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DCTag SDK
1.2.1
Copyright © 1983-2016 Advantech Co., Ltd.
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dc_tag_read_subscription.c
This is an example of how to read tags in the DataCenter by subscription.
#include <memory.h>
#include <stdio.h>
#include <stdlib.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 ];
void * subscr;
int rc;
int i;
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_subscription <tag_name> ...\n" );
printf( " or echo \"<tag_name>\" ... | dc_tag_read_subscription\n" );
printf( " or cat tag_list.txt | dc_tag_read_subscription\n" );
printf( " or dc_tag_read_subscription < tag_list.txt\n" );
return -1;
}
}
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 -2;
}
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 -3;
}
// 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 ] );
return -4;
}
}
// add subscription
subscr = dc_tag_add_subscription (
tag_handles,
tag_count );
if ( NULL == subscr )
{
// check error code here
printf( "fail to subscribe tags for read!\n" );
for ( i = 0; i < tag_count; i++ )
{
dc_tag_close( tag_handles[ i ] );
}
return -5;
}
// read tags
while ( 1 )
{
time_t current_time;
// clear the screen
system( "clear" );
// print current system time
current_time = time( NULL );
printf( "Current System Time: %s\n", ctime( ¤t_time ) );
// send read request
rc = dc_tag_read_subscription(
subscr,
tag_values,
tag_count );
if ( rc != 0 )
{
switch ( rc )
{
printf( "At least one given parameter is invalid!\n" );
break;
printf( "Connecting to the DataCenter\n" );
break;
printf( "Exception when allocation memory\n" );
break;
printf( "Fail to send request to the DataCenter\n" );
break;
printf( "The DataCenter return value count not equals to the request count\n" );
break;
printf( "The DataCenter return unexpected value type\n" );
break;
printf( "Fail to initialize the thread\n" );
break;
printf( "The input buffer size is too small\n" );
break;
printf( "The DataCenter is too busy to handle the request\n" );
break;
printf( "The SDK has not initialized\n" );
break;
default:
printf( "dc_tag_read_subscription return unknown error %d\n", rc );
break;
}
sleep( 1 );
continue;
}
// output tag values
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 );
}
sleep( 1 );
}
dc_tag_remove_subscription( subscr );
// close tag handles
for ( i = 0; i < tag_count; i++ )
{
dc_tag_close( tag_handles[ i ] );
}
// uninitialize the SDK
return 0;
}
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