CN221240359U

CN221240359U - CAN to optical fiber circuit for single machine communication in railway auxiliary power supply box

Info

Publication number: CN221240359U
Application number: CN202322827042.XU
Authority: CN
Inventors: 李凡; 高明久
Original assignee: Nanjing Zhizhuo Electronic Technology Co ltd
Current assignee: Nanjing Zhizhuo Electronic Technology Co ltd
Priority date: 2023-10-21
Filing date: 2023-10-21
Publication date: 2024-06-28
Anticipated expiration: 2033-10-21

Abstract

The utility model belongs to the technical field of railway auxiliary power boxes, in particular to a CAN-to-optical fiber circuit for single-machine communication in a railway auxiliary power box, which aims at the problems that the power devices in the existing railway CAN-to-optical fiber circuit are increased, the electromagnetic environment is bad, a twisted pair is not suitable for high-speed and large-data-volume transmission, the situation of losing data frames and the like CAN occur, a CAN isolation transceiver and other devices are required to be added, the use cost is increased, the CAN transceiver is extremely easy to damage, and the use and maintenance are difficult, and the scheme is provided. The utility model has simple circuit structure, fewer practical devices and no need of isolation, and each CPU control board can complete TTL level receiving and transmitting only by 12 devices, and is a device with lower cost. The use cost is reduced, the reliability is high, and the device is not easy to damage.

Description

CAN to optical fiber circuit for single machine communication in railway auxiliary power supply box

Technical Field

The utility model relates to the technical field of railway power supply boxes, in particular to a CAN fiber conversion circuit for single machine communication in a railway auxiliary power supply box.

Background

Before the utility model, most CAN circuits are communicated by adopting twisted pair and are isolated by using a TTL-to-CAN isolation module, although the cost of using the twisted pair is low, the use is convenient, as the communication distance is increased, the power devices in a power supply box are increased, the electromagnetic environment is bad, the twisted pair is not suitable for high-speed and large-data-volume transmission, the situations of losing data frames and the like CAN be caused, and devices such as a CAN isolation transceiver and the like are required to be added, the use cost is increased, and the CAN transceiver is extremely easy to damage and difficult to use and maintain.

In order to improve the anti-interference degree, improve the communication stability between single machines and reduce the device cost, a method for replacing twisted pair wires by using optical fibers is provided, optimization is performed on the basis of other CAN-to-optical fiber circuits, the communication circuit is simplified, the use cost is reduced, and the transmission stability is improved, so that the problem of communication blockage caused by complex electromagnetic environment in an auxiliary power supply box is solved.

Disclosure of utility model

The utility model aims to solve the defects that the power devices in the CAN-to-optical fiber circuit in the existing railway are increased, the electromagnetic environment is bad, twisted pair wires are not suitable for high-speed and large-data-volume transmission, the situation of losing data frames and the like CAN be caused, devices such as a CAN isolation transceiver and the like are needed to be added, the use cost is increased, the CAN transceiver is extremely easy to damage, and the use and the maintenance are difficult, and the CAN-to-optical fiber circuit for single-machine communication in the railway auxiliary power supply box is provided.

In order to achieve the above purpose, the present utility model adopts the following technical scheme:

The CAN fiber conversion circuit comprises a bus side circuit, a TX1 device, a peripheral circuit, an RX1 device and a peripheral circuit, wherein the TX1 device is connected with a current-limiting diode R2 and an upper resistor R1, the current-limiting diode R2 is connected with a decoupling capacitor C3, the current-limiting diode R2 is connected with a filter capacitor C1, the RX1 device is connected with a receiver power decoupling filter C4, the RX1 device is connected with divider resistors R3 and R4, and the bus side circuit comprises an optical fiber transmitter, an optical fiber receiver, a TTL fiber-to-CAN chip and a logic level conversion circuit.

Preferably, the TX1 device is a HFBR1522 of model An Huagao.

Preferably, the RX1 device is a An Huagao HFBR2522.

The utility model has simple circuit structure, fewer practical devices and no need of isolation, and each CPU control board can finish TTL level receiving and transmitting only by 12 devices, and is a device with lower cost. The use cost is reduced, the reliability is high, and the device is not easy to damage.

Drawings

FIG. 1 is a schematic diagram of MCU side circuit of CAN-to-fiber circuit for single machine communication in railway auxiliary power box;

FIG. 2 is a schematic diagram of a bus-side circuit of a CAN-to-fiber circuit for single-machine communication in a railway auxiliary power box according to the present utility model;

fig. 3 is a block diagram of an optical fiber-to-CAN circuit system of a CAN-to-optical fiber circuit for single machine communication in a railway auxiliary power box.

Detailed Description

The technical solutions of the present embodiment will be clearly and completely described below with reference to the drawings in the present embodiment, and it is apparent that the described embodiments are only some embodiments of the present embodiment, not all embodiments.

Examples

Referring to fig. 1-3, a CAN fiber conversion circuit for single machine communication in a railway auxiliary power box comprises a bus side circuit, a TX1 device, a peripheral circuit, an RX1 device and a peripheral circuit, wherein the TX1 device is connected with a current-limiting diode R2 and an upper resistor R1, the current-limiting diode R2 is connected with a decoupling capacitor C3, the current-limiting diode R2 is connected with a filter capacitor C1, the RX1 device is connected with a receiver power decoupling filter C4, the RX1 device is connected with voltage dividing resistors R3 and R4, and the bus side circuit comprises an optical fiber transmitter, an optical fiber receiver, a TTL-to-CAN chip and a logic level conversion circuit.

In this embodiment, first, the TX transmitting pin of the MCU sends a level, and enters a logic level conversion circuit, the chip signal is SN75452B of TI, the chip has three points, 1, level conversion, the TTL signal level sent by the MCU is 3.3V, and is converted into a TTL level of 5V through logic conversion, so that the optical fiber emits light, 2, logic conversion function, and control of the chip model or connection mode can realize whether the TTL level corresponds to optical fiber transmission, where the mode is a nand gate+triode chip, when the TX of the TTL sends a high level, i.e. the 7 pin of U1 receives a high level, the 6 pin maintains a state of a pull-up high level at all times, i.e. the 5 pin outputs a high level, and the TTL level is supplied to the optical fiber transmitting circuit. 3, can realize the larger drive current to supply the optical fiber send diode, when the peripheral circuit of the optical fiber is modified, this chip can offer higher push current and irrigate the electric current ability. The main function of C2 is to cling to the power supply pin of the logic chip to realize decoupling filtering function.

In this embodiment, the optical fiber transmission circuit, in fig. 1: namely a TX1 device and a peripheral circuit, R2 is a current-limiting diode of the optical fiber transmitter, the light-emitting brightness can be modified by modifying the resistance value, C3 is used as a power supply filtering decoupling capacitor, R1 is a pull-up resistor of the optical fiber transmitter, the resistor is used for keeping the cathode of the light-emitting diode in a high-level state when the TX of the MCU and the 5 pins of U1 output low level, the light-emitting diode is prevented from being turned on by mistake, C1 is a filter capacitor of pull-up voltage, and the light-emitting diode is prevented from being turned on by mistake due to high-frequency interference. TX1 acts as a fiber optic transmitter with an integrated light emitting diode, HFBR1522, model An Huagao.

In this embodiment, the optical fiber receiving circuit, in fig. 1: namely an RX1 device and a peripheral circuit, C4 is used for decoupling and filtering a receiver power supply, R3 and R4 form a voltage dividing circuit, if the receiver receives an optical signal sent by a transmitter, a photodiode is turned on, a post-stage triode is driven by an operational amplifier to enable a pin 1 of the receiver to output 5V high level, but an RX pin of an MCU generally receives 3.3V voltage, so the voltage dividing circuit is used for dividing 5V to about 3.3V and supplying the voltage to the MCU. RX1 is HFBR2522 having a size An Huagao. The 2.5.8 pin of RX1 is pulled to GND, the 3 pin VCC pin is connected with 5V, and the 4 pin is suspended.

Bus side principle, as shown in fig. 2: the optical fiber transmitter, the optical fiber receiver, the TTL-CAN chip and the logic level conversion circuit. The working principle is as follows: when the receiver RX receives the optical signal, converts the optical signal into a level and outputs the level signal to the U2 chip, converts the level signal into a CAN signal, uses a plurality of bus devices to record the conversion circuit, combines all CAN signals together according to CANH and CANL to form a CAN bus, and adds a 120R termination resistor. When one device sends out a signal, the signal is converted to a bus, and then each sending circuit CAN send out the same signal to other devices through the sending circuit, so that CAN-to-optical fiber circuit communication is completed.

The optical fiber-to-CAN circuit system diagram is shown in FIG. 3: the MCU side circuit and the bus side circuit are connected through optical fibers to form a system communication circuit. The communication circuit of the system has the advantages of low cost, strong anti-interference performance, simple structure, convenient maintenance and the like.

The foregoing is only a preferred embodiment of the present utility model, but the scope of the present utility model is not limited thereto, and any person skilled in the art will be able to apply equally to the technical solution of the present utility model and the inventive concept thereof, within the scope of the present utility model.

Claims

1. The CAN fiber converting circuit comprises a bus side circuit, a TX1 device, a peripheral circuit, an RX1 device and a peripheral circuit, and is characterized in that a current limiting diode R2 and an upper resistor R1 are connected to the TX1 device, a decoupling capacitor C3 is connected to the current limiting diode R2, a filter capacitor C1 is connected to the current limiting diode R2, a receiver power decoupling filter C4 is connected to the RX1 device, and voltage dividing resistors R3 and R4 are connected to the RX1 device.

2. The CAN-to-fiber circuit for single machine communication in a railway auxiliary power box of claim 1, wherein the TX1 device is of the HFBR1522 type.

3. The CAN fiber optic circuit for stand-alone communications in a railway auxiliary power box of claim 1, wherein said RX1 device is of the type HFBR2522.

4. The CAN-to-fiber circuit for single machine communication in a railway auxiliary power box of claim 1, wherein the bus side circuit comprises a fiber optic transmitter, a fiber optic receiver, a TTL-to-CAN chip and a logic level conversion circuit.