CN201122987Y - GPRS-RS485 gateway based on ARM7CPU core - Google Patents

Abstract

The utility model discloses a GPRS-RS485 gateway based upon an ABM7CPU nucleus, wherein the industrial scale MC35 of Siemens is selected as the GPRS module and the A T91SAM7A3 as the CPU module. Because UART and the other communication interfaces are integrated in the CPU and the resources are abundant in FLANSH and RAM, the TCP\IP protocol stack can be embedded without expanding resources, thereby the complexity of circuit is avoided, the cost is reduced, and simultaneously the anti-interference ability is strengthened.

Description

GPRS-RS485 gateway based on ARM7CPU nuclear

Technical field

The utility model relates to the network control based on GPRS wireless network and RS485 industrial field bus, is mainly concerned with a kind of novel GPRS-RS485 gateway from the industry spot remote data acquisition of being used for based on ARM7CPU.

Background technology

In recent years along with the fast development in industrial automation field, industrial field bus is because its reliability height, cost is low, failure rate is low etc., and advantage makes it use more and more widely, consideration for cost and communication performance, the RS485 bus is occupied very big proportion in industrial field bus, especially in field of track traffic such as railway locomotive, light rail, subways, the application of RS485 bus is very extensive.Along with the informationalized construction of China railways, remote monitoring for rail vehicle also becomes the current problem that we need urgently solve, before the large-scale GSM-R network in the whole nation builds up, use GPRS network to be transferred to ground, become the preferred option that most current cost is low, realization is fast, reliability is high from the data wireless of rolling stock collection in worksite.The design is exactly at this application, has adopted ARM7CPU to design a kind of low cost, high performance GPRS-RS485 gateway.

RS-232, RS-422 and RS-485 are worked out and issue by Electronic Industries Association (EIA) at first.RS-232 is issue in 1962, as industrial standard, to guarantee the compatibility between the different manufacturers product.RS-422 is that it proposes for the deficiency that remedies RS-232 by the RS-232 development.EIA has formulated the RS-485 standard in nineteen eighty-three again on the RS-422 basis; multiple spot, two-way communications capabilities have been increased; promptly allow a plurality of transmitters to be connected on same the bus, increased the driving force and the conflict defencive function of transmitter simultaneously, expanded the bus common mode range.

The RS485 data-signal adopts differential transfer mode (Differential Driver Mode), be also referred to as balance transmission, it uses a pair of twisted-pair feeder, wherein a line is defined as A, another line is defined as B, generally, the positive level between transmitter A, the B+2～+ 6V, be a logic state; Negative level-2～-6V, be another logic state, other has a signal ground C.In the RS-485 device, generally also has " an enabling " control signal." enable " signal and be used to control the cut-out that sends transmitter and transmission line and be connected, when " enabling " end works, send transmitter and be in high-impedance state, be called " elicit illness state ", it is the third state that is different from logical one and " 0 ".The maximum transmission distance of RS-485 standard is about 1219 meters, and peak transfer rate is 10Mbps.Usually, RS-485 network using balancing twisted-pair line is as transmission medium, and the length and the transmission rate of balancing twisted-pair line are inversely proportional to.In general, 15 meters long twisted-pair feeder peak transfer rates are 1Mbps.

The RS-485 standard is often used as to a kind of relatively economical, have that suitable strong noise suppresses, the communications platform of high relatively transmission rate, long transmission distance, wide common mode range, therefore, RS485 has obtained extensive use in fields such as Industry Control, power communication, intelligence instrument, security protection, track traffic.

GPRS is that the English of GPRS (General Packet Radio Service) is called for short, and is a kind of new data loading service that development is come out on existing gsm system, and purpose is the data service that block form is provided for GSM user.GPRS adopts packet-switch technology, and message transmission rate is up to 160Kbps.The basic process of packet switching is that data are divided into several little packets earlier, can deliver to destination in the relay mode that storage is transmitted, and be assembled into complete data by different routes.Packet switching is not real-time system basically, and time-delay is unfixing yet, but can make different transfer of data " shared " transmission bandwidth: the data occupancy bandwidth is arranged, do not take during free of data, thereby share resource.Adopt the GPRS of the packet switching wireless channel of then can applying in a flexible way, each user can have a plurality of wireless channels, and same channel can be shared by several users, thereby has greatly improved utilization ratio of wireless resources.GPRS adopts the wireless-modulated standard same with GSM, same frequency band, same burst structure, same frequency hopping rule and same tdma frame structure, and this new Packet Data Channel is extremely similar to current Circuit-switched voice service channel.Therefore, existing base station sub-system (BSS) can provide comprehensive GPRS to cover from the beginning.GPRS allows the user to transmit and receive data under end-to-end packet transfer mode, and does not need to utilize the Internet resources of circuit switched mode.Thereby provide a kind of efficiently, wireless packet data service cheaply.That be specially adapted to be interrupted, paroxysmal and frequent, a spot of transfer of data also are applicable to big data quantity transmission once in a while.Because GPRS allows the user to transmit and receive data under packet switched mode, thus provide a kind of efficiently, wireless packet data service cheaply.

The ARM7CPU model is AT91SAM7A3, is the AT91 of atmel corp series A RM microprocessor, and inside has 256K byte high speed Flash, 32K byte high-speed SRAM, the MMC interface, 2 SPI mouths, 3 UART, the DMA of 2 serial CAN bus communication interfaces, 19 passages, 9 timers, 1 cycle intervalometer, backup battery module, house dog, 8PWM, 16 path 10 position ADC, the high drive pin, POR, crystal oscillator, RC oscillator on the sheet, PLL, senior clock and power management single-ended 3 is to the 3.6V power supply.Because this CPU has 3 UART mouths, can use UART0 and GPRS module communication, use the communication port of UART1 as RS485, use the communication port of UART2, so use this CPU for realizing that the GPRS-RS485 gateway is very convenient as RS232.

Summary of the invention

The utility model has been researched and developed a kind of compatible high, novel in design, strong GPRS-RS485 gateway that is used for remote data transmission of flexibility at the problem of present existence.Technical solution of the present utility model is achieved in that

A kind of GPRS-RS485 gateway based on ARM7CPU nuclear, comprise power module, indicating lamp module and sim card socket interface module, it is characterized in that also comprising CPU module that constitutes by AT91SAM7A3 and the GPRS module that constitutes by MC35, CPU module and GPRS module are directly powered by power module, and the GPRS module then is connected with the sim card socket interface module; Wherein said CPU module is embedded cut out version ICP/IP protocol stack and integrated two independent CAN controller and three UART mouths, in the described UART mouth UART0, UART1 and UART2 are arranged, wherein the PD holding wire of the 15 pin IGT of UART0 and 31 pins is controlled the startup of GPRS module and is stopped; The SYNC of 32 pins is a synchronizing signal, is used for controlling the flicker of GPRSLED indicator light; The 16-23 pin links to each other with six I/O mouths of CPU, sends the work that AT instructs control module by CPU to the GPRS module; The UART1 mouth is as the communication port of RS485, receive respectively by RXD1 and TXD1 on the RO and DI pin of transceiver MAX485 of RS485, form A, B two paths of differential signals by processing of circuit in it, handle through filtering and protection, the two paths of signals line is inserted the DB9 port, guide to the outside and RS485 network communication use of gateway, the PO mouth is as the enable signal of MAX485 simultaneously; UART2 receives the R of the transceiver MXA232 of RS232 respectively as outside RS232 interface by RX2 and TX2 ₂Out and T ₂On the pin of in, in it, insert the DB9 port behind the circuit, be used for the h.323-configured gateway parameter.

Compare with the mode of remote transmission data such as traditional use radio station or WLAN, use GPRS to have remarkable advantages:

1, need not build special wireless network, not have the capital construction expense, the project implementation is quick;

2, it is cheap not need to purchase expensive equipment, operation cost;

3, fast, the signal stabilization of data transmission bauds, be not subjected to the restriction of region and weather;

4, the position at ground monitoring station is not subjected to regional impact yet, as long as can insert Internet.

Description of drawings

The utility model has 8 accompanying drawings, wherein:

Fig. 1 wireless supervisory control system fundamental diagram;

Fig. 2 GPRS-RS485 gateway structure chart;

Fig. 3 ARM7 and RS485, RS-232 interface circuit;

Fig. 4 sim card socket interface circuit;

Fig. 5 GPRS module interface circuit;

Fig. 6 DC24V changes the DC5V interface circuit;

Fig. 7 DC5V changes the DC3.3V interface circuit;

Fig. 8 GPRS-RS485 gateway communication process flow chart.

In the drawings: 1, ground surveillance terminal, 2, fire compartment wall, 3, the Internet server, 4, CGSN gateway, 5, antenna, 6, the GPRS-RS485 gateway, 7, power module, 8, GPRS module, 9, SIM card, 10, CPUAT91SAM7A3,11, RS-485,12, RS-232,13, the LED light module, 14, the GSM network.

Embodiment

As Fig. 1-GPRS-RS485 gateway based on ARM7CPU nuclear shown in Figure 7, it is characterized in that comprising high-grade cpu controller AT91SAM7A3, GPRS module and peripheral circuit, RS485 interface circuit, described GPRS-RS485 gateway is responsible for the mutual of RS485 network and GPRS network data flow, the data flow of gathering on the industry spot RS485 bus is transferred to the ground remote supervisory station by GPRS, give remote computer and use, realize supervision the long-range RS485 network equipment; Be the RS485 network that remote computer can send instructions to industry spot on the other hand, finish Long-distance Control the RS485 network equipment.Described GPRS module receives GPRS packet datagrams bag on the one hand by radio-frequency antenna from the GSM network, through protocol translation, the frame head postamble that removes the GPRS datagram forms the IP packet, and this packet is transferred to central processor CPU by the RS232 interface; Receive the IP packet that CPU sends on the other hand, carry out protocol translation and be packaged into the GPRS packet and send to the GSM network through radio-frequency antenna; Central processor CPU AT91SAM7A3 carries out data forwarding between RS485 network and GPRS network, finish protocol translation simultaneously.Because we use the communication port of the UART1 mouth of AT91SAM7A3 as RS485, so AT91SAM7A3 can finish the transmitting-receiving of RS485 network data by the RS485 transceiver that joins with it, AT91SAM7A3 another one important function is to finish the packing of TCP IP packet and unpack, also be responsible for simultaneously providing of monitoring voltage, dongle, working power.Below some emphasis circuit in the working mechanism of whole monitoring system and the utility model are elaborated.

GPRS-RS485 gateway image data from the RS485 network of locomotive or fieldbus as shown in Figure 1, radio-frequency antenna through the GPRS-RS485 gateway sends to the form of data with the GPRS packet data package in the GSM network then, data arrive behind the GSM network through the CGSN gateway carries out protocol conversion with in the station server of transfer of data to the Internet, the any computer that inserts Internet in ground can be as monitor terminal like this, visit the data that the collection of GPRS-RS485 gateway comes by the Internet access server, equally also can will pass in the RS485 network under the instruction.

As shown in Figure 2, the GPRS-RS485 gateway mainly comprises following a few part from hardware circuit: power unit, GPRS module, SIM socket, central processing unit AT91SAM7A3, RS485 communication port, RS-232 communication port, LED light part comprise power supply indicator POWER LED, RS485 indicator light RS485LED, GPRS indicator light GPRS LED.

Power unit is used for providing the power supply of DC 3.3V and 5V to central processing unit and GPRS module for power supply;

The GPRS module mainly is to be used for receiving the IP packet from central processing unit AT91SAM7A3, after protocol conversion is packaged into the GPRS packet data package, data are sent to the GSM network, will separate from the GPRS packet that the GSM network receives simultaneously and send to central processing unit AT91SAM7A3 after being bundled into the IP packet;

The SIM socket is used for installing SIM card, and the GPRS module has only the authentication by SIM card could insert the GSM network;

Central processing unit AT91SAM7A3 is the core component of whole GPRS-RS485 gateway, AT91SAM7A3 will carry out the data of receiving from the RS485 bus interface ICP/IP protocol conversion, pack the data to the IP packet and send to the GPRS module, from the GPRS module, receive the IP packet simultaneously, the data after unpacking are sent on the RS485 bus.Because we have embedded the ICP/IP protocol stack after the cutting in AT91SAM7A3, so just can finish unpacking of TCP/IP and packing work by AT91SAM7A3.AT91SAM7A3 also needs to receive configuration data to the GPRS-RS485 gateway from the RS232 mouth, and configuration information can be stored among the FLASH, can accomplish that power down do not lose configuration data, and each GPRS-RS485 gateway powers on and reads configuration information automatically.AT91SAM7A3 possesses functions such as house dog simultaneously, can system automatically reset when fortuitous event appears in gateway.

The RS485 communication port is mainly used to AT91SAM7A3 is inserted the RS485 network, receives data and send data from the RS485 network in the RS485 network.

The RS-232 communication port mainly is the open user of giving, and the user can use RS-232 mouth and the communication of GPRS-RS485 gateway in the PC, finishes the configuration to some operational factors of GPRS-RS485 gateway.

LED light partly is used to refer to the operating state that the GPRS-RS485 gateway is shown, and when GPRS-RS485 gateway normal power supply, the POWER LED light can be shinny; Marquis RS485LED indicator light can glimmer when from RS485 network transceive data; The GPRS LED light is used to refer to the operating state of GPRS module, and this indicator light can be indicated with different flicker frequencies when the GPRS module was in different operating state such as initialization, Network Search, transceive data.

As shown in Figure 3, what ARM7 CPU AT91SAM7A3 used is the crystal oscillator of 18.432M, and the operating voltage of chip is 3.3V.67,68,69,70 pins are the JTAG emulator interface, and its circuit connects as shown in the figure, and interface uses the JTAG socket of 20 pins.The UART1 mouth of AT91SAM7A3d is as the communication port of RS485; RXD1 and TXD1 are connected respectively on the RO and DI pin of RS485 transceiver MAX485; form A and B two paths of differential signals line by MAX485; handle through the filtering protection; this two paths of signals line is guided to the outside and RS485 network communication use of gateway by the DB9 interface, use the enable signal of P0 mouth simultaneously as MAX485.Inner integrated three the UART mouths of knowing clearly of AT91SAM7A3, we use UART0 mouth and GPRS module communication, use UART2 to be used for the h.323-configured gateway parameter as outside RS232 interface, owing to need handshake with the GPRS module communication, so we use PA6, PA7, PA18, PA19, six IO mouths of PA20, PA21 to make six signal wire interfaces of RTS0, CTS0, RING0, DTR0, DCD0, DSR0 of UART0.The RS232 mouth does not need handshake, so we only get final product with RX2 and the TX2 transceive data of UART2, still is used for and external communication owing to this RS-232 mouth, so need to use MAX232 to be used as the transceiver of this 232 interface.

As shown in Figure 4, sim card socket is used for directly linking to each other with the GPRS module, comprises that the power supply to SIM card is all provided by the GPRS module, no longer to its independent power supply.SIM socket one has 8 pins, wherein CCVCC is used for powering, directly be connected with the CCVCC pin of GPRS module, GND ground connection, CCIO is a serial data line, the transmission of control data and reception, CCDET1 and CCDET2 are used for detecting SIM and whether are inserted in socket, CCDET1 is used for powering, CCDET2 connects to high level when SIM inserts socket, does not have SIM to be inserted as low level, and the CCIN pin of CCDET2 and GPRS module links to each other, CCCLK is provided with the clock cable of SIM card for the GPRS module, and CCRST is the SIM card reseting signal line.

The GPRS module that we select for use is the MC35 of Siemens Company, and this module provides the communication interface of ZIF 40 pins, wherein 1,2,3,4,5 pins power supply; 6,7,8,9,10 pin ground connection; 11,12 pins are used for connecting reserve battery; The PD holding wire of the IGT of 15 pins and 31 pins is used for controlling the startup of GPRS module and quitting work, the IO mouth of these two pins and AT91SAM7A3 links to each other, 8 road holding wires of 16 to 23 pins and the UART0 of AT91SAM7A3 are connected, and send the work that AT instructs control module by AT91SAM7A3 to the MC35 module; The SYNC of 32 pins is a synchronizing signal, by the flicker situation of this signal controlling GPRS LED light.8 road holding wires of 33 to 40 pins are used for connecting the voice handle, because we do not use the voice handle, so this several signals line is unsettled just passable.

In field of track traffic, locomotive, light rail etc. generally can only provide DC24V power supply, so the operating voltage of this gateway designs is DC24V, yet because the operating voltage of intra-gateway chip is DC5V and DC3.3V, transforms so will carry out voltage at intra-gateway.The DC24V power supply that inserts for the outside is converted into DC5V by the ZUS152405 module, and DC5V is converted into 3.3V by the AS1117M3-3.3V module again, and whole system is used DC5V and DC3.3V work.

Claims (2)

1. GPRS-RS485 gateway based on ARM7CPU nuclear, comprise power module (7), indicating lamp module (13) and sim card socket interface module (9), it is characterized in that also comprising CPU module (10) that constitutes by AT91SAM7A3 and the GPRS module (8) that constitutes by MC35, CPU module and GPRS module are directly powered by power module, and the GPRS module then is connected with the sim card socket interface module; Wherein said CPU module is embedded cut out version ICP/IP protocol stack and integrated two independent CAN controller and three UART mouths, in the described UART mouth UART0, UART1 and UART2 are arranged, wherein the PD holding wire of the 15 pin IGT of UART0 and 31 pins is controlled the startup of GPRS module and is stopped; The SYNC of 32 pins is a synchronizing signal, is used for controlling the flicker of GPRSLED indicator light; The 16-23 pin links to each other with six I/O mouths of CPU, sends the work that AT instructs control module by CPU to the GPRS module; The UART1 mouth is as the communication port of RS485, receive respectively by RXD1 and TXD1 on the RO and DI pin of transceiver MAX485 of RS485, form A, B two paths of differential signals by processing of circuit in it, handle through filtering and protection, the two paths of signals line is inserted the DB9 port, guide to the outside and RS485 network communication use of gateway, the PO mouth is as the enable signal of MAX485 simultaneously; UART2 receives the R of the transceiver MXA232 of RS232 respectively as outside RS232 interface by RX2 and TX2 ₂Out and T ₂On the pin of in, in it, insert the DB9 port behind the circuit, be used for the h.323-configured gateway parameter.

2. the GPRS-RS485 gateway based on ARM7CPU nuclear according to claim 1 is characterized in that the external DC24V power supply of described power module, is converted into DC5V and/or is converted into 3.3V by the AS1117M3-3.3V module by the ZUS152405 module.

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