“Extended description by index” function
Index group: IdxGrp = 0x122300 + Channel ID
Index offset: IdxOffs = 0x4B
Extended | This function supplies extended information about the variable. The transferred data is dependent on the variable type. |
Transfer parameter (here with stream offset specified):
0 | 4 |
Variable index | Variable type identifier |
where
Contents | Type | Size |
Variable index | UNS32 | fixed, 4 bytes |
Variable type identifier | STRING | variable, max. 256 bytes |
=> stream length max. 260 bytes
Return value: (here with stream offset specified):
The return value is dependent on the variable type:
) V.G, V.A variables -> no return value since no extended description exists.
b.) V.E. variables:
0 | 4 |
Synchronisation | Validity range |
where
Contents | Type | Size |
Synchronisation | Enumeration (UNS32) 1 = NO_SYNC 2 = SYNCHRONISED | fixed, 4 bytes |
Validity range | Enumeration (UNS32) 1 = CHANNEL 2 = GLOBAL | fixed, 4 bytes |
=> stream length of V.E. Variable 8 bytes max. 2048 bytes
Notice
The variable type identifier, e.g. V.E, may not be followed by a dot.
Application examples
Example of reading the extended properties of a V.E. Variable:
Transfer parameters:
3 | V.E | 0 |
3 for the variable with index entry 3
V.E identifier of variable type: V.E
0 zero termination
Return values:
2 | 2 |
2 Synchronisation: SYNCHRONIZED
2 Validity range: GLOBAL