Easyarm i.mx287 Learning notes-controlling gpio via Modbus TCP

0 PrefaceThis paper uses the Freemodbus protocol stack to implement the Modbus TCP slave on the Easyarm i.mx287.

The coil registers are defined in the slave. The output of the Gpio can be controlled by the modbus instruction when the 4-bit and easyarm P2.4 to P2.5 are associated with the lower register address of the midline ring. This article changes from Freemodbus Demo sample linuxtcp. Simple changes are also available for other Linux development boards.

"Related blog posts""Easyarm i.mx28 Study notes--File IO mode operation Gpio" "Easyarm i.mx28 Learning notes-install and use tftp" "Raspberry Pi Study notes-realization Modbus RTU slave" "Modbus protocol Finishing-summary" "Freemodbus Modbus TCP Learning Note" "Modbus learning note--modbus TK modbus TCP host Implementation" "Linux learning Notes--Example Makefile Index blog post"
"Code Warehouse"The code warehouse is located in Bitbucket--easyarm-modbus-tcp, please use HG clone or download Zip package directly.

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1 part Code"Gpio-sysfs"Add enable Gpio, prohibit Gpio and GPIO periodic handler functions in Gpio-sysfs.

Among the gpio_poll, the input parameters are Modbus coil registers.

int gpio_enable (void) {    gpio_export (P24); gpio_direction (p24,out); Gpio_write (p24,0)    ; Gpio_export (P25); gpio_direction (p25,out); Gpio_write (p25,0)    ; Gpio_export (P26); gpio_direction (p26,out); Gpio_write (p26,0)    ; Gpio_export (P27); gpio_direction (p27,out); Gpio_write (p27,0)    ; return 0;} int gpio_disable (void) {    gpio_write (p24,0); Gpio_unexport (P24);    Gpio_write (p25,0); Gpio_unexport (P25);    Gpio_write (p26,0); Gpio_unexport (P26);    Gpio_write (p27,0); Gpio_unexport (P27);    return 0;} int Gpio_poll (unsigned char status) {    status & 0x01 Gpio_write (p24,1): Gpio_write (p24,0);    Status & 0x02? Gpio_write (p25,1): Gpio_write (p25,0);    Status & 0x04?
Gpio_write (p26,1): Gpio_write (p26,0);    Status & 0x08? Gpio_write (p27,1): Gpio_write (p27,0);    return 0;}

"Modbus poll"The Pvpollingthread thread obtains the coil register result--ucregcoilsbuf[0] and passes it to the Gpio_poll function.

void* pvpollingthread (void *pvparameter) {    esetpollingthreadstate (RUNNING);    if (embenable () = = Mb_enoerr)    {do        {            gpio_poll (ucregcoilsbuf[0]);//change IO Port status            if (Embpoll ()! = Mb_e NOERR) break                ;        }        while (Egetpollingthreadstate ()! = SHUTDOWN);    }    (void) embdisable ();    Esetpollingthreadstate (STOPPED);    return 0;}

"Coil register Read and write function"

EMBERRORCODEEMBREGCOILSCB (UCHAR * pucregbuffer, USHORT usaddress, USHORT usncoils, Embregistermode emode) {Emberrorco    De estatus = Mb_enoerr;    int incoils = (int) usncoils;       int usbitoffset;     if ((usaddress >= reg_coils_start) && (usaddress + usncoils <= Reg_coils_start + reg_coils_size))        {usbitoffset = (int) (Usaddress-reg_coils_start); Switch (emode) {case Mb_reg_read:while (Incoils > 0) {*PUCREGB uffer++ = Xmbutilgetbits (Ucregcoilsbuf, Usbitoffset, (UCHAR) (Incoils & Gt 8?                8:incoils));                Incoils-= 8;            Usbitoffset + = 8;                   } break; Case Mb_reg_write:while (Incoils > 0) {xmbutilsetbits (Ucregcoilsbuf, usbitoffs                    ET, (UCHAR) (Incoils > 8 8:incoils),           *pucregbuffer++);                Incoils-= 8;            Usbitoffset + = 8;        } break;    }} else {estatus = Mb_enoreg; } return estatus;}

    " Makefile "

# Specify Compiler cross = ARM-FSL-LINUX-GNUEABI-CC = $ (cross) Gccstrip = $ (cross) strip# Cflag contains header file Folder Cflags =-g-wall# header File Lookup Path inc =- I.-iport-i. /.. /modbus/rtu-i. /.. /modbus/ascii-i. /.. /modbus/include-i. /.. /modbus/tcp#libs =-lpthread# Destination target = modbustcp# source file src = demo.c gpio-sysfs.c port/portother.c port/portevent.c por T/porttcp.c. /.. /MODBUS/MB.C. /.. /modbus/tcp/mbtcp.c. /.. /MODBUS/FUNCTIONS/MBFUNCCOILS.C. /.. /modbus/functions/mbfuncdiag.c. /.. /modbus/functions/mbfuncholding.c. /.. /modbus/functions/mbfuncinput.c. /.. /modbus/functions/mbfuncother.c. /.. /MODBUS/FUNCTIONS/MBFUNCDISC.C. /.. The/modbus/functions/mbutils.c# source file is compiled to the destination file Objs = $ (SRC:.C=.O).  phony:clean# link to executable file $ (TARGET): $ (OBJS) $ (CC) $^-O [email protected] $ (LIBS) $ (STRIP) [email protected]# Can run files and target files clean:rm-f $ (OBJS) Rm-f $ (target) # Continuous action, first clear recompile link, copy to Tftpboot Install:clean $ (target) @echo copy to TFTPB Oot folder CP $ (TARGET) ~/tftpboot @echo Copy End # compilationRule add header file [email protected] on behalf of the target file $< represents the first dependent file%.o:%.c $ (CC) $ (CFLAGS) $ (INC)-O [email protected]-C $< 

2 Experiments"1" in virtual machine make get executable file--modbustcp "2" Configuration Easyarm IP address, for example Easyarm IP address is 192.168.1.211 ifconfig eht0 192.168.1.211 "2" via TF TP transfer can run files to the Development Board (if the IP address of the virtual machine is 192.168.1.106) tftp-g-R modbustcp 192.168.1.106 "3" To change the operational permissions.

and run

chmod a+x modbustcp./modbustcp "4" Modbus TCP has a simple console. Enter h to get instruction help. where e is the Enable protocol stack. Q is the exit program.

Enter e to enable Modbus slave protocol stack.
Figure 1 Running Modbus TCP
"5" opens the Modbus debugging software in Windows, connecting the Easyarm. The IP address is 192.168.1.211 and the port number is the default port number 205.

Figure 2 Controlling Gpio via Modbus TCP
Figure 3 Experimental results
4 Summary"1" Operation steps more, the realization of Modbus TCP requires a lot of basic knowledge.

Easyarm i.mx287 Learning notes-controlling gpio via Modbus TCP