CN212846474U

CN212846474U - Multifunctional output control circuit for PLC

Info

Publication number: CN212846474U
Application number: CN202021702459.3U
Authority: CN
Inventors: 徐成; 陆晓峰; 盛旭东; 严德新; 孔骁勇; 史幼迪
Original assignee: Shanghai 3e Automation Control Engineering Co ltd
Current assignee: Shanghai 3e Automation Control Engineering Co ltd
Priority date: 2020-08-14
Filing date: 2020-08-14
Publication date: 2021-03-30
Anticipated expiration: 2030-08-14

Abstract

A multifunctional output control circuit for PLC is composed of a current limiting resistor R1, a current limiting resistor R2, an optocoupler U1 and an optocoupler U2; the current-limiting resistor R1 is connected in series with the input end of the optocoupler U1 and is respectively connected to the control end EA and the common end COM; the current limiting resistor R2 is connected in series with the input end of the optocoupler U2 and is respectively connected to the control end EK and the common end COM; the output ends of the optical coupler U1 and the optical coupler U2 are connected in anti-parallel and are respectively connected to the output end OA and the output end OK. The invention realizes multiple control functions of forward direct current on-off control, forward direct current on-off and follow current control, reverse direct current on-off and follow current control, alternating current on-off control and the like in the same hardware component through different control levels. The three fixed output control circuit forms of the transistor output, the bidirectional thyristor output and the relay output of the current PLC can be comprehensively replaced.

Description

Multifunctional output control circuit for PLC

Technical Field

The invention relates to the technical field of industrial measurement and control, in particular to a multifunctional output control circuit for a PLC.

Background

The Programmable Logic Controller (PLC) is widely applied to the field of industrial measurement and control due to high reliability and convenient use. The output control circuit of the PLC generally has the following three circuit forms: (1) a relay output control circuit; (2) a transistor output control circuit; (3) bidirectional thyristor output control circuit. The relay output control circuit is in a contact control mode, is suitable for on-off control of various alternating current and direct current signals, is limited by the structure, can only realize slow (generally more than 10ms) on-off control, and has a limited service life (generally 100 ten thousand times); the transistor output control circuit is in a contactless control form, has high response speed and almost no life limit, but is only suitable for on-off control of direct current signals; the bidirectional thyristor output control circuit is in a contactless control form, has high response speed and almost no service life limitation, but is only suitable for on-off control of alternating current signals due to the limitation of the control characteristic of the thyristor. Once the output circuit of all the PLCs is determined, the signal control form of the PLCs cannot be changed any more, and the use flexibility of the PLCs is greatly limited.

Disclosure of Invention

In order to solve the above drawbacks, the present invention provides a multifunctional output control circuit for a PLC, which is characterized in that: a multifunctional output control circuit for PLC is composed of a current limiting resistor R1, a current limiting resistor R2, an optocoupler U1 and an optocoupler U2; the current-limiting resistor R1 is connected in series with the input end of the optocoupler U1 and is respectively connected to the control end EA and the common end COM; the current limiting resistor R2 is connected in series with the input end of the optocoupler U2 and is respectively connected to the control end EK and the common end COM; the output ends of the optical coupler U1 and the optical coupler U2 are connected in an anti-parallel mode and are respectively connected to the output end OA and the output end OK; when the control end EK is in long connection with the common end COM, no current passes through the input end of the optocoupler U2, the output end of the optocoupler U2 is always in an off state, and the control level of the control end EA is high or low at the moment, so that the current at the input end of the optocoupler U1 can be changed, the on or off of the output end of the optocoupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, and the whole output control circuit is equal to a common PLC transistor collector open-circuit forward output control; when the control end EK is connected with a high level for a long time, the output end of the optical coupler U2 is always in a conducting state, the control level of the control end EA is high or low, the current at the input end of the optical coupler U1 can be changed, so that the on or off of the output end of the optical coupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, meanwhile, the conduction of the output end of the optical coupler U2 can provide the follow current flowing from the output end OK to the output end OA, and the whole output circuit is equal to a normal forward output control circuit of a PLC transistor collector; when the control end EA is in long connection with the common end COM, no current passes through the input end of the optocoupler U1, the output end of the optocoupler U1 is always in an off state, and the control level of the control end EK is high or low at the moment, so that the current at the input end of the optocoupler U2 can be changed, the on or off of the output end of the optocoupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, and the whole output control circuit is equal to a common PLC transistor collector open-circuit reverse output; when the control end EA is connected with a high level for a long time, the output end of the optical coupler U1 is always in a conducting state, the control level of the control end EK is high or low, the current at the input end of the optical coupler U2 can be changed, so that the on or off of the output end of the optical coupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, meanwhile, the conduction of the output end of the optical coupler U1 can provide the follow current flowing from the output end OA to the output end OK, and the whole output circuit is equal to a reverse output control circuit of a common PLC transistor; when the same control level is sent to the control end EA and the control end EK, the output ends of the optocoupler U1 and the optocoupler U2 can be controlled to be simultaneously switched on or switched off according to the high or low of the control level, the current flow in any direction between the output end OA and the output end OK is allowed or forbidden, and the whole output circuit is equal to the output form of a common PLC relay.

The invention realizes multiple control functions of forward direct current on-off control, forward direct current on-off and follow current control, reverse direct current on-off and follow current control, alternating current on-off control and the like in the same hardware component through different control levels. The multifunctional output control circuit for the PLC can comprehensively replace three fixed output control circuit forms of transistor output, bidirectional thyristor output and relay output of the existing PLC, and can realize the switching of different functional output forms through software, so that the PLC is more flexible and convenient to apply, and the defects of low relay control response speed and short service life can be effectively overcome.

The invention is not limited to PLC, but also can be applied to other control systems and integrated into a universal chip.

Drawings

Fig. 1 is an electrical schematic diagram of a PLC multifunction output control circuit.

Detailed Description

As shown in fig. 1, an embodiment of a multifunctional output control circuit for PLC is composed of a current limiting resistor R1, a current limiting resistor R2, an optocoupler U1, and an optocoupler U2; the current-limiting resistor R1 is connected in series with the input end of the optocoupler U1 and is respectively connected to the control end EA and the common end COM; the current limiting resistor R2 is connected in series with the input end of the optocoupler U2 and is respectively connected to the control end EK and the common end COM; the output ends of the optical coupler U1 and the optical coupler U2 are connected in anti-parallel and are respectively connected to the output end OA and the output end OK.

When the control end EK is in long connection with the common end COM, no current passes through the input end of the optocoupler U2, the output end of the optocoupler U2 is always in an off state, and the control level of the control end EA is high or low at the moment, so that the current at the input end of the optocoupler U1 can be changed, the on or off of the output end of the optocoupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, and the whole output control circuit is equal to a common PLC transistor collector open-circuit forward output control.

When the control end EK is connected with a high level for a long time, the output end of the optical coupler U2 is always in a conducting state, the control level of the control end EA is high or low, the current at the input end of the optical coupler U1 can be changed, so that the on or off of the output end of the optical coupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, meanwhile, the conduction of the output end of the optical coupler U2 can provide the follow current flowing from the output end OK to the output end OA, and the whole output circuit is equal to a forward output control circuit of a common PLC transistor collector.

When the control end EA is in long connection with the common end COM, no current passes through the input end of the optocoupler U1, the output end of the optocoupler U1 is always in an off state, and the control level of the control end EK is high or low at the moment, so that the current at the input end of the optocoupler U2 can be changed, the on or off of the output end of the optocoupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, and the whole output control circuit is equal to a common PLC transistor collector open-circuit reverse output.

When the control end EA is connected with a high level for a long time, the output end of the optical coupler U1 is always in a conducting state, the control level of the control end EK is high or low, the current at the input end of the optical coupler U2 can be changed, the on or off of the output end of the optical coupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, meanwhile, the conduction of the output end of the optical coupler U1 can provide the follow current flowing from the output end OA to the output end OK, and the whole output circuit is equal to a reverse output control circuit of a common PLC transistor collector open.

When the same control level is sent to the control end EA and the control end EK, the output ends of the optocoupler U1 and the optocoupler U2 can be controlled to be simultaneously switched on or switched off according to the high or low of the control level, the current flow in any direction between the output end OA and the output end OK is allowed or forbidden, and the whole output circuit is equal to the output form of a common PLC relay.

Claims

1. A multifunctional output control circuit for PLC is composed of a current limiting resistor R1, a current limiting resistor R2, an optocoupler U1 and an optocoupler U2; the current-limiting resistor R1 is connected in series with the input end of the optocoupler U1 and is respectively connected to the control end EA and the common end COM; the current limiting resistor R2 is connected in series with the input end of the optocoupler U2 and is respectively connected to the control end EK and the common end COM; the output ends of the optical coupler U1 and the optical coupler U2 are connected in an anti-parallel mode and are respectively connected to the output end OA and the output end OK; when the control end EK is in long connection with the common end COM, no current passes through the input end of the optocoupler U2, the output end of the optocoupler U2 is always in an off state, and the control level of the control end EA is high or low at the moment, so that the current at the input end of the optocoupler U1 can be changed, the on or off of the output end of the optocoupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, and the whole output control circuit is equal to a common PLC transistor collector open-circuit forward output control; when the control end EK is connected with a high level for a long time, the output end of the optical coupler U2 is always in a conducting state, the control level of the control end EA is high or low, the current at the input end of the optical coupler U1 can be changed, so that the on or off of the output end of the optical coupler U1 is controlled, the current can be allowed or forbidden to flow from the output end OA to the output end OK, meanwhile, the conduction of the output end of the optical coupler U2 can provide the follow current flowing from the output end OK to the output end OA, and the whole output circuit is equal to a normal forward output control circuit of a PLC transistor collector; when the control end EA is in long connection with the common end COM, no current passes through the input end of the optocoupler U1, the output end of the optocoupler U1 is always in an off state, and the control level of the control end EK is high or low at the moment, so that the current at the input end of the optocoupler U2 can be changed, the on or off of the output end of the optocoupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, and the whole output control circuit is equal to a common PLC transistor collector open-circuit reverse output; when the control end EA is connected with a high level for a long time, the output end of the optical coupler U1 is always in a conducting state, the control level of the control end EK is high or low, the current at the input end of the optical coupler U2 can be changed, so that the on or off of the output end of the optical coupler U2 is controlled, the current can be allowed or forbidden to flow from the output end OK to the output end OA, meanwhile, the conduction of the output end of the optical coupler U1 can provide the follow current flowing from the output end OA to the output end OK, and the whole output circuit is equal to a reverse output control circuit of a common PLC transistor; when the same control level is sent to the control end EA and the control end EK, the output ends of the optocoupler U1 and the optocoupler U2 can be controlled to be simultaneously switched on or switched off according to the high or low of the control level, the current flow in any direction between the output end OA and the output end OK is allowed or forbidden, and the whole output circuit is equal to the output form of a common PLC relay.