我正在使用ARM板上的UART连接从RS485适配器读取寄存器,没有成功
机
> ARM板：CM-T335 – TI AM335x电脑模块http://www.compulab.co.il/products/computer-on-modules/cm-t335/
> PC：运行Ubuntu的x86机器
>从设备：Elnet Pico(能量功率计) – 作为一个模块从站,当使用modbus协议要求时,向主站发送能量状态http://elnet.feniks-pro.com/documents/User_manual/Elnet%20Pico%20-%20User%20Manual.pdf
连接器
> RX / TX电缆
> SENA RS485适配器：http://www.senanetworks.com/download/datasheet/ds_ltc100.pdf
>男 – 公COM适配器：http://i.ebayimg.com/images/i/300758549547-0-1/s-l1000.jpg
>超小型串口到DB9电缆：https://cdn3.yawarra.com.au/wp-content/uploads/Ultra-mini-serial-DB9-adapter_600x600.jpg
从设备连接到ARM板
能量功率计< - rx / tx电缆 - > SENA RS485适配器< - 串行公/公适配器串行到迷你串行电缆 - > ARM板迷你串口
查看设置图像：
> https://ibin.co/3CCvTVPPIUWQ.jpg
> https://ibin.co/3CCvhrr3CQjr.jpg
> https://ibin.co/3CCw5uNqTW8B.jpg
> https://ibin.co/3CCvuys1tUgt.jpg
使用的设备树：am335x-sbc-t335.dts
设备树资源：http://get-album.com/dts/
从设备连接到PC
能量功率计< - 2线rx / tx - > SENA RS485适配器个人计算机
注意：板上的迷你串口与串口控制台通讯使用的端口相同(波特率为115200),而且无任何问题
以下是使用libmodbus库从连接的从设备读取第一个寄存器的c代码
libmodbus_test.c – 从设备读取和打印第一个传送器：
#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; }
[从PC上运行libmodbus_test输出]
root@cm-debian:~/new# modbus gcc -I /usr/local/include/modbus libmodbus_test.c -o libmodbus_test -lmodbus root@cm-debian:~/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)
[从ARM板上运行libmodbus_test输出]
root@cm-debian:~/new# gcc -I /usr/include/modbus/ libmodbus_test.c -o libmodbus_test -lmodbus root@cm-debian:~/new# ./libmodbus_test /dev/ttyO0 created new rtu... opening /dev/ttyO0 at 9600 bauds (N,1) ModBus connected ! [1F][03][00][01][00][02][96][75] Waiting for a confirmation... ERROR Connection timed out: select
当从ARM板执行libmodbus_test时,select()始终返回0
在PC上运行相同的程序时,它工作正常=>从设备返回数据.
使用termios的尝试也失败了类似的结果
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[] = { 0x00,0xC1,0x81,0x40,0x01,0xC0,0x80,0x41,0x00,0x40 }; /* Table of CRC values for low-order byte */ static const uint8_t table_crc_lo[] = { 0x00,0xC3,0x03,0x02,0xC2,0xC6,0x06,0x07,0xC7,0x05,0xC5,0xC4,0x04,0xCC,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,0x44,0x84,0x85,0x45,0x87,0x47,0x46,0x86,0x82,0x42,0x43,0x83,0x40 }; 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,&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); } } } }
[从ARM板上的termios.c输出]
root@cm-debian:~/new# ./termios /dev/ttyO0 opened device
…选择继续返回0
[从PC上的termios.c输出]
$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
没关系的价值观,有一个数据交换,这就是我想用板子实现的
我尝试通过pcntl传递RS485属性,但是发生了相同的结果
termios_rs485_test.c：http://pastebin.com/RWtHtjLF
板和PC之间的连接通过超小型串行到DB9电缆完成,我可以从板上成功读取/写入数据.如何从RS485适配器读取数据从未成功？我应该在哪里寻找更贴近的解决方案？
以下是有关板/驱动程序等的一些信息
root@cm-debian:~/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
root@cm-debian:~/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/serial@44e09000[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/serial@48022000[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
root@cm-debian:~/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
root@cm-debian:~/new# setserial -a /dev/ttyS2
/dev/ttyS2,Line 2,UART: unknown,IRQ: 0
Baud_base: 0,divisor: 0
closing_wait: 3000
Flags: spd_normal
root@cm-debian:~/new# setserial -a /dev/ttyS1
/dev/ttyS1,Line 1,divisor: 0
closing_wait: 3000
Flags: spd_normal
root@cm-debian:~/new# setserial -a /dev/ttyS0
/dev/ttyS0,divisor: 0
closing_wait: 3000
Flags: spd_normal
root@cm-debian:~/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_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
root@cm-debian:~/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
root@cm-debian:~/new# cat /proc/consoles
ttyO0 -W- (EC p ) 250:0
root@cm-debian:/etc# cat debian_version
8.2
任何帮助都非常感激
谢谢
UPDATE
虽然超小型串行到DB9电缆连接到电路板,我运行termios_test.c,在运行时,我在电缆的中间插脚(TX)插入了一块金属片,我可以看到屏幕上显示的垃圾数据有时！).我将公头适配器插入电缆,再次触摸中间的针脚,我可以再次看到垃圾数据.
我所做的另一件事是将从设备连接到SENA RS485适配器,并在接触金属时使用插针上的金属片,适配器的中间插针,使TX LED导通.没有引脚会打开RX引线.将RS485适配器连接到PC的COM端口时,将数据发送到该端口将使RX LED闪烁.我开始怀疑该主板没有正确地写入RS485适配器,或者该引脚没有正确映射.我应该从哪里走？这可能是真的软件问题吗？
解决方法
termios_test.c中有两个软件问题.第一个问题是与错过的tcgetattr()相关.第二个是第一个参数选择()必须是1,而不是fd 1.现在他们修复,代码仍然不能与SENA RS485一起工作.
无框噪声建议将ARM板连接到PC,并检查ARM板上的UART是否正确配置. Smokie连接ARM到PC使用超小型串行到DB9电缆,并确认termios_test.c可以发送和接收数据到Windows PC.
现在我假设的问题是ARM与SENA的物理连接.用于将ARM连接到PC的超小型串行到DB9电缆是可交叉的.它将ARM RX引脚连接到PC TX引脚,反之亦然. SENA RS485适配器直接连接到PC,无需任何电缆.它有直接的连接：PC TX引脚连接到SENA TX引脚和PC RX引脚连接到SENA RX引脚. ARM使用超小型串行到DB9电缆和公公COM适配器连接到SENA.公 – 公COM适配器不更改引脚顺序,因此TX引脚变为TX引脚.所以在连接到SENA RX引脚的ARM TX引脚连接错误.
为了进行原理图的工作,必须使用COM零调制解调器电缆,而不是使用Male – Male COM适配器.它的基本引脚可能如下：
ARM side SENA side
TXT pin 3 <--> RXD pin 2
RXD pin 2 <--> TXT pin 3
GND <--> GND
RTS pin 7 (leave unconnected) +-> RTS pin 7
|
CTS pin 8 (leave unconnected) +-> CTS pin 8
|
DTR pin 4 (leave unconnected) +--> DTR pin 4 (to emulate the same behavior as PC does)
DCD pin 1 (leave unconnected) (leave unconnected) DCD pin 1
DSR pin 6 (leave unconnected) (leave unconnected) DSR pin 6
如果SENA使用硬件流量控制,则RTS和DTR输入必须连接到CTS输出.如果没有,他们可能没有连接.我建议先连接RXD,TXD和GND信号,如果不行,连接RTS,CTS和DTR引脚.
可以将RTS和CTS引脚连接到ARM,以实现硬件流控制,但这并不能说明.因为SENA RS485 TX / RX速度与UART速度相同.无论如何,应进行以下更改：安装R44和R45(不安装在ARM板上),并修改ARM板DTS文件(现在用作I2C1引脚)中的RTS / CTS引脚,并在软件中设置UART以使用流控制.
如果有人在ARM上声明UART,您将在数据流中看到意外的字符(例如,如果ARM使用UART0作为控制台,则会在ARM引导期间看到SENA TX引脚闪烁).或者如果使用UART的getty,您将看到数据流中的“登录名”或“登录不正确”.此外,ARM引导ROM还可以将一些字符串打印到UART中,并且不能禁用该行为. U-boot可能会使用UART作为控制台并输出横幅字符串.准备好这样的数据将进入RS485,并以某种方式影响其工作.
