An industrial controller having a number of addressable I/O modules, employs an I/O map table linking software addresses used for developing the control program to actual physical addresses of the I/O modules on a network. By employing software addresses for connection points to the control process, the program may be developed independent of the topology of the network connecting the processor to the I/O modules and changes in that topology may be made without affecting the control program, but simply by changing the I/O map table. A single change in the I/O map table re-connects an I/O module for all references in the control program.