefore, it can be said that it is suitable as an input / output circuit of the engine control device.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing an example in which the input / output circuit of the present invention is unitized, and FIG. 3 is a front view showing a conventional engine control device.

Claims (1)

[Scope of utility model registration request] 1. An external connection terminal of an engine control device and one terminal of a power output switch are interconnected via a backflow prevention diode, and the other terminal of the power output switch is connected to a power source. An input / output circuit of an engine control device, wherein an input detection circuit is connected between an interconnection point between an external connection terminal and a backflow prevention diode and ground.