TWI812467B - Pin detection system for providing circuit switching by circuit conversion card and method thereof - Google Patents

Abstract

A pin detection system for providing circuit switching by circuit conversion card and a method thereof are provided. Multiplexer on circuit conversion card is enabled according to switch signal by circuit conversion card. Detection signal input pin in enabled multiplexer and detection signal output pin in enabled multiplexer are connected according to switch signal. Detection signal is provided to pin to be detected by circuit switching. Therefore, the efficiency of multiplexer is enabled according to switch signal and circuit switch pin detection through detection signal input pin in enabled multiplexer and detection signal output pin in enabled multiplexer are connected according to switch signal may be achieved.

Description

Pin detection system and method for providing line switching through circuit conversion card

A pin detection system and method thereof, in particular, a line switching pin detection system that realizes the enablement of a multiplexer and the conduction of the multiplexer detection signal input pin and the detection signal output pin based on the switching signal. and methods.

Detecting the electronic components on the circuit board and the pins of the connection interface can effectively improve the yield of circuit board production. Different circuit boards use the same connection interface and the electronic components connected to the pins may be different. Therefore, even if the same connection interface is used for different circuit boards, the same adapter circuit board cannot be used to achieve the purpose of detection.

In addition, since the connection interface of the adapter circuit board is the same, an incorrect adapter circuit board may be used during the detection process, which will also cause the electronic components on the circuit board and the pins of the connection interface to be damaged. Wrong detection results are produced during detection.

In summary, it can be seen that in the prior art, there has been a long-standing problem in the prior art that for different circuit boards with the same connection interface, it is still necessary to develop an adapter circuit board for testing, which leads to increased testing costs and the adapter circuit board is prone to misuse. Therefore, It is necessary to propose improved technical means to solve this problem.

In view of the problem in the previous technology that for different circuit boards with the same connection interface, it is still necessary to design an adapter circuit board for testing, which leads to an increase in testing costs and the easy misuse of the adapter circuit board. The present invention discloses a circuit conversion card through A pin detection system for line switching and a method thereof are provided, wherein: the pin detection system disclosed in the present invention provides a pin detection system for line switching through a circuit conversion card, which includes: a detection device, a circuit conversion card and a circuit board to be tested.

The detection device has a connection interface, the detection device provides a switching signal through a switching signal pin of the connection interface, and the detection device selects at least one detection signal pin in the connection interface according to the switching signal to provide a detection signal.

The circuit conversion card has a conversion card connection interface, at least one multiplexer and a conversion card slot, a switching signal slot pin and a switching signal pin of the conversion card slot, and at least one switching signal input of the multiplexer. The pins form electrical connections, and at least one detection signal input slot pin in the conversion card slot is respectively connected to at least one detection signal input pin in the connection interface and at least one detection signal input pin in at least one multiplexer. The bits are electrically connected, one of the at least one multiplexers is enabled according to the switching signal, and at least one detection signal input pin of the enabled multiplexer is connected to the enabled multiplexer according to the switching signal. At least one detection signal output pin in the user is connected to each other, at least one detection signal output pin in at least one multiplexer forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface, and the detection signal respectively through at least one detection signal input slot pin in the conversion card slot, at least one detection signal input pin in the enabled multiplexer, and at least one detection signal in the enabled multiplexer The output pin and at least one detection signal interface pin in the conversion card connection interface.

The circuit board to be tested has at least one slot to be tested, and at least one detection signal slot pin in the slot to be tested forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface. At least one detection signal slot pin obtains a detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection.

The pin detection method for providing line switching through a circuit switching card disclosed in the present invention includes the following steps: first, the detection device has a connection interface; then, the detection device provides a switching signal through the switching signal pin of the connection interface; then, detecting The device selects at least one detection signal pin in the connection interface according to the switching signal to provide the detection signal; then, the circuit conversion card has a conversion card connection interface, at least one multiplexer and a conversion card slot; then, the conversion card slot The switching signal slot pin is electrically connected to the switching signal pin and the switching signal input pin of at least one multiplexer; then, at least one detection signal input slot pin in the conversion card slot is connected to the switching signal input pin respectively. At least one detection signal pin in the connection interface and at least one detection signal input pin in at least one multiplexer form an electrical connection; then, one of the at least one multiplexer is enabled according to the switching signal and According to the switching signal, at least one detection signal input pin in the enabled multiplexer and at least one detection signal output pin in the enabled multiplexer are connected to each other; then, at least one multiplexer At least one detection signal output pin in the device is electrically connected to at least one detection signal interface pin in the conversion card connection interface; then, the detection signals pass through at least one detection signal input slot pin in the conversion card slot, At least one detection signal input pin in the enabled multiplexer, at least one detection signal output pin in the enabled multiplexer, and at least one detection signal interface pin in the conversion card connection interface; then , the circuit board to be tested has at least one slot to be tested; then, at least one detection signal slot pin in the slot to be detected forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface; finally, At least one detection signal slot pin in the slot to be detected obtains a detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection.

The system and method disclosed by the present invention are as above. The difference between the system and the prior art is that the circuit conversion card enables the multiplexer in the circuit conversion card through the switching signal, and detects the enabled multiplexer based on the switching signal. The signal input pin and the detection signal output pin are connected to each other, thereby realizing circuit switching to provide the detection signal to the pin to be detected.

Through the above technical means, the present invention can achieve the technical effect of enabling the multiplexer and detecting the line switching pin of the multiplexer detection signal input pin and the detection signal output pin of the multiplexer based on the switching signal.

10:Detection device

11:Connection interface

111:Switch signal pin

112: First detection signal pin

113: Second detection signal pin

20:Circuit conversion card

21: Conversion card connection interface

22:Multiplexer

221: First multiplexer

2211: Switch signal input pin

2212: First detection signal input pin

2214: The third detection signal input pin

2216: First detection signal output pin

2217: Second detection signal output pin

2218: The third detection signal output pin

2219: The fourth detection signal output pin

222: Second multiplexer

2221: Switch signal input pin

2222: First detection signal input pin

2224: The third detection signal input pin

2227: Second detection signal output pin

2229: The fourth detection signal output pin

23: Conversion card slot

231: Switch signal slot pin position

232: First detection signal input slot pin

233: Second detection signal input slot pin

30: Circuit board to be tested

31: Slot to be detected

311: The first slot to be detected

312: The second slot to be detected

3112: Second detection signal slot pin

3114: The fourth detection signal slot pin

33: Controllable chip

Step 101: Detect that the device has a connection interface

Step 102: The detection device provides a switching signal through the switching signal pin of the connection interface

Step 103: The detection device selects at least one detection signal pin in the connection interface according to the switching signal to provide a detection signal.

Step 104: The circuit conversion card has a conversion card connection interface, at least one multiplexer and a conversion card slot.

Step 105: The switching signal slot pin of the conversion card slot is electrically connected to the switching signal pin and the switching signal input pin of at least one multiplexer.

Step 106: At least one detection signal input slot pin in the conversion card slot forms an electrical connection with at least one detection signal input pin in the connection interface and at least one detection signal input pin in at least one multiplexer. connect

Step 107: One of the at least one multiplexers is enabled based on the switching signal, and at least one detection signal of the enabled multiplexer is input to a pin of the enabled multiplexer based on the switching signal. At least one detection signal output pin of

Step 108: At least one detection signal output pin in the enabled multiplexer forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface.

Step 109: The detection signal passes through at least one detection signal input slot pin in the conversion card slot, at least one detection signal input pin in the enabled multiplexer, and in the enabled multiplexer. At least one detection signal output pin and at least one detection signal interface pin in the conversion card connection interface

Step 110: The circuit board to be tested has at least one slot to be tested

Step 111: At least one detection signal slot pin in the slot to be detected forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface.

Step 112: At least one detection signal slot pin in the slot to be detected obtains a detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection.

Figure 1 is a system block diagram of a pin detection system for providing line switching through a circuit conversion card according to the present invention.

Figure 2 is a schematic diagram of the connection interface pins for providing pin detection of line switching through a circuit conversion card according to the present invention.

Figure 3 is a schematic diagram of the pin connection of the conversion card connection interface, multiplexer and conversion card slot in the circuit conversion card that provides pin detection of line switching through the circuit conversion card according to the present invention.

Figure 4 is a schematic diagram of the socket pins to be detected that provide pin detection for line switching through a circuit conversion card according to the present invention.

Figures 5A and 5B are schematic diagrams of pin conduction of a multiplexer that provides pin detection for line switching through a circuit conversion card according to the present invention.

Figure 6A and Figure 6B are schematic diagrams of a circuit board to be tested that provides pin detection for line switching through a circuit conversion card according to the present invention.

Figures 7A and 7B illustrate a flow chart of a pin detection method for circuit switching provided through a circuit conversion card according to the present invention.

The embodiments of the present invention will be described in detail below with reference to the drawings and examples, so that the implementation process of how to apply technical means to solve technical problems and achieve technical effects of the present invention can be fully understood and implemented accordingly.

The following will first describe the pin detection system for providing line switching through a circuit conversion card disclosed in the present invention, and please refer to "Figure 1". "Figure 1" illustrates the circuit switching provided through a circuit conversion card according to the present invention. System block diagram of the pin detection system.

The pin detection system disclosed in the present invention provides line switching through a circuit conversion card, which includes: a detection device 10, a circuit conversion card 20 and a circuit board to be tested 30.

The detection device 10 has a connection interface 11. The circuit conversion card 20 has a conversion card connection interface 21, at least one multiplexer 22 and a conversion card slot 23. The connection interface 11 and the conversion card slot 23 form an electrical connection to be tested. The circuit board 30 has at least one slot 31 to be detected, and one of the at least one slot 31 to be detected is electrically connected to the conversion card connection interface 21 .

Please refer to "Figure 2". "Figure 2" is a schematic diagram of the connection interface pins for providing pin detection of line switching through the circuit conversion card of the present invention.

The detection device 10 provides a switching signal through the switching signal pin 111 of the connection interface 11, and the detection device 10 selects the first detection signal pin 112 and the second detection signal pin 113 in the connection interface 11 according to the switching signal to provide the detection signal.

Please refer to "Figure 3". "Figure 3" illustrates the conversion card connection interface, multiplexer and conversion card plug-in of the circuit conversion card that provides pin detection of line switching through the circuit conversion card according to the present invention. Slot pin connection diagram.

The switching signal slot pin 231 and the switching signal pin 111 of the conversion card slot 23 (please refer to "Figure 2"), and the switching signal input pin 2211 and the second multiplexer 221 of the first multiplexer 221. The switching signal input pin 2221 of the multiplexer 222 forms an electrical connection.

The first detection signal input slot pin 232 in the conversion card slot 23 is respectively connected with the first detection signal pin 112 (please refer to "Figure 2") in the connection interface 11 (please refer to "Figure 2") shown) and the first detection signal input pin 2212 of the first multiplexer 221 is electrically connected to the first detection signal input pin 2222 of the second multiplexer 222 .

The second detection signal input slot pin 233 in the conversion card slot 23 is respectively connected with the second detection signal pin 113 in the connection interface 11 (please refer to "Figure 2") and the first multiplexer The third detection signal input pin 2214 of the second multiplexer 221 is electrically connected to the third detection signal input pin 2224 of the second multiplexer 222 .

In the embodiment, the first multiplexer 221 is enabled according to the switching signal and the first detection signal input pin 2212 of the enabled first multiplexer 221 is connected to the enabled first multiplexer 221 according to the switching signal. The second detection signal output pins 2217 in the multiplexer 221 are connected to each other; the first multiplexer 221 is enabled according to the switching signal and the third detection signal in the first multiplexer 221 is enabled according to the switching signal. signal The input pin 2214 is connected to the fourth detection signal output pin 2219 of the enabled first multiplexer 221.

In the embodiment, the second detection signal output pin 2217 of the first multiplexer 221 forms an electrical connection with the second detection signal interface pin 212 of the conversion card connection interface 21. The first multiplexer 221 The fourth detection signal output pin 2219 in the conversion card connection interface 21 is connected to the fourth detection signal interface pin 214 in the conversion card connection interface 21; the second detection signal output pin 2227 in the second multiplexer 222 is connected to the conversion card connection interface 21. The two detection signal interface pins 212 are electrically connected, and the fourth detection signal output pin 2229 of the second multiplexer 222 is electrically connected to the fourth detection signal interface pin 214 of the conversion card connection interface 21 .

Please refer to "Figure 4". "Figure 4" is a schematic diagram of the socket pins to be detected that provide pin detection for line switching through the circuit conversion card of the present invention.

In the embodiment, the circuit board 30 to be tested has a first slot 311 to be tested and a second slot 312 to be tested. The second detection signal slot pin 3112 in the first slot 311 is connected to the conversion card connection interface. 21 (please refer to the “Figure 3”), the second detection signal interface pin 212 (please refer to the “Figure 3”) forms an electrical connection, and the fourth detection signal in the first slot 311 to be detected The slot pin 3114 forms an electrical connection with the fourth detection signal interface pin 214 (please refer to "Figure 3") in the conversion card connection interface 21. It is worth noting that the first slot 311 to be detected and the fourth detection signal interface pin 214 are electrically connected. The two slots 312 to be detected can be of the same slot type, and the first slot 311 and the second slot 312 to be detected can also be of different slot types, so the conversion card connection interface 21 is electrically connected to The slot types of the first slot to be detected 311 or the second slot to be detected 312 match each other.

The detection device 10 provides a detection signal through the first detection signal pin 112. The detection signal passes through the first detection signal input slot pin 232 in the conversion card slot 23 and the enabled first multi-channel The first detection signal input pin 2212 in the multiplexer 221, the second detection signal output pin 2217 in the enabled first multiplexer 221, and the second detection signal interface pin in the conversion card connection interface 21 212. The second detection signal slot pin 3112 in the circuit board 30 to be tested obtains a detection signal from the second detection signal interface pin 212 in the conversion card connection interface 21 to perform pin detection.

The detection device 10 provides a detection signal through the second detection signal pin 113. The detection signal passes through the second detection signal input slot pin 233 in the conversion card slot 23 and the enabled first multiplexer 221 respectively. The third detection signal input pin 2214, the fourth detection signal output pin 2219 in the enabled first multiplexer 221 and the fourth detection signal interface pin 214 in the conversion card connection interface 21, circuit board to be tested The fourth detection signal slot pin 3114 in 30 obtains a detection signal from the fourth detection signal interface pin 214 in the conversion card connection interface 21 to perform pin detection.

Please refer to "Figure 5A" and "Figure 5B". "Figure 5A" and "Figure 5B" illustrate the multiplexer pins that provide pin detection for line switching through the circuit conversion card of the present invention. Bit conduction diagram.

In "Figure 5A", the first multiplexer 221 is enabled according to the first switching signal and the first detection signal input pin 2212 of the first multiplexer 221 will be enabled according to the first switching signal. The second detection signal output pin 2217 of the enabled first multiplexer 221 is connected to each other; the first multiplexer 221 is enabled according to the first switching signal and will enable the third detection signal according to the first switching signal. The third detection signal input pin 2214 of a multiplexer 221 and the fourth detection signal output pin 2219 of the enabled first multiplexer 221 are electrically connected to each other.

In "Figure 5B", the first multiplexer 221 is enabled according to the second switching signal and the first detection signal input pin 2212 of the first multiplexer 221 will be enabled according to the second switching signal. The first detection signal output pin 2216 of the enabled first multiplexer 221 is connected to each other; The multiplexer 221 is enabled according to the second switching signal and the third detection signal input pin 2214 of the enabled first multiplexer 221 is connected to the enabled first multiplexer according to the second switching signal. The third detection signal output pins 2218 in 221 are connected to each other, thereby realizing circuit switching to provide detection signals to the pins that need to be detected.

Please refer to "Figure 6A" and "Figure 6B". "Figure 6A" and "Figure 6B" are schematic diagrams of a circuit board to be tested that provides pin detection for line switching through a circuit conversion card according to the present invention.

In "Figure 6A", the first slot 311 of the circuit board to be tested 30 and the second slot 312 of the circuit board to be tested 30 can be electrically connected to each other through differential lines. The circuit to be tested The first slot 311 to be tested and the second slot 312 of the circuit board 30 to be tested can also be independent. This is only an example and does not limit the application scope of the present invention.

In "Figure 6B", the circuit board to be tested 30 further includes a controllable chip 33. The first socket to be tested 311 of the circuit board to be tested 30 and the second socket to be tested 312 of the circuit board to be tested 30 are respectively connected through differential The circuit is electrically connected to the controllable chip 33. In addition, the first slot 311 of the circuit board to be tested 30 or the second slot 312 of the circuit board to be tested 30 can be connected to the control chip 33 through differential lines alone. The electrical connection formed by the controllable chip 33 is only used as an example and does not limit the application scope of the present invention.

Next, the operation method of the present invention will be described below, and please refer to "Figure 7A" and "Figure 7B" at the same time. "Figure 7A" and "Figure 7B" illustrate the circuit conversion card provided by the present invention. Method flow chart of the pin detection method for line switching.

The pin detection method for providing line switching through a circuit switching card disclosed in the present invention includes the following steps: first, the detection device has a connection interface (step 101); then, the detection device provides a switching signal through the switching signal pin of the connection interface (Step 102); Then, the detection device selects at least one detection signal pin in the connection interface according to the switching signal to provide a detection signal (Step 103); Then, the circuit conversion card has a conversion card connection interface, at least one multiplexer and the conversion card slot (step 104); then, the switching signal slot pin of the conversion card slot forms an electrical connection with the switching signal pin and the switching signal input pin of at least one multiplexer (step 105) ; Then, at least one detection signal input slot pin in the conversion card slot forms electrical connections with at least one detection signal input pin in the connection interface and at least one detection signal input pin in at least one multiplexer. Connection (step 106); then, one of the at least one multiplexers is enabled according to the switching signal and at least one detection signal input pin of the enabled multiplexer is connected to the enabled multiplexer according to the switching signal. At least one detection signal output pin in the multiplexer is connected to each other (step 107); then, at least one detection signal output pin in the enabled multiplexer is connected to at least one detection signal interface in the conversion card connection interface The pins are electrically connected (step 108); then, the detection signals pass through at least one detection signal input slot pin in the conversion card slot and at least one detection signal input pin in the enabled multiplexer. , at least one detection signal output pin in the enabled multiplexer and at least one detection signal interface pin in the conversion card connection interface (step 109); then, the circuit board to be tested has at least one slot to be tested ( Step 110); then, at least one detection signal slot pin in the slot to be detected forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface (step 111); finally, the detection signal slot pin in the slot to be detected is electrically connected. At least one detection signal slot pin obtains a detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection (step 112).

In summary, it can be seen that the difference between the present invention and the prior art is that the circuit conversion card enables the multiplexer in the circuit conversion card through the switching signal, and inputs the enabled multiplexer detection signal according to the switching signal. The pin and the detection signal output pin are connected to each other, thereby realizing circuit switching to provide the detection signal to the pin to be detected.

This technical means can solve the problem in the previous technology that for different circuit boards with the same connection interface, it is still necessary to design an adapter circuit board for testing, which leads to an increase in testing costs and the easy misuse of the adapter circuit board. The technical function of enabling the multiplexer and detecting the connection of the multiplexer detection signal input pin and the detection signal output pin based on the switching signal is achieved.

Although the embodiments disclosed in the present invention are as above, the described contents are not used to directly limit the patent protection scope of the present invention. Anyone with ordinary knowledge in the technical field to which the present invention belongs may make slight changes in the form and details of the implementation without departing from the spirit and scope of the disclosure of the present invention. The patent protection scope of the present invention must still be defined by the attached patent application scope.

10:Detection device

11:Connection interface

20:Circuit conversion card

21: Conversion card connection interface

22:Multiplexer

23: Conversion card slot

30: Circuit board to be tested

31: Slot to be detected

Claims (8)

A pin detection system that provides line switching through a circuit conversion card, which includes: a detection device with a connection interface, the detection device provides a switching signal through a switching signal pin of the connection interface, and the detection device The device selects at least one detection signal pin in the connection interface according to the switching signal to provide a detection signal; a circuit conversion card has a conversion card connection interface, at least one multiplexer and a conversion card slot, A switching signal slot pin of the conversion card slot is electrically connected to the switching signal pin and a switching signal input pin of the at least one multiplexer. The at least one detection signal input slot pin is electrically connected to the at least one detection signal input pin in the connection interface and the at least one detection signal input pin in the at least one multiplexer, One of the at least one multiplexers is enabled according to the switching signal and the at least one detection signal input pin in the multiplexer that will be enabled according to the switching signal is connected to the enabled multiplexer. At least one detection signal output pin in the multiplexer is connected to each other, and the at least one detection signal output pin in the at least one multiplexer is connected to at least one detection signal interface pin in the conversion card connection interface. The bits are electrically connected, and the detection signals pass through the at least one detection signal input slot pin in the conversion card slot and the at least one detection signal input pin in the enabled multiplexer. bit, at least one detection signal output pin in the enabled multiplexer and at least one detection signal interface pin in the conversion card connection interface; and A circuit board to be tested has at least one slot to be tested, and at least one detection signal slot pin in the slot to be tested forms an electrical connection with at least one detection signal interface pin in the conversion card connection interface, At least one detection signal slot pin in the slot to be detected obtains the detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection. The pin detection system for providing line switching through a circuit conversion card as described in claim 1, wherein the at least one slot to be detected is of the same slot type, and the at least one slot to be detected is partially the same and partially different. The same slot type, or the at least one slot to be detected is a different slot type. The pin detection system for providing line switching through a circuit conversion card as described in claim 1, wherein the circuit board to be tested electrically connects the at least one slot to be tested to each other through differential lines. The pin detection system for providing line switching through a circuit conversion card as described in claim 1, wherein the circuit board to be tested further includes a controllable chip, and the at least one slot to be detected is connected to the controllable chip through a differential line. The chip is electrically connected, or the at least one socket part to be detected is electrically connected to the controllable chip through a differential line. A pin detection method for providing line switching through a circuit conversion card, which includes the following steps: a detection device has a connection interface; the detection device provides a switching signal through a switching signal pin of the connection interface; The detection device selects at least one detection signal pin in the connection interface according to the switching signal to provide a detection signal; a circuit conversion card has a conversion card connection interface, at least one multiplexer and a conversion card plug-in slot; a switching signal slot pin of the conversion card slot forms an electrical connection with the switching signal pin and a switching signal input pin of the at least one multiplexer; the conversion card slot At least one detection signal input slot pin in the slot forms an electrical connection with the at least one detection signal input pin in the connection interface and at least one detection signal input pin in the at least one multiplexer. Connect; one of the at least one multiplexers is enabled according to the switching signal and the at least one detection signal input pin in the multiplexer that will be enabled according to the switching signal is connected to the enabling pin. At least one detection signal output pin in the multiplexer is connected to each other; the at least one detection signal output pin in the at least one multiplexer and at least one detection signal in the conversion card connection interface The interface pins form an electrical connection; the detection signals respectively pass through the at least one detection signal input slot pin in the conversion card slot and the at least one detection signal in the enabled multiplexer. Input pins, at least one detection signal output pin in the enabled multiplexer, and at least one detection signal interface pin in the conversion card connection interface; a circuit board to be tested has at least one slot to be tested; At least one detection signal slot pin in the slot to be detected is electrically connected to at least one detection signal interface pin in the conversion card connection interface; and at least one detection signal slot in the slot to be detected is electrically connected. The slot pin obtains the detection signal from at least one detection signal interface pin in the conversion card connection interface to perform pin detection. The pin detection method for providing line switching through a circuit conversion card as described in claim 5, wherein the at least one slot to be detected is of the same slot type, and the at least one slot to be detected is partially the same and partially different. The same slot type, or the at least one slot to be detected is a different slot type. As claimed in claim 5, the pin detection method for line switching is provided through a circuit conversion card, wherein the circuit board to be tested electrically connects the at least one slot to be tested to each other through differential lines. As claimed in claim 5, the pin detection method for line switching is provided through a circuit conversion card, wherein the circuit board to be tested further includes a controllable chip, and the at least one slot to be tested is connected to the controllable chip through a differential line. The chip is electrically connected, or the at least one socket part to be detected is electrically connected to the controllable chip through a differential line.

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