[ts-7000] Help with RS485 on 7200?

["whiffwaffle" <>]

I am having a heck of a time getting a simple Modbus command to work 
on the 7200. 

I can see the receive light flashing on the device, it just doesn't 
accept the command. I get no response at all.

The code I'm using is a stripped down version of the readmeter demo 
with some other changes I added while experimenting.

I'm using Modbus RTU devices (8-bit binary commands, not ASCII).

The device is set for 9600, N,8,1.

Here is the code I'm using:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#include <unistd.h>

#include <sys/types.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <assert.h>
#include <signal.h>

#include <time.h>

#include "ts_sbc.h"
#include "ioctls.h"

#define port485 "/dev/ttyAM1"
#define TIOC_SBCC485 _IOW('T',0x70,int) /*TS RTS/485 mode Clear*/
#define TIOC_SBCS485 _IOW('T',0x71, int) /*TS RTS/485 mode Set */

typedef unsigned char uchar;
typedef volatile unsigned char vuchar;

typedef uchar   bool;
#define TRUE    1
#define FALSE   0

int com;
struct termios options;

int openPort(char* port);
bool has485();
int init();
//-------------------------------------
bool has485(){
    uchar ccc;
    vuchar *chip;
    int fd;

    fd = open( "/dev/mem", O_RDWR );
    chip = (vuchar*)mmap( 0, getpagesize(), PROT_READ|PROT_WRITE,
                      MAP_SHARED, fd, 0x22c00000 );
    ccc = *chip;
    printf("mr=%d\n",ccc);

    chip = (vuchar*)mmap( 0, getpagesize(), PROT_READ|PROT_WRITE,
                                            MAP_SHARED, fd, 
0x22400000 );
    ccc = *chip;
    close( fd );
    return (ccc & 0x02) ? TRUE:FALSE;
}
//-------------------------------------
int openPort(char* port){
    int mcr;
    int err;
    
    if((com=open(port, O_RDWR | O_NOCTTY | O_NDELAY))!=-1){
        tcgetattr(com, &options);
        options.c_cflag=(CS8 | CLOCAL | CREAD);
        options.c_iflag=(IGNBRK | IGNPAR | IGNCR);
        options.c_oflag=OPOST;
        options.c_lflag=0;
        cfsetispeed(&options, B9600);
        cfsetospeed(&options, B9600);
        tcsetattr(com, TCSANOW, &options);

        tcflush( com, TCIFLUSH);
        
        printf("Setting mode    \n");
        mcr=AUTO485HD;  
        err=ioctl(com, TIOC_SBCS485, &mcr);
        if(err) 
            printf("err = %d\n", err);
    
        printf("Mode OK\n");
        return 0;
    }
    printf("OPEN FAILED!\n");
    return 1;
}
//-------------------------------------
int init(){
    if(has485())
        return openPort(port485);
    else
        return 1;
}
//-------------------------------------
int main(){
    int n,i;
    uchar buf[512];
    
    init();
//03/05/00/01/ff/00/dc/18   on
//03/05/00/01/00/00/9d/e8   off
    buf[0]=0x03;  //slave address 3
    buf[1]=0x05;  //force single coil
    buf[2]=0x00;  //coil #0001
    buf[3]=0x01;
    buf[4]=0xff;  //turn it ON (ff00)
    buf[5]=0x00;
    buf[6]=0xdc;  //crc hi
    buf[7]=0x18;  //crc lo
    for(n=0; n<10; n++){
        printf("\nWriting %d...\n",n);
        write( com, buf, 8);
        sleep(1);
    }
    sleep(1);
    memset(buf,0,512);
    read(com, buf, 512);   
    for(n=0;n<20;n++){
        printf("%d\n",buf[n]);
    }
    exit(0);
}

Any help would be greatly appreciated.



 
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