Method for connecting two-wire system instrument into three-wire system or four-wire system
By adding an active signal isolator between the two-wire instrument and the original system, the signal of the two-wire instrument is converted into a signal suitable for the three-wire or four-wire system, the problem of changing or replacing the control template in the existing technology is solved, and the wide application of two-wire instruments and the stable operation of the PLC system is achieved.
Patent Information
- Application Number
- CN202411933194.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-04-29
AI Technical Summary
When the prior art connects the two-wire instrument to a three-wire or four-wire system, the control template needs to be changed or replaced, resulting in the PLC system being shut down when downloading the hardware, which poses the risk of download failure and the equipment being out of control.
By adding an active signal isolator between the two-wire instrument and the original system, the signal isolator power is matched with the original system, and the signal isolator is used to convert the signal of the two-wire instrument into a signal suitable for the three-wire or four-wire system, avoiding changing or replacing the control template.
It has realized that the two-wire instrument is successfully connected to the three-wire or four-wire PLC template without changing the control template settings, which expands the scope of use of the instrument, reduces labor costs, and avoids the risk of download failure and equipment out of control.
Smart Images
Figure CN119902462A_ABST
Abstract
Description
Technical Field
[0001] This patent application belongs to the field of equipment control technology, and more specifically, it relates to a method for connecting a two-wire instrument to a three-wire or four-wire system without replacing or modifying the control template settings, so as to expand the scope of use of the two-wire instrument. Background Art
[0002] In the production process, it is often necessary to connect a two-wire instrument to a three-wire or four-wire system. The conventional method is to change the template hardware settings or replace the control template and re-download it to the PLC system. There are certain risks in doing so. As we all know, the PLC system is in a shutdown state during the hardware download process, and the equipment operation cannot be controlled. There is also a risk of download failure. Once a failure occurs, the equipment will be out of control for a long time, which is unbearable for enterprises. Summary of the invention
[0003] The technical problem to be solved by the present invention is to provide a method for connecting a two-wire instrument to a three-wire or four-wire system, which can ensure that there is no need to replace the template or modify the PLC hardware settings when the two-wire instrument is connected to the three-wire or four-wire system, thereby avoiding the risks caused by downloading hardware.
[0004] In order to solve the above problems, the technical solution adopted by the present invention is: The method of connecting a two-wire instrument to a three-wire or four-wire system comprises the following steps: S1. Add a signal isolator between the two-wire instrument and the original system. The power supply of the signal isolator should match the voltage provided by the original system. The signal isolator is an active signal isolator. S2. The original system power supply "24V+" is connected to the "power +" input terminal of the signal isolator, the original system power supply "0V" is connected to the "power -" input terminal of the signal isolator, and the two-wire instrument is connected to the two-wire signal input terminal of the signal isolator; S3, determine whether the template in the original system is set to a four-wire system or a three-wire system. If it is a four-wire system, execute S4; if it is a three-wire system, execute S5; S4, the two-wire output signal of the signal isolator is connected to the signal input terminal of the four-wire template; S5. The two-wire signal isolation output terminal "OUT+" of the signal isolator is connected to the positive pole "I+" of the signal input terminal of the three-wire template. The two-wire signal isolation output terminal "OUT-" of the signal isolator is connected together with the "power supply -" input terminal of the signal isolator to the "0V" of the three-wire template.
[0005] Furthermore, the active signal isolator is a current signal isolator or a voltage signal isolator.
[0006] Furthermore, the terminals (power input / output terminals, two-wire signal input / output terminals) of the active signal isolator are plug-and-play terminals.
[0007] Furthermore, in S1, the original system is a PLC, and the voltage provided by the signal isolator power supply and the PLC template are both 24V.
[0008] Furthermore, the two-wire instrument includes, but is not limited to, one or more of a thermometer, a liquid level meter, an electromagnetic flow meter, a pressure meter, and a mass flow meter.
[0009] Furthermore, the template in the PLC is a Siemens template or a Japanese Yaskawa template.
[0010] Due to the adoption of the above technical solution, the beneficial effects achieved by the present invention are: This method is easy to install and has low labor costs. It can be effectively connected to a three-wire or four-wire PLC template without changing the control template settings, greatly expanding the use of two-wire instruments and improving the application occasions of two-wire instruments. It overcomes the drawbacks of the PLC system in the process of downloading hardware, eliminates the risk of download failure and the problem of equipment being out of control for a long time, and can achieve greater benefits with smaller adjustments, so it is highly popularizable and applicable. BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Figure 1 This is a schematic diagram of an embodiment of a four-wire PLC template in the present invention; Figure 2 It is a schematic diagram of an embodiment of a three-wire PLC template in the present invention. DETAILED DESCRIPTION
[0012] The present invention is further described in detail below with reference to the embodiments.
[0013] The method of connecting a two-wire instrument to a three-wire or four-wire system comprises the following steps: S1. Add a signal isolator between the two-wire instrument and the original system. The signal isolator selected in this embodiment is an active signal isolator, because the passive signal isolator cannot provide power to the two-wire instrument and cannot make the two-wire instrument work, so an active signal isolator must be used. The active signal isolator can be a current signal isolator or a voltage signal isolator. The power supply of the signal isolator matches the voltage provided by the original system, for example, the power supply of the signal isolator and the voltage provided by the PLC template are both 24V; the two-wire instrument includes but is not limited to one or more of a thermometer, a liquid level meter, an electromagnetic flowmeter, a pressure gauge, and a mass flowmeter, and can also be other two-wire instruments. The template selected in the PLC is a Siemens template or a Japanese Yaskawa template, or other adapter templates.
[0014] S2. The original system power supply "24V+" is connected to the "power +" input terminal of the signal isolator, the original system power supply "0V" is connected to the "power -" input terminal of the signal isolator, and the two-wire instrument is connected to the two-wire signal input terminal of the signal isolator; S3, determine whether the template in the original system is set to a four-wire system or a three-wire system. If it is a four-wire system, execute S4; if it is a three-wire system, execute S5; S4, the two-wire output signal of the signal isolator is connected to the signal input terminal of the four-wire template; S5. The two-wire signal isolation output terminal "OUT+" of the signal isolator is connected to the positive pole "I+" of the signal input terminal of the three-wire template. The two-wire signal isolation output terminal "OUT-" of the signal isolator is connected to the negative pole of the "power supply -" input terminal of the signal isolator and connected to the "0V" of the template.
[0015] In order to facilitate quick wiring, the terminals of the active signal isolator (power input / output terminals, two-wire signal input / output terminals) are plug-and-play terminals.
[0016] The following example illustrates this.
[0017] like Figure 1 , it is a four-wire PLC template. The power + and power - of the signal isolator are respectively connected to the 24V and 0V of the four-wire PLC template; the IN+ and IN- of the signal isolator are respectively connected to the I+ and I- of the two-wire instrument; the OUT+ and OUT- of the signal isolator are respectively connected to the I+ and I- of the four-wire PLC template.
[0018] like Figure 2 It is a three-wire PLC template. The power + and power - of the signal isolator are respectively connected to the 24V and 0V of the three-wire PLC template; the IN+ and IN- of the signal isolator are respectively connected to the I+ and I- of the two-wire instrument; the OUT+ and OUT- of the signal isolator are respectively connected to the I+ and 0V of the three-wire PLC template.
[0019] As can be seen from the above, this method is simple to install and has low labor costs. Without changing the control template settings, it can be effectively connected to the three-wire or four-wire PLC template, greatly expanding the use of two-wire instruments and improving the application occasions of two-wire instruments. It also overcomes the drawbacks of the PLC system in the process of downloading hardware, eliminates the risk of download failure and the problem of equipment being out of control for a long time, and obtains greater benefits with smaller adjustments, and its promotion and application is extremely high.
Claims
1. A method for connecting a two-wire instrument to a three-wire or four-wire system, characterized in that The steps include: S1. Add a signal isolator between the two-wire instrument and the original system. The power supply of the signal isolator matches the voltage provided by the original system. The signal isolator is an active signal isolator. S2. The power supply "24V+" of the original system is connected to the "power+" input terminal of the signal isolator, the power supply "0V" of the original system is connected to the "power-" input terminal of the signal isolator, and the two-wire instrument is connected to the two-wire signal input terminal of the signal isolator; S3, determine whether the template in the original system is set to a four-wire system or a three-wire system. If it is a four-wire system, execute S4; if it is a three-wire system, execute S5; S4, the two-wire output signal of the signal isolator is connected to the signal input terminal of the four-wire template; S5. The two-wire signal isolation output terminal "OUT+" of the signal isolator is connected to the positive pole "I+" of the signal input terminal of the three-wire template. The two-wire signal isolation output terminal "OUT-" of the signal isolator is connected together with the "power supply -" input terminal of the signal isolator and connected to the "0V" of the three-wire template.
2. The method for connecting a two-wire instrument to a three-wire or four-wire system according to claim 1, characterized in that: Active signal isolators are either current signal isolators or voltage signal isolators.
3. The method for connecting a two-wire instrument to a three-wire or four-wire system according to claim 2, characterized in that: The terminals of the active signal isolator are plug-and-play terminals.
4. The method for connecting a two-wire instrument to a three-wire or four-wire system according to claim 1, characterized in that: In S1, the original system is PLC.
5. The method for connecting a two-wire instrument to a three-wire or four-wire system according to claim 4, characterized in that: The template in the PLC is a Siemens template or a Japanese Yaskawa template.
6. The method for connecting a two-wire instrument to a three-wire or four-wire system according to any one of claims 1 to 5, characterized in that: Two-wire instruments include, but are not limited to, one or more of a thermometer, a liquid level meter, an electromagnetic flow meter, a pressure meter, and a mass flow meter.