GE PACSystems RX7i

Chapter 3. Program Data
GFK-2950C February 2018 35
Dimensional support:
▪ One-dimensional (1D) formal parameter arrays in the logic of a UDFB or parameterized block
▪ 2D support for the top level of an array of structures and 1D support for a structure element
that is an array. For example:
PQR[a, b].STRU[y].Zed,
where Zed is an element of the array of structures STRU, which itself is an element of the 2D
array of structures PQR.
▪ 1D and 2D arrays for other variables
Other features:
▪ An array with a variable index supports a bit reference, for example
MyArray[nIndex].X[4],
where .X[4] is the fifth bit of the value stored in MyArray[nIndex]. The bit reference itself, [4]
in the example, must be a constant.
▪ In LD, the following word-for-word changes are supported for array elements with variable
indexes:
Replacing an index variable with another index variable
Replacing an index variable with a constant
Replacing a constant with an index variable
In LD, Diagnostic Logic Blocks support the use of array elements with variable indexes.
Where Array Elements with Variable Indexes are Not Supported:
The following do not support array elements with variable indexes:
▪ Indirect references
▪ EGD variables
▪ Reference ID variables (RIVs) and I/O variables when accessed in the Hardware Configuration
Note: In logic, RIVs and I/O variables support variable indexes.
▪ STRING variables
A variable index cannot be one of the following:
▪ A math expression. For example, ABC[GH+1] is not supported.
▪ An indirect reference. For example, W[@XYZ] is not supported.
▪ A bit reference. For example, ABC[DEF.X[3]] is not supported.
Note: You can use a bit reference on an array element designated by a variable index. For example,
ABC[DEF].X[3] is supported.
▪ An array head. For example, if MNP and QRS are arrays, MNP[QRS] is not supported, but
MNP[QRS[3]] and MNP[QRS[TUV]] are, where TUV is an index variable.
▪ A negative index. This generates a run-time non-fatal CPU fault.
▪ A value greater than Y, where Y = [number of array elements] - 1. This generates a run-time non-
fatal CPU fault.