modbus_read_registers - read many registers

       The libmodbus documentation was written by Stéphane Raimbault <stephane.raimbault@gmail.com>

libmodbus v3.1.6                                   12/09/2019                            MODBUS_READ_REGISTER(3)

       The modbus_read_registers() function shall read the content of the nb holding registers to the address
       addr of the remote device. The result of reading is stored in dest array as word values (16 bits).

       You must take care to allocate enough memory to store the results in dest (at least nb *
       sizeof(uint16_t)).

       The function uses the Modbus function code 0x03 (read holding registers).

EMBMDATA
           Too many registers requested

           modbus_t *ctx;
           uint16_t tab_reg[64];
           int rc;
           int i;

           ctx = modbus_new_tcp("127.0.0.1", 1502);
           if (modbus_connect(ctx) == -1) {
               fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));
               modbus_free(ctx);
               return -1;
           }

           rc = modbus_read_registers(ctx, 0, 10, tab_reg);
           if (rc == -1) {
               fprintf(stderr, "%s\n", modbus_strerror(errno));
               return -1;
           }

           for (i=0; i < rc; i++) {
               printf("reg[%d]=%d (0x%X)\n", i, tab_reg[i], tab_reg[i]);
           }

           modbus_close(ctx);
           modbus_free(ctx);

       modbus_read_registers - read many registers

       The function shall return the number of read registers if successful. Otherwise it shall return -1 and
       set errno.

modbus_write_register(3) modbus_write_registers(3)

intmodbus_read_registers(modbus_t*ctx,intaddr,intnb,uint16_t*dest);