CN105759678A - Switching quantity output module of DCS - Google Patents

Abstract

The invention discloses a switching value output module of a DCS system, which includes a power supply, a CPU module, a power-on delay circuit, a communication circuit and a digital output channel circuit. The power supply is used to supply power to the entire switching value output module. The CPU module is used to communicate with the control station of the DCS system through the communication circuit, the CPU module is used to output control signals to the digital output channel circuit, and is used to control the digital output channel circuit to output switching signals to the field equipment. The power-on delay circuit is used to receive the reset signal and delay the power-on of the digital output channel circuit. It can record the state before reset, and the output state after reset can be kept consistent with that before reset.

Description

Switch output module of DCS system

technical field

The invention relates to the field of DCS control systems, in particular to a switch output module of the DCS system.

Background technique

In the DCS control system, the use of DO switch output modules is very popular. In the field, it is often encountered that due to some special circumstances, the module needs to be powered on for reset, such as the module is broken, and the module needs to be replaced online, or the power supply module is damaged in the application without power supply redundancy system, or the industrial voltage is too low for a period of time and the power supply The module stops working, waits for it to work again after it returns to normal, and so on. Because the moment the module is reset, in general, the output channel is faster than the CPU, that is to say, when the CPU has not completed the initialization, the output channel has already output value, making the output status uncertain after reset, resulting in chaos of the valves and other equipment controlled by it. action hazard. The traditional method is to wait until the condition permits and the controlled device jumps to allow the module reset operation. The disadvantage of the prior art is that in some important application occasions, the switch output module can only be replaced or reset when it is shut down for maintenance. Either remove the wires of all channels of the module and reconnect them after the operation is completed. In this way, the problem cannot be dealt with in time, or it is more complicated.

Contents of the invention

The purpose of the present invention is to provide a switch output module of the DCS system, which can record the state before reset, and the output state after reset can be kept consistent with that before reset.

The object of the present invention is achieved in this way: a switch output module of a DCS system includes a power supply, a CPU module, a power-on delay circuit, a communication circuit and a digital output channel circuit, and the power supply is used to supply the entire switch The output module supplies power, the CPU module is used to communicate with the control station of the DCS system through the communication circuit, the CPU module is used to output control signals to the digital output channel circuit, and is used to control the digital output channel circuit to output switching signals For the field device, the working state of the field device is controlled, and the power-on delay circuit is used to receive the reset signal and delay the power supply to the digital output channel circuit.

The power-on delay circuit includes a first switch tube Q1, a second switch tube VT13, and several resistors and capacitors. The base of the first switch tube Q1 is connected to one end of the tenth resistor R10, and the other end of the tenth resistor R10 respectively connected to one end of the 19th resistor R19, one end of the 19th capacitor C19 and the reset signal, the other end of the 19th resistor R19 is connected to the power supply VCC, the other end of the 19th capacitor C19 is grounded, and the first switching tube Q1 The emitter is connected to the power supply VCC, the collector of the first switching tube Q1 is respectively connected to the base of the second switching tube VT13, and one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded. The bases of the second switching tube VT13 are respectively connected to one end of the eighth resistor R8 and the negative pole of the 42nd capacitor C42, and the other end of the eighth resistor R8 and the positive pole of the 42nd capacitor C42 are connected to the power supply VCC, and the second switch The emitter of the tube VT13 is connected to the power supply VCC, and the collector of the second switching tube VT13 is connected to the power supply terminal of the digital output channel circuit.

A first isolation circuit is provided between the CPU module and the communication circuit.

A second isolation circuit is provided between the CPU module and the digital output channel circuit.

Due to the adoption of the above scheme, since the switch output module of the DCS system is provided with a power-on delay circuit, the power-on delay circuit is used to receive the reset signal and delay the power supply to the digital output channel circuit. When the switch output module of the DCS system is powered on and reset, the power-on delay circuit controls the digital output channel circuit to delay power on, so that the digital output channel circuit has no output during the reset period. When the switch output module of the DCS system is powered on After the reset is completed, the CPU module will send the corresponding value to the digital output channel circuit according to the output state before the reset. At this time, the channel control circuit will only be powered under the action of the delay circuit, so that the switching output module of the DCS system The output state value after reset is the same as the output state value before reset, avoiding the danger of random movement of valves and other equipment controlled by it.

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is the functional block diagram of switch quantity output module of the present invention;

FIG. 2 is a circuit diagram of the power-on delay circuit of the present invention.

detailed description

Referring to Fig. 1, a switch output module of a DCS system includes a power supply, a CPU module, a power-on delay circuit, a communication circuit and a digital output channel circuit, and the power supply is used to supply power to the entire switch output module, so The CPU module is used for communicating with the control station of the DCS system through the communication circuit, and receiving the control signal of the control station of the DCS system. A communication circuit is a circuit that communicates. Through it, the CPU can communicate with other smart products. Its core is the communication chip used, such as SP485 and so on. It is connected to the 485 bus outside and the isolation circuit on the other side. The CPU module is used to output control signals to the digital output channel circuit, and is used to control the digital output channel circuit to output switching signals to field devices. The CPU module can output corresponding signals according to the output state value before reset. The digital output channel circuit refers to the DO output signal channel of the digital output module, which can be a level output signal or an open-collector output signal, etc., and is used to output the digital signal to the scene. The power-on delay circuit is used to receive the reset signal, and delay the power-on of the digital output channel circuit. When the switching output module of the DCS system is powered on and reset, the power-on delay circuit controls the digital output channel circuit to delay power on, so that the digital output channel circuit has no output. When the switching output module of the DCS system is powered on and reset is completed , the CPU module will send corresponding signals to the digital output channel circuit according to the output state value before reset, so that the output state value of the switching output module of the DCS system after reset is the same as the output state value before reset, so as to avoid being controlled by it The danger of random movement of valves and other equipment. A first isolation circuit is provided between the CPU module and the communication circuit. A second isolation circuit is provided between the CPU module and the digital output channel circuit. The second isolation circuit is to isolate the control signal, the first isolation circuit is to isolate the communication signal, and the communication isolation is to isolate the interference signal on the communication line so that it cannot enter the core circuit. The control line isolation is to prevent the interference signal on the channel from entering the internal core circuit. Isolation is commonly used with optical isolation and magnetic isolation.

Referring to FIG. 2, the power-on delay circuit includes a first switching tube Q1, a second switching tube VT13, and several resistors and capacitors. The base of the first switching tube Q1 is connected to one end of the tenth resistor R10, and the tenth resistor The other end of R10 is respectively connected to one end of the 19th resistor R19, one end of the 19th capacitor C19 and the reset signal, the other end of the 19th resistor R19 is connected to the power supply VCC, the other end of the 19th capacitor C19 is grounded, and the first The emitter of the switching tube Q1 is connected to the power supply VCC, the collector of the first switching tube Q1 is respectively connected to the base of the second switching tube VT13 and one end of the ninth resistor R9, and the other end of the ninth resistor R9 is grounded , the base of the second switching tube VT13 is respectively connected to one end of the eighth resistor R8 and the negative pole of the 42nd capacitor C42, and the other end of the eighth resistor R8 and the positive pole of the 42nd capacitor C42 are connected to the power supply VCC, so The emitter of the second switching tube VT13 is connected to the power supply VCC, and the collector of the second switching tube VT13 is connected to the power terminal of the digital output channel circuit.

Referring to Figure 2, the reset signal RST (RST comes from the signal of the CPU reset circuit in the module) is introduced into the CPU and connected to R10 in the figure. This signal will turn on Q1 at the moment of power-on. As a result, there will be a level close to VCC on R9, which is the base level of VT13, which will keep VT13 off. In this way, P1 that supplies power to the channel will have no voltage, and the digital output channel circuit will have no output. on the contrary. After the RST reset is completed, Q1 will be turned off, VT13 will be turned on, and P1 will be powered on to supply power to the digital output channel circuit. At the same time, after the RST reset is completed, the CPU will read the output state value before the reset and send it to the digital output channel circuit, so that after the above process, the output value of the switch output module after reset will be the value before reset.

The present invention is not limited to the above-mentioned embodiments, and technical solutions with slight changes without departing from the principle and spirit of the technical solutions of the present invention shall fall within the protection scope of the present invention.

Claims (4)

1. the switching value output module of a DCS system, it is characterized in that: include power supply, CPU module, power on delay circuit, telecommunication circuit and digital quantity output channel circuit, described power supply is for powering to whole switching value output module, described CPU module is for carrying out communication by the control station of telecommunication circuit Yu DCS system, described CPU module is used for exporting control signal to digital output channel circuit, for controlling digital output channel circuit output switch amount signal, described power on delay circuit is used for accepting reset signal, postpone to be energized to digital output channel circuit.

null2. switching value output module according to claim 1，It is characterized in that: described power on delay circuit includes the first switching tube (Q1)、Second switch pipe (VT13) and some resistance、Electric capacity，The base stage of described first switching tube (Q1) is connected with one end of the 10th resistance (R10)，The other end of the 10th resistance (R10) respectively with one end of the 19th resistance (R19)、One end of 19th electric capacity (C19) and reset signal connect，The other end of the 19th resistance (R19) is connected with power supply (VCC)，The other end ground connection of the 19th electric capacity (C19)，The emitter stage of described first switching tube (Q1) is connected with power supply (VCC)，The colelctor electrode of described first switching tube (Q1) is respectively at the base stage with second switch pipe (VT13)、One end of 9th resistance (R9) connects，The other end ground connection of the 9th resistance (R9)，The base stage of described second switch pipe (VT13) respectively with one end of the 8th resistance (R8)、The negative pole of the 42nd electric capacity (C42) connects，The other end of the 8th resistance (R8)、The positive pole of the 42nd electric capacity (C42) is all connected with power supply (VCC)，The emitter stage of described second switch pipe (VT13) is connected with power supply (VCC)，The colelctor electrode of second switch pipe (VT13) is connected with the power end of digital output channel circuit.

3. switching value output module according to claim 1, it is characterised in that: it is provided with the first isolation circuit between described CPU module and telecommunication circuit.

4. switching value output module according to claim 1, it is characterised in that: it is provided with the second isolation circuit between described CPU module and digital output channel circuit.