CN212391790U

CN212391790U - Isolated RS232 data port changes converter of CAN bus

Info

Publication number: CN212391790U
Application number: CN202021098077.4U
Authority: CN
Inventors: 周建鹏; 龚元明; 吴长水
Original assignee: Shanghai University of Engineering Science
Current assignee: Shanghai Xinhui Electronics Co ltd
Priority date: 2020-06-15
Filing date: 2020-06-15
Publication date: 2021-01-22
Anticipated expiration: 2030-06-15

Abstract

The utility model relates to a converter of isolated RS232 data port commentaries on classics CAN bus, this converter include power supply circuit and microcontroller CPU, CAN interface circuit, isolated RS232 interface circuit who is connected with power supply circuit respectively, microcontroller CPU pass through asynchronous serial interface and isolated RS232 interface circuit and be connected to and be connected with CAN interface circuit through the CAN interface. The utility model provides a RS232 interface of isolation will have the instrument and meter of RS232 interface and outside industrial field network's CAN bus connection, realizes that data signal keeps apart and the power is kept apart. Compared with the prior art, the utility model discloses have can prevent ground loop current, the interference killing feature in adverse circumstances is strong, the size is little, the low power dissipation, the reliability is high.

Description

Isolated RS232 data port changes converter of CAN bus

Technical Field

The utility model belongs to the technical field of the instrument and meter technique and specifically relates to a converter of isolated RS232 data port commentaries on classics CAN bus is related to.

Background

In the prior art, a CAN interface circuit and an RS232 interface circuit connect an instrument with an RS232 interface with an industrial field network CAN bus to realize serial long-line transmission of test data.

Due to the fact that the non-isolated RS232 interface adopted by the instrument and the industrial field network have different ground potentials, the generation of ground loop current can be caused. In addition, high common mode voltages may occur due to the RS232 interface circuit not being isolated, thereby increasing distortion and error of the transmitted data.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing an isolated RS232 data port changes converter of CAN bus in order to overcome the defect that above-mentioned prior art exists.

The purpose of the utility model can be realized through the following technical scheme:

the converter comprises a power supply circuit, and a microcontroller CPU, a CAN interface circuit and an isolated RS232 interface circuit which are respectively connected with the power supply circuit, wherein the microcontroller CPU is connected with the CAN interface circuit through a CAN interface and is also connected with the isolated RS232 interface circuit through an asynchronous serial interface. The isolated RS232 interface circuit is connected with an instrument with an RS232 interface. The CAN interface circuit is connected with a CAN bus of an external industrial field network.

Preferably, the power circuit includes a power input socket, a power chip, a power input end filter capacitor, a power output end filter capacitor, a freewheeling diode, an energy storage inductor, a +12V power interface, a +5V power interface, and a PGND ground terminal, an IN power input end of the power chip is connected to a +12V power interface and a V + signal end of the power input socket, a power ground terminal GND is connected to the PGND ground terminal and a V-signal end of the power input socket, an SHDN turn-off control terminal is connected to the PGND ground terminal, an FB feedback terminal is connected to the +5V power interface, an SW output end is connected to the +5V power interface through the energy storage inductor, the power input end filter capacitor is connected IN parallel to an output end of the power input socket, and an anode of the power output end filter capacitor is connected to the +5V power interface, the negative pole is connected with the PGND grounding end, the positive pole of the freewheeling diode is connected with the PGND grounding end, the negative pole is connected between the SW output end of the power chip and the energy storage inductor, the +5V power interface is respectively connected with the microcontroller CPU, the CAN interface circuit and the isolated RS232 interface circuit, and the PGND grounding end is respectively connected with the grounding ends connected with the microcontroller CPU, the CAN interface circuit and the isolated RS232 interface circuit and grounded.

Preferably, the CAN interface circuit includes a CAN transceiver, a third filter capacitor, an impedance matching resistor, a CANH connector and a CANL connector, the CAN transceiver passes through a CAN interface of the microcontroller CPU and communicates with the microcontroller CPU, and is respectively connected with a CAN _ H signal line and a CAN _ L signal line of a CAN bus of an external industrial field network through the CANH connector and the CANL connector, a VCC power supply end of the CAN transceiver is connected with the +5V power supply interface, a GND ground end is connected with the PGND ground end, a pin # 1 and a pin # 2 of the third filter capacitor are respectively connected with a VCC signal end and a GND signal end of the CAN transceiver, and the impedance matching resistor is connected between the CANH connector and the CANL connector.

Preferably, the isolated RS232 interface circuit includes an isolated RS232 transceiver, a first decoupling capacitor, a second decoupling capacitor, a first filter capacitor, a second filter capacitor, a first charge pump capacitor, a second charge pump capacitor, an RS232 connection socket, and an isolated ground terminal, wherein a VCC power terminal and a GND ground terminal of the isolated RS232 transceiver are respectively connected to the +5V power interface and the PGND ground terminal of the power circuit, a ROUT receiver output signal terminal and a TIN transmitter input signal terminal of the isolated RS232 transceiver are connected to 1 asynchronous serial interface of the microcontroller CPU, a RIN receiver input signal terminal, a TOUT transmitter output signal terminal and a gno isolated ground terminal of the isolated RS232 transceiver U3 are respectively connected to a pin # 1, a pin # 2 and a pin # 3 of the RS232 connection socket, and a pin # 1 and a pin # 2 of the first decoupling capacitor are respectively connected to the power terminal of the isolated RS232 transceiver and the VCC power circuit The pin 1# and the pin 2# of the second decoupling capacitor are respectively connected with a VISO isolation power supply terminal and the isolation ground terminal of the isolated RS232 transceiver, the pin 1 and the pin 2 of the first filter capacitor are respectively connected with a VISO isolation power supply end and a V + power supply end of the isolation RS232 transceiver, the pin 1 and the pin 2 of the second filter capacitor are respectively connected with the V-power end of the isolated RS232 transceiver and the isolated grounding end, the pin 1 and the pin 2 of the first charge pump capacitor are respectively connected with the signal terminal C1+ and the signal terminal C1 of the isolated RS232 transceiver, the pin 1 and the pin 2 of the second charge pump capacitor are respectively connected with the signal terminal C2+ and the signal terminal C2 of the isolated RS232 transceiver, the isolation ground terminal is connected with the GNDISO isolation ground terminal of the isolation RS232 transceiver.

Preferably, the model of the power chip is MIC4680-5.0BM, the filter capacitor at the power input end is an electrolytic capacitor, the capacitance value and the withstand voltage value of the electrolytic capacitor are 100 μ F and 50V, respectively, the filter capacitor at the power output end is an electrolytic capacitor, the capacitance value and the withstand voltage value of the electrolytic capacitor are 47 μ F and 16V, the model of the freewheeling diode is 1N5819, and the inductance value of the energy storage inductor is 68 μ H.

Preferably, the type of the CAN transceiver is TLE6250GV33, the resistance of the impedance matching resistor is 120 Ω, and the capacitance and withstand voltage of the third filter capacitor are 0.1 μ F and 16V, respectively.

Preferably, the isolated RS232 transceiver is of a type ADM3251E, and capacitance values and withstand voltage values of the first decoupling capacitor, the second decoupling capacitor, the first filter capacitor, the second filter capacitor, the first charge pump capacitor and the second charge pump capacitor are all 1 μ F and 25V.

Preferably, the chip model of the microcontroller CPU is Infineon XC 2234L.

Compared with the prior art, the utility model has the advantages of it is following:

(1) the anti-interference capability and the anti-grounding loop current are strong. The utility model discloses an isolated RS232 transceiver CAN realize that data signal keeps apart and the power is kept apart between the instrument and meter that has the RS232 interface and industrial field network's CAN bus. Thus, not only can the ground loop current be prevented; and can prevent the interference of the high common mode voltage coupled to the RS232 cable under the severe environment from causing damage to the RS-232 transceiver and data transmission errors.

(2) Small size, low power consumption and high reliability. Conventional optocoupler isolation schemes have relatively high power consumption due to low conversion efficiency of the photoelectric conversion, slow response of the photodetector limits its speed, and aging issues limit its lifetime. The utility model discloses with miniature on-chip transformer and standard RS232 interface transceiver integrated in a chip, required components and parts quantity obviously reduces, has reduced the overall dimension and has reduced system cost, improved the reliability.

Drawings

To further clarify the above and other advantages and features of various embodiments of the present invention, a more particular description of various embodiments of the invention will be rendered by reference to the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. Also, the relative positions and sizes of the respective portions shown in the drawings are exemplary, and should not be understood as uniquely determining positional or dimensional relationships between the respective portions.

Fig. 1 is a schematic circuit diagram of the present invention;

fig. 2 is a circuit diagram of a power supply circuit of the present invention;

fig. 3 is a circuit diagram of the CAN interface circuit of the present invention;

fig. 4 is a circuit diagram of the isolated RS232 interface circuit of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall fall within the protection scope of the present invention.

Examples

The utility model discloses a circuit schematic is shown in fig. 1, a converter of isolated RS232 data port commentaries on classics CAN bus, and this converter includes power supply circuit 1, CAN interface circuit 3, isolated RS232 interface circuit 2 and microcontroller CPU.

As shown IN fig. 2, the power supply circuit 1 includes a power input socket J1, a power supply chip U1, a power input terminal filter capacitor C1, a power output terminal filter capacitor C2, a freewheeling diode D1, an energy storage inductor L1, a +12V power interface P0, a +5V power interface P1 and a PGND ground terminal P2, the power supply chip U1 is MIC4680-5.0BM, an IN power input terminal thereof is connected to the +12V power interface P0 and a V + signal terminal of the power input socket J1, a GND power ground terminal is connected to the PGND ground terminal P2 and a V-signal terminal of the power input socket J1, as a power ground of the whole circuit, a shutdown control terminal SHDN of the power supply chip U1 is connected to the PGND ground terminal P2, a feedback terminal thereof is connected to the FB +5V power interface P1, a power input terminal filter capacitor C1 is connected IN parallel to the output terminal J1, and a positive terminal of the power supply output terminal filter capacitor C2 is connected to the power input terminal P1V +1, the negative electrode of the energy storage inductor L1 is connected with a PGND grounding end P2, and a pin 1 and a pin 2 of the energy storage inductor L1 are respectively connected with the SW output end of the power supply chip U1 and the +5V power supply interface P1.

Pins

1 and 2 of a freewheeling diode D1 are respectively connected with an SW output end of a power chip U1 and a PGND ground end P2, a +5V power interface P1 is respectively connected with a microcontroller CPU, a CAN interface circuit 3 and an isolated RS232 interface circuit 2, a PGND ground end P2 is respectively connected with a ground end P2 of the microcontroller CPU, the CAN interface circuit 3 and a ground end P2 of the isolated RS232 interface circuit 2 and is grounded, a power input end filter capacitor C1 is an electrolytic capacitor, the capacitance value and the withstand voltage value of the power input end filter capacitor C2 are respectively 100 muF and 50V, a power output end filter capacitor C2 is an electrolytic capacitor, the capacitance value and the withstand voltage value of the power output end filter capacitor are respectively 47 muF and 16V, the model number of the freewheeling diode D1 is 1N5819, and the inductance value of the energy storage inductor L1 is 68.

The model of the chip of the microcontroller CPU is Infineon XC2234L, the microcontroller CPU is a chip with a CAN interface and an asynchronous serial interface, the CAN interface of the microcontroller CPU comprises a CAN-RX receiving end and a CAN-TX transmitting end, the CAN-RX receiving end and the CAN-TX transmitting end are respectively a P2.0 pin and a P2.1 pin of the microcontroller CPU, the asynchronous serial interface of the microcontroller CPU comprises a U0C1-TxD transmitting end and a U0C1-RxD receiving end, the U0C1-TxD transmitting end and the U0C1-RxD receiving end are respectively a P10.15 pin and a P10.14 pin of the microcontroller CPU, and a VCC signal end and a GND signal end of the microcontroller CPU are respectively connected with a +5V power interface P1 and a PGND P2 grounding end of the power supply circuit 1.

The circuit diagram of the CAN interface circuit 3 is shown in fig. 3, the CAN interface circuit 3 includes a CAN transceiver U2, a third filter capacitor C3, an impedance matching resistor R3, a CANH connection joint JP1, a CANL connection joint JP2, a chip model of a CAN bus driver U2 is TLE6250GV33, a TxD transmitting terminal and an RxD receiving terminal thereof are respectively connected with a CAN-TX transmitting terminal and a CAN-RX receiving terminal of a microcontroller CPU, the CAN-TX transmitting terminal and the CAN-RX receiving terminal are respectively connected with a CANH connection joint JP1 and a CANL connection joint JP2, a VCC signal terminal and a V33 signal terminal are connected with a +5V power interface P1 of a power supply circuit 1, a GND signal terminal and an INH signal terminal are connected with a PGND grounding terminal P2 of the power supply circuit 1, a pin # 1 and a pin # 2 of the impedance matching resistor R3 are respectively connected with a CANH signal terminal and a CANL signal terminal of a CAN transceiver U2 and a CANL signal terminal, a pin # 1 and a pin # 2 of a third filter capacitor C3 are respectively connected with a GND signal terminal and a GND signal terminal U2, the resistance of the impedance matching resistor R3 is 120 Ω, and the capacitance and withstand voltage of the third filter capacitor C3 are 0.1 μ F and 16V, respectively.

Fig. 4 shows a circuit diagram of the isolated RS232 interface circuit 2, where the isolated RS232 interface circuit 2 includes an isolated RS232 transceiver U3, a first decoupling capacitor C4, a second decoupling capacitor C6, a first filter capacitor C5, a second filter capacitor C9, a first charge pump capacitor C7, a second charge pump capacitor C8, an RS232 connection socket J2, and an isolated ground terminal P3, a chip model of the isolated RS232 transceiver U3 is ADM3251E, a VCC power supply terminal and a GND ground terminal of the isolated RS232 transceiver U3 are respectively connected to the +5V power supply interface P1 and the PGND ground terminal P2 of the power supply circuit 1, a VCC power supply terminal of the isolated RS232 transceiver U3 is a # pin 2 and a # pin 3 of the isolated RS232 transceiver U3, and a ground terminal of the isolated RS232 transceiver U3 is a # pin 4, a # pin 5, a # pin 6, a # pin 7, a # pin 10 and a # pin of the isolated RS232 transceiver U3. The ROUT receiver output signal terminal and the TIN transmitter input signal terminal of an isolated RS232 transceiver U3 are respectively connected with the U0C1-RxD receiving terminal and the U0C1-TxD transmitting terminal of a microcontroller CPU, the RIN receiver input signal terminal, the TOUT transmitter output signal terminal and the GNDISO isolated ground terminal of the isolated RS232 transceiver U3 are respectively connected with the 1# pin, the 2# pin and the 3# pin of an RS232 connecting socket J2, the 1# pin and the 2# pin of a first decoupling capacitor C4 are respectively connected with the VCC power terminal of an isolated RS232 transceiver U3 and the PGND ground terminal P2 of a power circuit 1, the 1# pin and the 2# pin of a second decoupling capacitor C6 are respectively connected with the VISO isolated power terminal and the isolated ground terminal P3 of an isolated RS232 transceiver U3, the 1# pin and the 2# pin of a first filter capacitor C5 are respectively connected with the VISO isolated power terminal and the VISO + V power terminal of the isolated RS232 transceiver U3, the pin # 1 and the pin # 2 of the second filter capacitor C9 are respectively connected with the V-power terminal of the isolated RS232 transceiver U3 and the isolated ground terminal P3, the pin # 1 and the pin # 2 of the first charge pump capacitor C7 are respectively connected with the C1+ signal terminal and the C1-signal terminal of the isolated RS232 transceiver U3, the pin # 1 and the pin # 2 of the second charge pump capacitor C8 are respectively connected with the C2+ signal terminal and the C2-signal terminal of the isolated RS232 transceiver U3, and the isolated ground terminal P3 is connected with the GNDISO isolated ground terminal of the isolated RS232 transceiver U3.

The working process of the utility model is as follows: (1) the power input plug J1 was connected to a commercially available +12V DC regulated power supply. (2) The Tx sending end, the Rx receiving end and the GND grounding end of an RS232 interface of an instrument are respectively connected with the RIN signal end, the TOUT signal end and the GNDISO isolation grounding end of an RS232 connecting socket J2. (3) The CANH connector JP1 and the CANL connector JP2 are connected to a CAN _ H signal line and a CAN _ L signal line of a CAN bus of an external industrial field network, respectively. (4) And the built-in outsourced communication software of the microcontroller CPU reads serial data of the RS232 connection socket J2 in real time and then sends the serial data to a CAN bus of an external industrial field network through a CANH connection joint JP1 and a CANL connection joint JP 2.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope of the present invention, and these modifications or replacements should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. The converter for converting the isolated RS232 data port into the CAN bus is characterized by comprising a power supply circuit (1), and a microcontroller CPU, a CAN interface circuit (3) and an isolated RS232 interface circuit (2) which are respectively connected with the power supply circuit (1), wherein the microcontroller CPU is correspondingly connected with the isolated RS232 interface circuit (2) and the CAN interface circuit (3) through an asynchronous serial interface and a CAN interface, an RS232 connection socket (J2) of the isolated RS232 interface circuit (2) is connected with the RS232 interface of an instrument, and a CANH connection joint (JP1) and a CANL connection joint (JP2) of the CAN interface circuit (3) are connected with the CAN bus of an external industrial field network.

2. The isolated RS232 data port to CAN bus converter according to claim 1, wherein the power circuit (1) comprises a power input socket (J1), a power chip (U1), a power input terminal filter capacitor (C1), a power output terminal filter capacitor (C2), a freewheeling diode (D1), an energy storage inductor (L1), +12V power interface (P0), +5V power interface (P1), and a PGND ground terminal (P2), wherein the IN power input terminal of the power chip (U1) is connected to the V + signal terminals of the +12V power interface (P0) and the power input socket (J1), the power ground terminal (GND) is connected to the PGND ground terminal (P2) and the V-signal terminal of the power input socket (J1), the SHDN off control terminal is connected to the PGND (P2), and the feedback terminal is connected to the +5V power interface (P1), the SW output end is connected with the +5V power interface (P1) through the energy storage inductor (L1), the power input end filter capacitor (C1) is connected in parallel with the output end of the power input socket (J1), the anode of the power supply output end filter capacitor (C2) is connected with the +5V power supply interface (P1), the cathode is connected with the PGND grounding end (P2), the anode of the freewheeling diode (D1) is connected with the PGND grounding end (P2), the cathode is connected between the SW output end of the power chip (U1) and the energy storage inductor (L1), the +5V power interface (P1) is respectively connected with the microcontroller CPU, the CAN interface circuit (3) and the isolated RS232 interface circuit (2), and the PGND grounding end (P2) is respectively connected with grounding ends of the microcontroller CPU, the CAN interface circuit (3) and the isolated RS232 interface circuit (2) and grounded.

3. An isolated RS232 data port to CAN bus converter according to claim 2 characterized in that the CAN interface circuit (3) comprises a CAN transceiver (U2), a third filter capacitor (C3), an impedance matching resistor (R3), a CANH connection (JP1) and a CANL connection (JP2), wherein the CAN transceiver (U2) communicates with the microcontroller CPU through the CAN interface of the microcontroller CPU and is connected with the CAN bus of the external industrial field network through the CANH connection (JP1) and the CANL connection (JP2), the VCC power supply terminal of the CAN transceiver (U2) is connected with the +5V power supply interface (P1), the GND terminal is connected with the PGND ground (P2), the impedance matching resistor (R3) is connected between the CANH connection (JP1) and the CANL connection (JP2), the third filter capacitor (C3) is connected between the VCC power supply terminal and GND ground terminal of the CAN transceiver (U2).

4. The isolated RS232 data port to CAN bus converter according to claim 2, wherein the isolated RS232 interface circuit (2) comprises an isolated RS232 transceiver (U3), a first decoupling capacitor (C4), a second decoupling capacitor (C6), a first filter capacitor (C5), a second filter capacitor (C9), a first charge pump capacitor (C7), a second charge pump capacitor (C8), an RS232 connection socket (J2), and an isolated ground terminal (P3), wherein the VCC power terminal and the GND terminal of the isolated RS232 transceiver (U3) are connected to the +5V power interface (P1) and the PGND ground terminal (P2), respectively, the ROUT receiver output signal terminal and the TIN transmitter input signal terminal of the isolated RS232 transceiver (U3) are connected to the asynchronous serial interface of the microcontroller CPU, and the RIN receiver input signal terminal of the isolated RS232 transceiver (U3) is connected to the asynchronous serial interface of the microcontroller CPU, The TOUT transmitter output signal terminal and GNDISO isolation ground terminal are connected with the RS232 connection socket (J2), the pin No. 1 and the pin No. 2 of the first decoupling capacitor (C4) are respectively connected with the VCC power terminal and the PGND ground terminal (P2) of the isolation RS232 transceiver (U3), the pin No. 1 and the pin No. 2 of the second decoupling capacitor (C6) are respectively connected with the VISO isolation power terminal and the isolation ground terminal (P3) of the isolation RS232 transceiver (U3), the first filter capacitor (C5) is connected between the VISO isolation power terminal and the V + power terminal of the isolation RS232 transceiver (U3), the second filter capacitor (C9) is connected between the V-power terminal and the isolation ground terminal (P3) of the isolation RS232 transceiver (U3), the first charge pump capacitor (C7) is connected between the C-signal terminal and the C-82 1 of the isolation RS232 transceiver (U8545), the second charge pump capacitor (C8) is connected between a C2+ signal terminal and a C2-signal terminal of the isolated RS232 transceiver (U3), and the isolated ground terminal (P3) is connected with a GNDISO isolated ground terminal of the isolated RS232 transceiver (U3).

5. The isolated RS232 data port to CAN bus converter as claimed in claim 2, wherein the power chip (U1) has a model number MIC4680-5.0BM and the freewheeling diode (D1) has a model number 1N 5819.

6. The isolated RS232 data port to CAN bus converter as claimed in claim 2, wherein the power input filter capacitor (C1) is an electrolytic capacitor with capacitance and voltage withstanding values of 100 μ F and 50V, respectively, the power output filter capacitor (C2) is an electrolytic capacitor with capacitance and voltage withstanding values of 47 μ F and 16V, respectively, and the inductance of the energy storage inductor (L1) is 68 μ H.

7. The isolated RS232 data port to CAN bus converter according to claim 3, wherein the CAN transceiver (U2) is TLE6250GV33, the impedance matching resistor (R3) has a resistance of 120 Ω, and the third filter capacitor (C3) has a capacitance and a withstand voltage of 0.1 μ F and 16V, respectively.

8. The converter of claim 4, wherein the isolated RS232 transceiver (U3) is of type ADM 3251E.

9. The isolated RS232 data port to CAN bus converter according to claim 4, wherein the capacitance and withstand voltage of the first decoupling capacitor (C4), the second decoupling capacitor (C6), the first filter capacitor (C5), the second filter capacitor (C9), the first charge pump capacitor (C7) and the second charge pump capacitor (C8) are 1 μ F and 25V respectively.

10. The isolated RS232 data port to CAN bus converter as claimed in claim 1, wherein the microcontroller CPU has a chip model number Infineon XC 2234L.