DCTag SDK: dc_tag_read.c

DCTag SDK 1.2.1

This is an example of how to read tags in the DataCenter.
#include <memory.h>
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include "DCTag.h"
#define MAX_TAG_COUNT 100
int main ( int argc, char * argv[] )
{
 char ** tag_names;
 DC_TAG_HANDLE tag_handles[ MAX_TAG_COUNT ];
 DC_TAG tag_values[ MAX_TAG_COUNT ];
 int rc;
 int i;
 int retry;
 int tag_count = 0;
 
 if ( argc < 2 )
 {
 if ( !isatty( fileno( stdin ) ) )
 {
 // try to read the tag name from stdin
 char * line;
 size_t n;
 ssize_t len;
 
 tag_names = calloc( MAX_TAG_COUNT + 1, sizeof( char* ) );
 if ( NULL == tag_names )
 {
 printf( "alloc memory error!\n" );
 return -1;
 }
 
 do
 {
 line = NULL;
 n = 0;
 len = getline( &line, &n, stdin );
 if ( len > 1 )
 {
 while ( len > 1
 && ( line[ len - 1 ] == '\x0d' || line[ len - 1 ] == '\x0a' ) )
 {
 line[ len - 1 ] = 0;
 len--;
 }
 }
 if ( len > 0 )
 {
 tag_names[ tag_count++ ] = line;
 }
 } while ( len != -1 && tag_count < MAX_TAG_COUNT );
 }
 if ( tag_count <= 0 )
 {
 printf( "usage: dc_tag_read <tag_name> ...\n" );
 printf( " or echo \"<tag_name>\" ... | dc_tag_read\n" );
 printf( " or cat tag_list.txt | dc_tag_read\n" );
 printf( " or dc_tag_read < tag_list.txt\n" );
 return -2;
 }
 }
 else
 {
 tag_names = &argv[ 1 ];
 tag_count = argc - 1;
 }
 if ( argc > MAX_TAG_COUNT )
 {
 printf( "too many tag name specified, the max tag count is %d!\n", MAX_TAG_COUNT );
 return -3;
 }
 memset( tag_handles, 0, sizeof( tag_handles ) );
 memset( tag_values, 0, sizeof( tag_values ) );
 
 // initialize the DCTag SDK
 rc = dc_tag_init( MAX_TAG_COUNT, NULL, NULL );
 if ( rc != 0 )
 {
 printf( "dc_tag_init failed! error = %d\n", rc );
 return -4;
 }
 // prepare the tag handles
 for ( i = 0; i < tag_count; i++ )
 {
 tag_handles[ i ] = dc_tag_open( tag_names[ i ], NULL );
 if ( NULL == tag_handles[ i ] )
 {
 printf( "fail to open tag: %s\n", tag_names[ i ] );
 dc_tag_uninit();
 return -5;
 }
 }
 // read tags
 retry = 50;
 do
 {
 usleep( 100000 );
 rc = dc_tag_read( tag_handles, tag_values, tag_count );
 } while ( rc != 0 && retry-- );
 if ( rc != 0 )
 {
 printf( "fail to read tag value! error = %d\n", rc );
 for ( i = 0; i < tag_count; i++ )
 {
 dc_tag_close( tag_handles[ i ] );
 }
 dc_tag_uninit();
 return -6;
 }
 printf( "\n%-16s%-16s%-8s%s\n", "Tag Name", "Value", "Quality", "Time Stamp (UTC)" );
 printf( "--------------- --------------- ------- ---------------------------------------\n" );
 for ( i = 0; i < tag_count; i++ )
 {
 time_t tt = tag_values[ i ].time;
 struct tm * gmt = gmtime( &tt );
 printf(
 "%-16s%-16lf%04xH\t%04d-%02d-%02d %02d:%02d:%02d (%llu.%06u)\n",
 tag_names[ i ],
 tag_values[ i ].value,
 (uint16_t) tag_values[ i ].quality,
 1900 + gmt->tm_year,
 gmt->tm_mon + 1,
 gmt->tm_mday,
 gmt->tm_hour,
 gmt->tm_min,
 gmt->tm_sec,
 tag_values[ i ].time,
 tag_values[ i ].usec );
 }
 
 printf( "\n" );
 // close tag handles
 for ( i = 0; i < tag_count; i++ )
 {
 dc_tag_close( tag_handles[ i ] );
 }
 // uninitialize the SDK
 dc_tag_uninit();
 
 return 0;
}
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