Siemens SIMATIC S5 Manual page 134

IP 265
Rules for referencing operands
Note
• Operands are specified with symbolic or direct addresses in the margin bars of the
control system flowchart. Inputs and outputs without identifiers ("open" input or
output) are identified by the text "????????". Open inputs are treated like
constants with a value of "0".
• The direct addresses of the IP 265's inputs and outputs are local, and may
therefore also appear in another IP 265's user program and in the CPU's user
program and have a different meaning.
• Identifiers (direct or symbolic addresses) for outputs and connectors cannot be
"written to" more than once in the IP 265 user program.
• Identifiers for IP 265 outputs are allowed in the output bar only. They cannot not
be directly scanned (remedy: distributor/connector).
• The extended inputs/outputs may be referenced as either input or output only (any
mix) in the IP 265 user program, i.e. in the control system flowchart, the user may
program e.g. either direct address I 2.3 or direct address Q 2.3, but not both
( Section 5.1.1).
• Either the fixed addresses of the expansion inputs/outputs or the fixed addresses
of the differential inputs may appear in the control system flowchart
( Section 5.1.1).
EWA 4NEB 812 6130-02a
Programming the IP 265 with COM 265
9-29