Item naming convention

The SIDirect Communication Driver uses an item-naming convention based on the two-letter data-type identifiers used in programming the Siemens PLCs. The server accepts both the English and German standard identifiers.

The tables in this section describe the item naming convention for the Siemens S7-1500 PLCs. The ranges specified in those tables vary according to the type of the controller used.

Note: PDU (Protocol Data Unit) size is factored in determining Read/Write size limits. The S7-300 family of controllers can process PDU lengths of 480 to 960 bytes, depending on the controller. An S7-400 controller can process PDU lengths of 960 bytes.