DR_ApReadPoint
DR_ApReadPoint — reads the value of a point.
Syntax
#include <cogent.h>
int DR_ApReadPoint( | char* | pnt_name, |
| | int* | pnt_type, |
| | DR_ApValue_t* | pnt_value, |
| | char** | error); |
Arguments
- pnt_name
- A
string containing the name of the required
point.
- pnt_type
- A
pointer to an integer to return the point type code. This is
needed to access the pnt_value. The
list of defined driver data point types is described in the
Overview section of the Device
Driver for Hilscher Fieldbus Cards manual. This parameter can
be NULL if the type of point is already
known.
- pnt_value
- A pointer to the memory area to receive the
point value. pnt_value is a union of
the different types, and pnt_type is
used to access the data.
- error
- The
address of a string pointer. In case of error (non-zero
return), the string pointer is set to the corresponding error
description string. The error string is contained in a static
buffer and remains valid only until the next API call. The
parameter may be NULL if no error string is
required.
Returns
The integer value
0 if the point was accessed successfully,
otherwise one of the following error codes is returned:
DR_ERR_PNT_NOT_FOUND
DR_ERR_PNT_NOT_ENABLED
DR_ERR_PNT_NOT_READABLE
DR_ERR_PNT_TYPE_NO_REP
DR_API_STATUS_ERRORS
DR_API_IPC_ERRORS
Description
This function reads the current value of the named point.
Example
int type, result;
DR_ApValue_t value;
char *error_str, *name = "Pushbutton";
result = DR_ApReadPoint (name, &type, &value, &error_str);
if (result == 0)
{
printf (" Pnt: %s ", name);
switch(type)
{
case DR_API_DOUBLE_TYPE:
printf ("(real) = %f\n", value.d);
break;
case DR_API_INT32_TYPE:
printf ("(int) = %d\n", value.i);
break;
case DR_API_INT16_TYPE:
printf ("(short) = %d\n", value.s);
break;
case DR_API_BIT_TYPE:
printf ("(bit) = %1X\n", value.s);
break;
default:
printf ("(%d) = %X\n", type, value.i);
}
}
else
printf (" Error@ListPoints:%s (%d, %s): \n",
name, result, error_str);
