A transaction controller orders transactions between a master device and a slave device, where the transactions may be received out-of-order. First and second transactions have respective first and second sets of data packets. The transaction controller includes a transaction table, a first ordering counter, and a first sequence counter having first and second values when the first and second transactions are initiated. The first and second values are stored in the transaction table based on first and second transaction identifiers (TIDs) that are associated with the first and second transactions. The transaction controller determines, based on the second value, the second TID, and a current value of the first ordering counter, whether the first and second sets of data packets were received out-of-order. Based on the determination, the second set of data packets is transmitted to the master device after the first set of data packets.