dpExists()

The function dpExists() checks the existence of a valid datapoint identifier.

Synopsis

bool dpExists(string dpname);

Parameter

Parameter Description
dpname A datapoint identifier:

A sys, a DPT, a DP, a DPE, a config, a detail or an attr.

Return Value

The function returns true if at least one part of a datapoint identifier can be resolved correctly and otherwise FALSE.

Errors

The errors can be retrieved with getLastError(). This includes missing or incorrect arguments.

Description

The function dpExists() checks the existence of a valid datapoint identifier. The function returns true if at least one part can be resolved correctly, i.e. a sys, a DPT, a DP, a DPE, a config, a detail or an attr.

The following calls return TRUE:

dpExists(":_original.._value");
dpExists("System1:");
dpExists(":");
Note:
If you want to check for a dedicated part of the datapoint identifier such as DP name or DP+DPE, you must additionally call the function dpSubStr() with the appropriate enum parameter: bool e = dpExists(dpSubStr(ident2check, DPSUB_DP));

DP Identifier variable as an argument

dpExists() can also use a DP identifier variable as an argument. Note that CTRL does not have an explicit data type to store this type.

However, the type is received as part of a response to a dpQuery*() result - see example below:

main(mapping event)
{
  dpCreate("b1", "ExampleDP_Bit");
 
  dyn_dyn_anytype res;
  dpQuery("SELECT '_original.._value' FROM 'b1.'", res);
  DebugN(res);
  DebugN(dpExists(res[2][1]));
 
  dpDelete("b1");
 
  DebugN(res);
  string name = res[2][1];
  DebugN(dpExists(res[2][1]));
}

The example checks if the datapoint ExampleDP_Arg1 exists.

main()
{
 bool retVal;
 retVal = dpExists("System1:ExampleDP_Arg1");
 DebugN("dpExists:", retVal);
}

Assignment

Datapoint function

Availability

UI, CTRL