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我嘗試使用，但沒有成功ARM：通過UART讀取MODBUS數據未能
機
- ARM板在ARM板上的UART連接來讀取一個RS485適配器寄存器：CM -T335 - TI AM335x嵌入式計算機模塊http://www.compulab.co.il/products/computer-on-modules/cm-t335/
- PC：x86機器運行Ubuntu
- 從設備：Elnet微微（能源電能表） - 可以作爲Modbus從站，併發送能量狀態到馬斯特R當使用Modbus協議請求http://elnet.feniks-pro.com/documents/User_manual/Elnet%20Pico%20-%20User%20Manual.pdf
連接器
- RX/TX電纜
- SENA RS485適配器：http://www.senanetworks.com/download/datasheet/ds_ltc100.pdf
- 男性 - 男性COM適配器：http://i.ebayimg.com/images/i/300758549547-0-1/s-l1000.jpg
- 超小型串行到DB9電纜：https://cdn3.yawarra.com.au/wp-content/uploads/Ultra-mini-serial-DB9-adapter_600x600.jpg
連接到ARM板
能源功率計< --rx/TX電纜從設備 - > SENA RS485適配器< --serial男/男性適配器+串行到迷你串行電纜 - > ARM板微型串行端口
看到設置的圖像：
- https://ibin.co/3CCvTVPPIUWQ.jpg
- https://ibin.co/3CCvhrr3CQjr.jpg
- https://ibin.co/3CCw5uNqTW8B.jpg
- https://ibin.co/3CCvuys1tUgt.jpg
設備樹中使用： am335x-SBC-t335.dts
設備樹資源：http://get-album.com/dts/
從屬設備連接到PC
能源功率計< --2線RX/TX - > SENA RS485適配器< - > PC
注：在板的微型串行端口是用於串行控制檯通信的相同端口（上波特115200） - 和這工作沒有問題
下面是AC碼，與使用libmodbus庫
libmodbus_test的讀取來自所連接的從動裝置中的第一寄存器中。Ç - 閱讀和打印來自該裝置的第一reigster：從在ARM板上運行libmodbus_test輸出]
[email protected]:~/new# gcc -I /usr/include/modbus/ libmodbus_test.c -o libmodbus_test -lmodbus
[email protected]:~/new# ./libmodbus_test /dev/ttyO0
created new rtu...
Opening /dev/ttyO0 at 9600 bauds (N, 8, 1)
ModBus connected !
[1F][03][00][01][00][02][96][75]
Waiting for a confirmation...
ERROR Connection timed out: select
#include <sys/types.h>
#include <string.h>
#include <modbus.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#define MODBUS_DEVICE "/dev/ttyS2"
#define MODBUS_STOP_BIT 1
#define MODBUS_DATA_BIT 8
#define MODBUS_START_BIT 1
#define MODBUS_PARITY 'N'
int main(int argc, char *argv[]) {
const char *dev_path = MODBUS_DEVICE;
uint16_t result[2];
int slave_nr = 31, baud = 9600;
modbus_t *mb;
if (argc == 2) {
dev_path=argv[1];
}
mb = modbus_new_rtu(dev_path, baud, MODBUS_PARITY, MODBUS_DATA_BIT, MODBUS_STOP_BIT);
if (mb == NULL) {
printf("error creating libmodbus rtu\n");
return -1;
}
printf("created new rtu...\n");
modbus_set_debug(mb, 1);
if (modbus_connect(mb) < 0){
printf("modbus error: %s\n", modbus_strerror(errno));
modbus_close(mb);
modbus_free(mb);
return -1;
}
modbus_set_slave(mb, slave_nr);
printf("ModBus connected !\n");
if (modbus_read_registers(mb, 0x1, 2, result) < 0) {
printf("error reading bits: %s\n", modbus_strerror(errno));
modbus_close(mb);
modbus_free(mb);
return -1;
}
printf("successfully red integer: %d: %X (hex)\n", result[0], result[0]);
modbus_free(mb);
return 0;
}
[輸出從在PC上運行libmodbus_test]
[email protected]:~/new# modbus gcc -I /usr/local/include/modbus libmodbus_test.c -o libmodbus_test -lmodbus
[email protected]:~/new# ./libmodbus_test /dev/ttyS2
created new rtu...
Opening /dev/ttyS2 at 9600 bauds (N, 8, 1)
ModBus connected !
[1F][03][00][01][00][02][96][75]
Waiting for a confirmation...
<1F><03><04><00><DD><00><DD><54><51>
successfully red integer: 221: DD (hex)
當從ARM板執行libmodbus_test時，在PC上運行相同的程序時select（）總是返回0 ，它工作得很好=>從設備返回數據。
使用的termios也未能得到相似的結果
termios_test.c
#include <sys/select.h>
#include <termios.h>
#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/types.h>
#include <string.h>
#include <stdint.h>
#include <linux/serial.h>
#include <sys/ioctl.h>
static const uint8_t table_crc_hi[] = {
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40,
0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1,
0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40
};
/* Table of CRC values for low-order byte */
static const uint8_t table_crc_lo[] = {
0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06,
0x07, 0xC7, 0x05, 0xC5, 0xC4, 0x04, 0xCC, 0x0C, 0x0D, 0xCD,
0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A,
0x1E, 0xDE, 0xDF, 0x1F, 0xDD, 0x1D, 0x1C, 0xDC, 0x14, 0xD4,
0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3,
0xF2, 0x32, 0x36, 0xF6, 0xF7, 0x37, 0xF5, 0x35, 0x34, 0xF4,
0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29,
0xEB, 0x2B, 0x2A, 0xEA, 0xEE, 0x2E, 0x2F, 0xEF, 0x2D, 0xED,
0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60,
0x61, 0xA1, 0x63, 0xA3, 0xA2, 0x62, 0x66, 0xA6, 0xA7, 0x67,
0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68,
0x78, 0xB8, 0xB9, 0x79, 0xBB, 0x7B, 0x7A, 0xBA, 0xBE, 0x7E,
0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71,
0x70, 0xB0, 0x50, 0x90, 0x91, 0x51, 0x93, 0x53, 0x52, 0x92,
0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B,
0x99, 0x59, 0x58, 0x98, 0x88, 0x48, 0x49, 0x89, 0x4B, 0x8B,
0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42,
0x43, 0x83, 0x41, 0x81, 0x80, 0x40
};
void calc_crc(uint8_t *buffer, ssize_t length, uint8_t *crc_hi_arg, uint8_t *crc_lo_arg) {
uint8_t crc_hi = 0xff;
uint8_t crc_lo = 0xff;
unsigned int i;
while (length--) {
i = crc_hi^*buffer++;
crc_hi = crc_lo^table_crc_hi[i];
crc_lo = table_crc_lo[i];
}
*crc_hi_arg = crc_hi;
*crc_lo_arg = crc_lo;
}
int main(int argc, char **argv){
char *dev_path = "/dev/ttyS2";
if (argc == 2) {
dev_path = argv[1];
}
uint8_t write_data[8];
int fd,write_len,select_ret, bytes_avail, status;
struct termios config;
char c;
uint8_t crc_hi, crc_lo;
fd_set activefs, tmpfs;;
struct timeval timeout;
timeout.tv_sec = 0;
timeout.tv_usec= 500000;
fd = open(dev_path, O_RDWR | O_NOCTTY | O_NDELAY | O_EXCL);
if (fd == -1){
perror("open");
return 1;
}
FD_ZERO(&tmpfs);
FD_SET(fd, &tmpfs);
printf("opened device\n");
if (tcgetattr(fd, &config) < 0) { close(fd); return -1 }
if (cfsetispeed(&config, B9600) < 0 || cfsetospeed(&config, B9600) < 0) {
printf("cant setting speed!\n");
close(fd);
return 1;
}
config.c_cflag |= (CREAD | CLOCAL);
config.c_cflag &=~ CSIZE;
config.c_cflag &=~ CSTOPB;
config.c_cflag &=~ PARENB;
config.c_cflag |= CS8;
config.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG);
config.c_iflag &= ~INPCK;
config.c_iflag &= ~(IXON | IXOFF| IXANY);
config.c_oflag &= ~OPOST;
config.c_cc[VMIN] = 0;
config.c_cc[VTIME] = 0;
if (tcsetattr(fd, TCSANOW, &config) < 0) {
printf("cant apply config!\n");
close(fd);
return 1;
}
write_data[0] = 0x1f; // slave addr
write_data[1] = 0x03; // function
write_data[2] = 0x00; // data address of first coil (8b)
write_data[3] = 0x01; // data address of first coil (8b)
write_data[4] = 0x00; // num of coils requested
write_data[5] = 0x01; // num of coils requested
calc_crc(write_data, 6, &crc_hi, &crc_lo);
write_data[6] = crc_hi;
write_data[7] = crc_lo;
printf("data: [0x%x][0x%x][0x%x][0x%x][0x%x][0x%x][0x%x][0x%x]", write_data[0], write_data[1], write_data[2], write_data[3], write_data[4], write_data[5], write_data[6], write_data[7]);
while (1) {
sleep(1);
write_len= write(fd, write_data, 8);
activefs = tmpfs;
select_ret = select(1, &activefs, NULL, NULL, &timeout);
if (select_ret < 0) {
perror("select");
return 1;
}
if (select_ret > 0) {
printf("select returned %d\n", select_ret);
if (read(fd, &c, 1) < 0) {
perror("read");
} else {
printf("received: %d\n", c);
}
}
}
}
[從termios.c輸出上ARM板]
[email protected]:~/new# ./termios /dev/ttyO0
opened device
嘗試...選擇不斷返回0
[從termios.c輸出的PC]
$ gcc -o termios_test termios_test.c
$ ./termios_test /dev/ttyS2
opened device
data: [0x1f][0x3][0x0][0x1][0x0][0x1][0xd6][0x74]select returned 1
received: 31
select returned 1
沒關係的價值觀，有一個數據交換，這就是我想用板
我試圖通過傳遞RS485了pcntl屬性要達到什麼，但同樣的結果發生 termios_rs485_test.c：http://pastebin.com/RWtHtjLF
板與PC之間的連接是通過超小型串行DB9電纜做，我可以成功地往返於板讀/寫數據。如何從RS485適配器讀取數據從未成功？我應該在哪裏尋找解決方案？
以下是有關板/驅動器的一些信息的/ etc
[email protected]:~/modbus# uname -a
Linux cm-debian 4.4.0-cm-t335-5.1 #98 SMP Thu Sep 1 15:12:31 IDT 2016 armv7l GNU/Linux
[email protected]:~/new# dmesg | grep -i --color '\(serial\|tty\|uart\)'
[ 0.000000] Kernel command line: console=ttyO0,115200n8 root=ubi0:rootfs rw rootfstype=ubifs ubi.mtd=rootfs
[ 0.771007] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 0.780286] omap_uart 44e09000.serial: no wakeirq for uart0
[ 0.780329] of_get_named_gpiod_flags: can't parse 'rts-gpio' property of node '/ocp/[email protected][0]'
[ 0.780960] 44e09000.serial: ttyO0 at MMIO 0x44e09000 (irq = 155, base_baud = 3000000) is a OMAP UART0
[ 1.543031] console [ttyO0] enabled
[ 1.550036] omap_uart 48022000.serial: no wakeirq for uart1
[ 1.556099] of_get_named_gpiod_flags: can't parse 'rts-gpio' property of node '/ocp/[email protected][0]'
[ 1.556764] 48022000.serial: ttyO1 at MMIO 0x48022000 (irq = 156, base_baud = 3000000) is a OMAP UART1
[ 2.953486] usb usb1: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[ 2.973176] usb usb1: SerialNumber: musb-hdrc.0.auto
[ 3.572722] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 6.689030] systemd[1]: Expecting device dev-ttyO0.device...
[ 7.210727] systemd[1]: Starting system-getty.slice.
[ 7.235407] systemd[1]: Created slice system-getty.slice.
[ 7.241302] systemd[1]: Starting system-serial\x2dgetty.slice.
[ 7.265277] systemd[1]: Created slice system-serial\x2dgetty.slice.
[ 7.925632] systemd[1]: Starting LSB: controls configuration of serial ports...
[ 8.485680] systemd[1]: Started LSB: controls configuration of serial ports.
[ 14.840532] pinctrl-single 44e10800.pinmux: pin 44e10978.0 already requested by 48022000.serial; cannot claim for 481cc000.can
[ 14.895866] pinctrl-single 44e10800.pinmux: pin 44e10980.0 already requested by 48022000.serial; cannot claim for 481d0000.can
[email protected]:~/modbus# setserial -a /dev/ttyO0
/dev/ttyO0, Line 0, UART: undefined, Port: 0x0000, IRQ: 155
Baud_base: 3000000, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal
[email protected]:~/new# setserial -a /dev/ttyS2
/dev/ttyS2, Line 2, UART: unknown, Port: 0x0000, IRQ: 0
Baud_base: 0, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal
[email protected]:~/new# setserial -a /dev/ttyS1
/dev/ttyS1, Line 1, UART: unknown, Port: 0x0000, IRQ: 0
Baud_base: 0, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal
[email protected]:~/new# setserial -a /dev/ttyS0
/dev/ttyS0, Line 0, UART: unknown, Port: 0x0000, IRQ: 0
Baud_base: 0, close_delay: 50, divisor: 0
closing_wait: 3000
Flags: spd_normal
[email protected]:~/modbus# lsmod
Module Size Used by
sha256_generic 9731 1
hmac 2866 1
drbg 13731 1
ctr 3673 2
ccm 7928 2
arc4 2000 2
wl12xx 57190 0
wlcore 180594 1 wl12xx
mac80211 605465 2 wl12xx,wlcore
cfg80211 492985 2 mac80211,wlcore
snd_soc_davinci_mcasp 15953 2
snd_soc_tlv320aic23_i2c 2092 1
snd_soc_simple_card 7474 0
snd_soc_tlv320aic23 10191 1 snd_soc_tlv320aic23_i2c
snd_soc_edma 1309 1 snd_soc_davinci_mcasp
snd_soc_core 158330 5 snd_soc_davinci_mcasp,snd_soc_edma,snd_soc_tlv320aic23_i2c,snd_soc_tlv320aic23,snd_soc_simple_card
snd_pcm_dmaengine 5548 1 snd_soc_core
snd_pcm 92743 4 snd_soc_davinci_mcasp,snd_soc_core,snd_soc_tlv320aic23,snd_pcm_dmaengine
c_can_platform 6650 0
c_can 9638 1 c_can_platform
wlcore_spi 5086 0
can_dev 12315 1 c_can
ti_am335x_adc 5635 0
snd_timer 21413 1 snd_pcm
kfifo_buf 3452 1 ti_am335x_adc
snd 55936 3 snd_soc_core,snd_timer,snd_pcm
industrialio 40286 2 ti_am335x_adc,kfifo_buf
evdev 13187 0
omap_wdt 5293 0
soundcore 1339 1 snd
[email protected]:~/new# cat /proc/cpuinfo
processor : 0
model name : ARMv7 Processor rev 2 (v7l)
BogoMIPS : 597.60
Features : half thumb fastmult vfp edsp thumbee neon vfpv3 tls vfpd32
CPU implementer : 0x41
CPU architecture: 7
CPU variant : 0x3
CPU part : 0xc08
CPU revision : 2
Hardware : Generic AM33XX (Flattened Device Tree)
Revision : 0000
Serial : 0000000000000000
[email protected]:~/new# cat /proc/consoles
ttyO0 -W- (EC p ) 250:0
[email protected]:/etc# cat debian_version
8.2
任何幫助十分讚賞 感謝
UPDATE
雖然連接超微型串行DB9電纜在電路板上，我運行了termios_test.c，在運行時，我在電纜的中間插入了一個金屬片（TX），我可以看到屏幕上顯示垃圾數據（有時！）。我把雄 - 雄適配器插入電纜並再次觸及中間的引腳，我可以再次看到垃圾數據。
我做的另一件事是將從屬設備連接到SENA RS485適配器，並在接觸金屬時使用適配器中間引腳的引腳上的金屬片使TX引腳開啓。沒有引腳會打開RX引導。將該RS485適配器連接到PC的COM端口時，將數據發送到該端口會使RX LED閃爍。我開始懷疑主板沒有正確寫入RS485適配器，或者引腳未正確映射。我應該從哪裏出發？這可能是一個真正的軟件問題嗎？
聽起來像systemd也在/ dev/ttyO0上啓動getty。內核參數使用ttyO0作爲內核控制檯。嘗試擺脫該配置 – nos
從bootargs中刪除了/ dev/ttyO0，但是這也不起作用，結果相同 – Smokie
您是否可以指向正在使用的設備樹文件？看起來你在ARM板上運行'CAN'（我猜不是在PC上），這些不同的協議可能會聲稱UART。一個基本的測試是連接一個環回電纜（或直接連接到一個PC機交叉）並運行mini-com等，看看你可以使用這個端口。你做到了嗎？這消除了你的代碼，設備電壓，linux/init配置等問題。分而治之總是不錯的。有很多層可能出錯，所以人們只能猜測。 –