1. An industrial control system, comprising: a plurality of I/O modules operable to interface with input devices and output devices on an industrial machine or process, the I/O modules communicating input I/O data representing the status of the input devices and output I/O data controlling the operation of the output devices; a scanner operable to exchange the I/O data with the I/O modules through a network, the scanner assembling the I/O data for a plurality of the I/O modules into a single optimized connection packet, wherein the I/O data for the plurality of I/O modules communicating with the scanner is arranged in a predetermined arrangement data block within the optimized connection packet, and wherein the I/O data is identified as to type and I/O module only by a relative location within the data block; and an industrial controller operable to exchange the optimized connection packet with the scanner, the industrial controller being further operable to store a control program including a plurality of cast tags, wherein each cast tag is referenced to a subset of the I/O data in the data block associated with a different single I/O module, and wherein each cast tag identifies a particular I/O module and includes a label for the data, a data type which is effective to characterize the I/O data for purposes of the executing the control program, and a reference to a location of the I/O data in the data block; wherein data for a particular I/O module may be accessed from the optimized connection packet by a programmatic reference of the cast tag at the industrial controller without communicating this information in the optimized connection packet.