CN103336477A

CN103336477A - Analog output module based on CAN bus

Info

Publication number: CN103336477A
Application number: CN2013102953074A
Authority: CN
Inventors: 陈丽娟; 朱三超; 张发光; 王琨; 张国萍
Original assignee: Guizhou University
Current assignee: Guizhou University
Priority date: 2013-07-15
Filing date: 2013-07-15
Publication date: 2013-10-02

Abstract

The invention discloses an analog output module based on a CAN (Controller Area Network) bus, which comprises a CAN bus communication interface part, a peripheral circuit part and an I/O (Input/Output) interface part. According to the analog output design based on the CAN bus, a data processing and output module with a CAN bus communication interface is designed based on a CAN bus 2.0B protocol, a hardware design of an intelligent node takes a control processor as a core, a CAN bus controller and a CAN bus transceiver are combined, and the control processor is externally connected with a watchdog module to prevent a program from running and flying, so that a purpose of improving the instantaneity and the reliability of analog remote control is achieved. The analog output module is simple in structure, low in cost and good in using effect.

Description

Analog output module based on the CAN bus

Technical field

The present invention relates to areas of information technology, particularly a kind of analog output module based on the CAN bus.

Background technology

The CAN bus is one of most widely used fieldbus in the world, has the operation of many main websites and disperses the universal serial bus of arbitration and the characteristics of broadcast communication.On the CAN bus arbitrary node can be at any time on one's own initiative on the network other node send information and be regardless of primary and secondary, therefore can between each node, realize free communication.The CAN bus has the traffic rate height, realizes and a kind of fieldbus that has formed international standard of many characteristics such as cost performance height easily, be applied to various fields at present, has the powerful market competitiveness.In the process of current industry spot control, usually need measure physical quantities, perhaps control physical quantity, in such industry spot, analog quantity has obtained using widely.Analog quantity can reflect the change procedure of physical quantity accurately, as control temperature, flow, speed etc.Industry Control of today is generally all being selected Long-distance Control, and people have seldom arrived on-the-spot inspection, so bus is arisen at the historic moment now.

Summary of the invention

Technical matters to be solved by this invention is: a kind of analog output module based on the CAN bus is provided, and it improves real-time and the fiduciary level of analog quantity Long-distance Control, to overcome the deficiencies in the prior art.

The analog output module that is achieved in that based on the CAN bus of the present invention, comprise CAN bus communication interface section, peripheral circuit part and I/O interface section, CAN bus communication interface section is by CAN bus controller (1), photoelectric isolation module II(6) and CAN bus transceiver (8) form, CAN bus controller (1) is by photoelectric isolation module II(6) be connected with CAN bus transceiver (8); The peripheral circuit part is made up of control processor (2), watchdog chip (5) and power module (10); The I/O interface section is by DA chip (4) and photoelectric isolation module I(3) form DA chip (4) and photoelectric isolation module I(3) be connected; Control processor (2) connects respectively at CAN bus controller (1), watchdog chip (5) and DA chip (4); Power module (10) respectively with CAN bus controller (1), control processor (2), DA chip (4) and CAN bus transceiver (8) is connected, and pass through d-c transformer (11) respectively with photoelectric isolation module I(3) and photoelectric isolation module II(6) be connected.

It is SJA1000 that the CAN controller is selected model for use, CAN bus transceiver model is 82C250, all select isolation optocoupler 6N137 for use with photoelectric isolation module II, their common CAN bus communication interface sections of forming, be responsible for the both-way communication between this node and the bus, photoelectric isolation module II can strengthen the antijamming capability of CAN bus node.

The control processor can be selected the 89C51 single-chip microcomputer for use, the control of responsible node and computing.

Watchdog chip is selected X25045 for use, prevents program fleet.

The DA chip is selected DAC0832 for use, and photoelectric isolation module I selects for use and isolates optocoupler 6N137.DA chip and photoelectric isolation module I form the I/O interface section jointly, and it carries out aanalogvoltage output control according to the instruction of control processor to on-the-spot device, and this part is converted into analog quantity by the DA chip with digital quantity and outwards exports.

Owing to adopted technique scheme, compared with prior art, the present invention is based on the analog quantity output design of CAN bus, on the basis of CAN bus 2.0B agreement, designed the data that have CAN bus communication interface and handled and output module; The hardware design of intelligent node is core with the control processor, in conjunction with CAN bus controller and CAN bus transceiver, and controlling external watchdog module on the processor, prevent program fleet, to realize improving the real-time of analog quantity Long-distance Control and the purpose of fiduciary level.The present invention is simple in structure, and is with low cost, and result of use is good.

Description of drawings

Accompanying drawing 1 is structural representation of the present invention;

Accompanying drawing 2 is CAN bus controller of the present invention and the connecting circuit figure that controls processor;

Accompanying drawing 3 is the connecting circuit figure of CAN bus controller of the present invention and CAN bus transceiver;

Accompanying drawing 4 is the circuit diagram of power module of the present invention;

Accompanying drawing 5 is the circuit diagram of photoelectric isolation module of the present invention;

Accompanying drawing 6 is the circuit diagram of crystal oscillating circuit of the present invention;

Accompanying drawing 7 is aanalogvoltage output interface circuit figure of the present invention;

Accompanying drawing 8 is the process flow diagram of the course of work of the present invention.

Embodiment

Embodiments of the invention: based on the structure of the analog output module of CAN bus as shown in Figure 1, comprise CAN bus communication interface section, peripheral circuit part and I/O interface section, CAN bus communication interface section is by CAN bus controller 1, photoelectric isolation module II6 and CAN bus transceiver 8 are formed, and CAN bus controller 1 is connected with CAN bus transceiver 8 by photoelectric isolation module II6; The peripheral circuit part is made up of control processor 2, watchdog chip 5 and power module 10; The I/O interface section is made up of DA chip 4 and photoelectric isolation module I3, and DA chip 4 is connected with photoelectric isolation module I3; Control processor 2 connects respectively at CAN bus controller 1, watchdog chip 5 and DA chip 4; Power module 10 is respectively with CAN bus controller 1, control processor 2, DA chip 4 and CAN bus transceiver 8 is connected, and pass through d-c transformer 11 and be connected with photoelectric isolation module I3 and photoelectric isolation module II6 respectively.

In use, connect output port 7 in the I/O interface section, connect Controller Area Network BUS 12 at CAN bus transceiver 8.

CAN bus controller 1 is connected as shown in Figure 2 with the circuit of control processor 2, and the ADO～AD7 of CAN bus controller 1 is connected to the PO mouth of control processor 2;

Figure 2013102953074100002DEST_PATH_IMAGE001

Be connected to the P2.0 of control processor 2, P2.0 is that 0 CPU chip external memory address can be chosen 1, two ALE of CAN bus controller to link to each other to realize latching of address, thereby data and address are separately; Both ,

Figure 2013102953074100002DEST_PATH_IMAGE003

End links to each other respectively, and CPU can carry out corresponding read/write operation to the register of CAN bus controller 1 by these addresses.Have again, CAN bus controller 1

End and control processor 2 Link to each other, control processor 2 also can be visited CAN bus controller 1 by interrupt mode.

CAN bus controller 1 is connected as shown in Figure 3 with the circuit of CAN bus transceiver 8, and VDD and VSS connect high voltage and ground respectively; MODE connects high level, the TXO of CAN bus controller 1 and RXO link to each other with CAN bus transceiver 8 after by high speed photo coupling 6N137, two power supply VCC and VDD that the optocoupler partial circuit adopts must isolate fully, the isolation fully of power supply adopts the small-power power isolation module to realize that the CANH of CAN bus transceiver 8 links to each other with the CAN bus by the resistance of 15 Ω separately with the CAHL pin; The little electric capacity of 2 30pF in parallel between CANH and CANL and the ground, in addition, between two CAN bus incoming ends and ground, connect 1 anti-lightning strike pipe respectively, when occurring the transition interference between two input ends and the ground, can play the certain protection effect by putting a little of anti-lightning strike pipe; Connect a slope resistance on the Rs pin of CAN bus transceiver 8, be used for control and rise and descending slope, reducing the Radio frequency interference (RFI) resistance sizes can be according to suitable high adjustment of bus communication speed, generally between 16～140k Ω.

The connecting circuit annexation of power module 10 as shown in Figure 4, at first by transformer the 220V alternating current is converted into the alternating current of 9V, by the bridge type rectifier AC rectification is being become direct current, C11 and C12 are respectively input end and output terminal filter capacitor, integrated regulator 7805 again the direct current of 9V is converted into need+the 5V direct current.

Crystal oscillating circuit such as Fig. 6 do not have the onboard clock circuit in CAN bus controller 1 and the CAN bus transceiver 8, need an external crystal oscillator to produce clock frequency, and clock signal is provided.

The aanalogvoltage output interface circuit as shown in Figure 7,

, With

Directly ground connection allows chip operation at direct-passing mode;

Ground connection makes chip maintenance work, and ILE connects high level and allows the signal input, and Data In-Line connects the P1 mouth of control processor 2; Digitally separately be connected IOUT2 ground connection with simulation; The D/A transformation result adopts current forms output, and the linear operational amplifier of a high input impedance connects IOUT1 and the IOUT2 port of chip and realizes; In order to prevent disturbing, between the output port of operational amplifier and port, connect a 6N137 opto-coupler chip.

Main program flow chart after system powers on, is done the initialization of system as shown in Figure 8, and message to be received whether in the check CAN bus controller 1 if any receiving message, outwards sends the form of data with aanalogvoltage.

Claims

1. analog output module based on the CAN bus, comprise CAN bus communication interface section, peripheral circuit part and I/O interface section, it is characterized in that: CAN bus communication interface section is by CAN bus controller (1), photoelectric isolation module II(6) and CAN bus transceiver (8) form, CAN bus controller (1) is by photoelectric isolation module II(6) be connected with CAN bus transceiver (8); The peripheral circuit part is made up of control processor (2), watchdog chip (5) and power module (10); The I/O interface section is by DA chip (4) and photoelectric isolation module I(3) form DA chip (4) and photoelectric isolation module I(3) be connected; Control processor (2) connects respectively at CAN bus controller (1), watchdog chip (5) and DA chip (4); Power module (10) respectively with CAN bus controller (1), control processor (2), DA chip (4) and CAN bus transceiver (8) is connected, and pass through d-c transformer (11) respectively with photoelectric isolation module I(3) and photoelectric isolation module II(6) be connected.