A method includes determining a scan rate associated with each of a plurality of input/output (I/O) modules. The method also includes transmitting a read request message to at least one expansion controller that controls the plurality of I/O modules, the read request message having an align index field. The method further includes receiving a reply message from the at least one expansion controller for each of the I/O modules for which a value of the align index field of the read request message is an even multiple of the associated scan rate. The method also includes incrementing the value of the align index field. In addition, the method includes repeating the transmitting, receiving, and incrementing until the value of the align index field is greater than a threshold, wherein the threshold is a least common multiple of the scan rates of the plurality of I/O modules.