Applies To:
  • CitectSCADA 5.xx, 6.00
  • CitectHMI 5.xx, 6.00

When using CitectSCADA OPC client driver with the RSLinx OPC Server, and attempting to write to an element in an array tag, the system crashes.
What could be causing this, and how do I avoid it?

The RSLinx OPC Server requires an additional notation in its address when referring to array tags.
If this notation is omitted, the RSLinx OPC Server will return an INT type rather than an INT array type.

The notation required is in the address is "Lxx". This indicates the total length (block size), or number of items to be read.

For example, ABIntegerArray!A[10] will not work - reads will always return 0, and
writes will crash, but ABIntegerArray,L10!A[10] will work.

This "Lxx" notation is documented in RSLinx. Please consult their help files
for more details. Note that this notation is only valid for RSLinx. Other OPC
servers don't need this notation.

crash, array tags, rslinx, opc