CN202500555U - Data transmission system in petroleum logger - Google Patents

Abstract

The utility model discloses a data transmission system in a petroleum logger. Downhole collecting plates are connected with a downhole telemetering plate through a CAN (controller area network) bus, and the downhole telemetering plate is connected with a ground communication plate in a transformer-coupling transmission mode. According to the design of the data transmission system, a field CAN bus communication protocol meeting international standards is applied to data communication among the downhole collecting plates, so that the communication is ensured to have an extremely good error detection effect and an extremely low error rate. By virtue of a multi-master operating mode, various communication modes such as broadcasting and distributing are realized, and therefore the communication speed is high.

Description

Data transmission system in a kind of oil logging tool

Technical field

The utility model relates to oil logging tool, relates in particular to the data transmission system in a kind of oil logging tool.

Background technology

In oil well logging instrument, the data interaction between electric circuit in well adopts RS232, RS485, SPI communication modes to realize more.Lack perfect communication correction mechanism in the above-mentioned communication modes transfer of data, the accuracy of transmission is not high, and communication speed generally reduces.

In the transmission of oil reservoir logging cable data, a variety of instruments all adopt Manchester code to send the bulk information of being gathered to ground logging system.Manchester's code is a kind of important coded system of serial data transmission, has good interference free performance, generally realizes through HD15530 Manchester code coder.Because the limited production of external HD15530 manufacturer, domestic this chip price is expensive, causes present logger manufacturing and maintenance cost to increase; In addition, adopt the system of special-purpose graceful sign indicating number decoding chip, have that systemic-function is single, integrated level is not high; Shortcomings such as power consumption is bigger, and is compatible relatively poor.

The utility model content

To the problems referred to above that exist in the prior art, the utility model provides the data transmission system in a kind of oil logging tool.

The utility model provides the data transmission system in a kind of oil logging tool, and the down-hole collection plate is connected with the downhole telemetry plate through the CAN bus, and the downhole telemetry plate is connected through transformer coupled transmission means with the ground communications plate.

In one example, down-hole collection plate and downhole telemetry plate are provided with CAN isolation and driver module.

In one example, CAN isolates and comprises TMS320F2812 chip, ADuM1201 chip and the PCA82C250 chip that is connected in order with driver module, and the PCA82C250 chip inserts the CAN bus.

In one example; The downhole telemetry plate comprises data processing module, encoding process module, decoding process module; Modulation-demodulation circuit module and communication bus transformer; Data processing module, encoding process module and decoding process module are realized that by dsp chip the modulation-demodulation circuit module is connected with the communication bus transformer with dsp chip respectively, and the communication bus transformer inserts the MIL-STD-1553B data/address bus.

In one example, the ground communications plate also is connected with PC through USB interface.

In one example, the ground communications plate comprises the EZ-USBFX2 chip, and the EZ-USBFX2 chip is connected with the Acex1K30 chip.

In the utility model design, will have the Field Bus CAN communications protocol of international standard, be applied to the data communication between the collection plate of down-hole, guarantee that communication has fabulous error detection effect and extremely low error rate.Adopt many main working methods, realized the broadcasting and the multiple communication modes that distributes, communication speed is high.

The utility model is introduced a kind of based on the TMS320F2812DSP chip, realizes the method to the Manchester coded format Code And Decode of MIL-STD-1553B data bus protocol through software programming.Can replace special-purpose Manchester code codec chip HD15530, reduce instrument manufacturing and maintenance cost, improve system reliability.Under the constant condition of hardware, through the software setting, can realize communication interfaces with various graceful sign indicating number remote measurement pipe nipples, have compatible preferably.Ground telemetering and intercomputer are realized with USB interface, are convenient to the interface of equipment and computer, improve data transmission bauds.It is actual that design scheme satisfies the oil field downhole data communication.

Description of drawings

Come the utility model is done further explain below in conjunction with accompanying drawing, wherein:

Fig. 1 is the data transmission system structural representation in the oil logging tool;

Fig. 2 is the isolation sketch map in the underground communica tion;

Fig. 3 is a downhole telemetry plated construction sketch map;

Fig. 4 a and Fig. 4 b are the Manchester's code oscillograms;

Fig. 5 a-Fig. 5 f is a graceful Chester coded message frame synchronization oscillogram;

Fig. 6 is an information frame synchronous head exploded view;

Fig. 7 a-Fig. 7 d is a bus data decoding oscillogram;

Fig. 8 is that FX2 is connected sketch map with the hardware of FPGA.

The specific embodiment

The oil logging tool circuit structure is divided into aboveground and the down-hole two large divisions; Aboveground part mainly comprises the ground communications system; Electric power system and host computer function software, the down-hole part mainly comprises data acquisition module, downhole telemetry communication module and power transfer module.

The transfer of data of logging instrument comprises communication and ground system and PC communication three parts composition between data communication, downhole communication module and the surface telemetry system between the downhole data acquisition module.The scheme in communication that the utility model proposes is: through the CAN bus structures, adopt master-salve distributed TT&C system between downhole telemetry plate and the data acquisition board.Downhole telemetry plate and ground communications partly adopt transformer coupled transmission means, and downhole data transmission is arrived ground receiving system.Select the USB interface communication to realize between ground system and PC.As shown in Figure 1.

The CAN bus is up to the present unique fieldbus that international standard is arranged, and has outstanding flexibility, reliability and real-time.Its characteristics: directly transmission range can reach 10km farthest; The communication flank speed can reach 1Mbps; Adopt many main working methods, through the identifier filtering to message can realize point-to-point, a bit to several data communication modes such as multiple spot and overall situation broadcasting; Adopt nondestructive bus arbitration technology; Message adopts short frame structure, receives jamming rate extremely low; Every frame information all has CRC check, has fabulous error detection effect and extremely low error rate.

The general RS485 of selection of data acquisition and communication, RS232 agreement realize under the conventional well, in the utility model, are reliable transmission and the efficiency of transmission at a high speed that guarantees data, select local communication bus CAN protocol mode to accomplish the data communication between the collection plate of down-hole.Wherein, the downhole communication plate is a CAN network main control device, and each collection point adopts broadcast type to pass the host computer order down as the CAN node, and each node can be selected identical ID number, receives the order that is passed down by ground system synchronously.Adopt distributed reception to gather the receiver image data,, can realize the transfer of data between different CAN nodes of timesharing and main frame through disposing different ID number.The principal and subordinate distributes and makes up the network topology structure of TT&C system.Each website adopts wired connection, balance transmission mode.

In the design of CAN bus intelligent node circuit, adopt TMS320F2812 as microprocessor, this chip is 32 fixed point type dsp chips, integrated ECAN decoding circuit module on the sheet.The ECAN module is an enhancement mode CAN controller, is 32 senior CAN controllers of a new generation of TI company, and performance is equivalent to the high-end CAN controller (HECC, High-end CANController) that TI company's T MS470 Series of MCU is used.Its complete compatible CAN2.0B agreement can be used above-mentioned agreement and other controller serial communications in noisy environment.Adopt integrated CAN bus control unit TMS470 among the TMS320F2812.

PCA82C250 in the circuit design is the physical interface between CAN controller and the bus, and it can provide to the differential transmitting capacity of bus with to the differential receiving ability of CAN controller, and antijamming capability is strong.In limit current circuit can prevent to send output stage to power supply, or the short circuit of load.In addition, use PCA82C250 can increase communication distance, improve the moment antijamming capability of system, as shown in Figure 2.

Use ADuM1201 and realized the electrical isolation between CAN bus node and the controller DSP.ADuM1201 is the new product that ADI company releases, and it attendes institute's employing technology in electrical isolation is transformer isolation, directly on chip, makes the iCouple transformer through using the wafer scale manufacturing process, replaces conventional photoelectrical coupler.Adopt two passages that transform, the special construction that two channel direction are opposite is very suitable for the transmission of CAN bus signals, has simplified the hardware configuration of system greatly; Simultaneously, replace in the past 2, increased interchannel matching degree greatly, make system obtain better isolation performance by 1 isolating chip.

Should be noted that in the circuit design: the left side power port VDD1 of ADuM1201, GND1 and the DSP_3.3V of dsp chip link to each other with VSS (DSP_GND) digitally; Another group power end VDD2, GND2 link to each other with CAN_GND with the CAN_VCC of CAN bus power source; Two groups of power supplys are isolated through DC-DC, thereby make isolation fully between CAN bus control unit and the CAN bus.The receiving terminal CANRXA of TMS320F2812 is connected with the VOA of ADuM1201 end; The transmitting terminal CANTXA of TMS320F2812 is connected with the VIB of ADuM1201 end; The VIA end of ADuM1201 is connected with PCA82C250 receiving terminal RXD; The VOB end of ADuM1201 is connected with PCA82C250 transmitting terminal TXD, and CAN_H end and the CAN_L termination of ADuM1201 are gone into the CAN bus.

Manchester (Manchester) sign indicating number is claimed digital diphase code again; Because there is very strong timing component in it; There is not DC component; Have self-synchronization and good interference free performance, be widely used in the oil well logging instrument, realize the data communication between down-hole acquisition system and the ground receiving system.This paper introduces a kind of based on the TMS320F2812DSP chip, realizes the method to the Manchester coded format Code And Decode of MIL-STD-1553B data bus protocol, has solved the reliability of logging instrument high speed data transmission system well.

As shown in the figure, communication system is selected the TMS320F2812 chip for use, it the time TI company up-to-date release dsp chip, be 32 most advanced on the present international market, that function is the most powerful fixed-point DSP chip, clock frequency can reach 150MHz.It had both had digital signal processing capability, had powerful incident management ability and embedded Control function again.

In system; DSP is used to carry out communications protocol; Receive the data of the Manchester's code on the bus; Form according to the rules sends Manchester II type coded data, state or command word, realizes the interface function of the interface channel at bus and terminal, and the above ground portion of control logger communication system.Wherein, The Manchester code codec adopts on the DSP sheet time block to realize, is used to accomplish the string and and and the generation and the functions such as detection, Address Recognition and wrong detection of string conversion, synchronous head of modulation and demodulation, the data of transmission and reception, the Manchester code of data.

Based on its information frame form of Manchester sign indicating number of MIL-STD-1553B coded format, every bit stealing time 1us forms by 20.Its 1～3 is synchronous prefix, is used to represent frame type, the beginning of identification frames.If preceding 1.5 is high level, represent that this frame is order/status word during for low level for back 1.5, preceding 1.5 is low level, back 1.5 are expressed as data word, decoder synchronous prefix extraction bit synchronization information also capable of using during for high level.Wherein 4～19 is data to be encoded, and the 20th is check bit, carries out even-odd check to 4～19.

In the process of whole Manchester's code and decoding, designed following module: clock module Clk, data shift register Data, bit-count register Count, frequency counter Feq, parity bit P according to bus protocol.Because local system clock Clk is 150 times of data transmission rate, so the accurate clock that timer realizes that encoding and decoding are required is set in DSP, its clock cycle is 1/20 of the data bit encoding and decoding cycle.Use frequency counter Feq the clock cycle is carried out frequency division, count down to 20 zero clearings and restart counting.Preceding 10 count tables show the preceding 0.5bit of data bit, and back 10 count tables show the back 0.5bit of data bit.

The process of Manchester code coding is meant that the dsp code module receives 16 data, instruction and status word from the DSP program module, and sends to bus with 1Mb Manchester II type encoded serial data.Coding module is accomplished and is comprised functions such as sending control, synchrodata coding, odd even generation, through being sent to the communication transformer module after the 74ALVC164245 completion level translation.

According to bus protocol, the width of sync bit should be three data bit, if information frame is a command word; Then the waveform of previous subluxation is for just; The half-wave shape in back is for negative, and is if information frame is a data word, then opposite with the command word waveform; So the synchronous head of frame takies three bit data positions, totally 60 clock cycle.Preceding 15 clock cycle are 1 (or 0), and back 15 clock cycle are 0 (or 1).1～3 expression sync bit of digit counter.

Be exactly the coding of data word after the synchronous head then, each data symbols (bit) mid point at interval is with trailing edge representative data " 1 ", rising edge representative data " 0 ".The lowest order of shift register is represented current data to be encoded position, can only be shifted once per 20 clock cycle.The position count value be 4～19 and frequency counter Feq value read in the lowest order of shift register when being zero, export corresponding waveform, when frequency counter Feq value is 10 output waveform is carried out saltus step, to produce corresponding hopping edge., bit counter value shows ten eight bit data completion coding when being added to 19.

Parity check bit is positioned at the 20th of information frame.After ten eight bit data end-of-encodes, parity check bit calculates check results according to 18 shifted data of shift register, exports corresponding saltus step waveform according to check results.

Fig. 4 a and Fig. 4 b have shown the Manchester code waveform.

When the process of Manchester code decoding is DSP decoder module reception data, receive the serial data of Manchester's code, realize that synchronous head detects, data detect, odd even detects, the data after handling are sent into the DSP program module analyze.Receiving data is that the method that adopts sampling to judge realizes.Promptly count, under the situation of same polarity, confirm the polarity of subluxation Manchester code when counting down to the value of a setting with counter.The Manchester code of opposed polarity is combined to form complete information frame.

Synchronous head comprises three bit data positions, preceding 1.5 opposite with back 1.5 polarity.In the waveform monitoring of reality, obtain the synchronous head of following six kinds of information frames, shown in Fig. 5 a-Fig. 5 f.

Fig. 5 a-Fig. 5 c representes three kinds of synchronous heads of command frame, and Fig. 5 d-Fig. 5 f representes three kinds of synchronous heads of Frame.In waveform monitoring, if only judge that Fig. 5 c and Fig. 5 f waveform are not the synchronous heads of frame, that will drop-out, also might cause information frame type error in judgement.

Sign indicating number type characteristic according to Manchester code can know the key of detecting synchronous head is how to discern preceding 1.5 and the 1.5 reversed polarity positions, back of Manchester code.Above Fig. 5 c is an example, introduces way to solve the problem.

In Fig. 6, Clk representes that counter overflows the encoded clock that is produced, and the clock cycle is its ten times, and Manchester code comprises three 1.5 adjacent opposite polarity synchronous code at least.On encoded clock, the every subluxation of Manchester code is indicated.

The first step; When the Manchester code and 4,5 of 1,2,3 subluxation identical polars in monitoring figure, 6 subluxation reversed polarity Ma Shi; They are preceding 1.5 and back 1.5 of the frame synchronization head for preliminary judgement, if two subluxation Manchester code polarity differences closelying follow are then explained the time numeric data code that it follows closely at the back; Meet the Manchester code coding protocol, can carry out the reception of numeric data code.If but two subluxation Manchester code polarity closelying follow are identical, so just do not met the rule of Manchester code coding, like 7,8 subluxations among the figure, some coding chips detect it and produce mistake, cause loss of data or data entanglement.In the design, when running into the identical situation of 7,8 subluxations, abandon preceding 1.5 of initial decision, reset preceding 1.5 of position to 4,5,6 subluxations

In second step, continue the 9th subluxation is detected.If 9 and 7,8 polarity are different, then withdraw from the hypothesis of this synchronous head, restart preceding 1.5 detection of frame synchronization head.If 7,8,9 subluxation polarity are identical, then 4,5,6,7,8,9 have formed a frame synchronization head again, have got back to the situation that the first step runs into.Detect the polarity of 10,11 two subluxations once more, receive if get into numeric data code on the contrary, identical words restarted for second step.

In the 3rd step, more than having moved, after two steps, obtained a synchronous head of information frame, the numeric data code of closelying follow thereafter.According in the synchronous head preceding 1.5 with back 1.5 polarity, can confirm the type of information frame.

After synchronous head detected, what be right after afterwards was exactly numeric data code, and the combined result of any two bits has only four kinds: 00,01,10,11; See that from waveform it can go out four kinds of situation, shown in Fig. 7 a-Fig. 7 d.

Can find out only have position of waveform width and half bit width of two kinds this moment by Fig. 7 a-Fig. 7 d, so because the clock of counting is 20 times of data-bit encoding, so the scope of the count value of corresponding counts device is between 8～12 and 18～22.So, as long as the data bit count value that obtains satisfies above two width ranges, think that then data format is correct, the data of reception are effective, accomplished the data sync reception.

To each frame data, after receiving the sixteen bit data, last position is a parity values, if DRP data reception process does not go wrong, then the parity values of data is corresponding with the value that receives.

In the process of batch data transmission, in order to ensure reliability of data transmission, add the CRC algorithm, serial data is carried out error check.It is to utilize the principle of division and remainder to make error detection (Error Detecting), and the verification error detecing capability is strong, realizes easily, is to use one of the widest error-detecging code coded system at present.

The CRC method has two kinds of methods of calibration, step-by-step computing method and look-up table.The CRC code is simple though step-by-step is calculated, and shared internal memory is fewer, and its maximum shortcoming is exactly that position calculating can take processor resource.And the use look-up table can generate 16 CRC check code tables, and data operation quantity is little, and speed is fast.In the design, have under enough memory headroom situation at dsp chip, adopt look-up table to realize CRC, to optimize little process chip resource distribution.Following data are exactly the intact result of data check:

0xAA?0xFE?0x03?0x55?0x40?0x00?0xE9?0x01?0x00?0x33?0x5A?0xA0?0x150x25；

0xAA?0xFE?0x03?0x56?0x80?0x00?0x0F?0x02?0x00?0x39?0x0A?0x50?0x6A0xCD；

More than in two groups of data; Preceding 12 bytes are data, and 2 bytes that closely follow the back are check code, and receiving terminal is when receiving verification; The generator polynomial G (x) that adopts both sides to make an appointment removes the data that receive; Calculate, then result of calculation and actual reception to the remainder polynomid data compare, identical words represent that transmission is correct.

Should be successfully applied to the logger ground system based on the graceful Chester code Design of DSP, realize the communication function of ground system and down-hole bus termination.

The ground communications plate adopts USB interface to realize with communicating by letter of PC.Concrete ins and outs:

As shown in Figure 8; Selecting the EZ-USB FX2 family chip of Cypress company is intelligentized USB2.0 interface chip; Its integrated USB transceiver links to each other with the D-pin with the D+ of usb bus, can receive the data from main frame (Host), also can send data to main frame.

EZ-USB FX2 chip operation under this pattern, for external logic (the design's external logic is realized through FPGA), can be regarded FX2 as a FIFO under pattern in the design, and the sequential of read-write FIFO is provided by external logic.

Data/address bus, address bus and the control bus of 8051 single-chip microcomputer kernels all are connected to FPGA (Acex1K30) in the EZ-USB FX2 chip, can be provided with through the register relevant with A/D to the implementing reading and writing of assigned address (these registers are realized in FPGA).The FLAG of the interface section of EZ-USB FX2 is set to the full scale will and empty sign of EP2 and EP6 end points FIFO respectively; FPGA will be through inquiring about the store status that these indicate the Slave FIFO that obtains two exit points in the FX2 sheet, thereby carry out associative operation.The sequential of RDY is provided by FPGA, accomplishes the EP6 under the automatic input pattern is carried out write operation.

The above is merely the preferred implementation of the utility model, but the utility model protection domain is not limited thereto.Any those skilled in the art all can carry out suitable change or variation to it in the disclosed technical scope of the utility model, and this change or variation all should be encompassed within the protection domain of the utility model.

Claims (6)

1. the data transmission system in the oil logging tool is characterized in that, the down-hole collection plate is connected with the downhole telemetry plate through the CAN bus, and the downhole telemetry plate is connected through transformer coupled transmission means with the ground communications plate.

2. data transmission system as claimed in claim 1 is characterized in that, down-hole collection plate and downhole telemetry plate are provided with CAN isolates and driver module.

3. data transmission system as claimed in claim 2 is characterized in that, CAN isolates and comprises TMS320F2812 chip, ADuM1201 chip and the PCA82C250 chip that is connected in order with driver module, and the PCA82C250 chip inserts the CAN bus.

4. data transmission system as claimed in claim 2 is characterized in that the downhole telemetry plate comprises data processing module; The encoding process module; Decoding process module, modulation-demodulation circuit module and communication bus transformer, data processing module, encoding process module and decoding process module are realized by dsp chip; The modulation-demodulation circuit module is connected with the communication bus transformer with dsp chip respectively, and the communication bus transformer inserts the MIL-STD-1553B data/address bus.

5. data transmission system as claimed in claim 2 is characterized in that, the ground communications plate also is connected with PC through USB interface.

6. data transmission system as claimed in claim 5 is characterized in that the ground communications plate comprises the EZ-USBFX2 chip, and the EZ-USBFX2 chip is connected with the AcexlK30 chip.

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