Communicating between a first device and a second device includes a first portion of the first device generating command mode control words for communication with the second device, a second portion different from the first portion converting the command mode control words into transport mode control words prior to transmitting the control words to the second device, the second portion of the first device receiving transport mode control words from the second device, the second portion of the first device converting the transport mode control words received from the second device into received command mode control words, and the second portion of the first device providing the received command mode control words to the first portion of the first device. The first portion of the first device may be an application running on the first device. The first and second devices may be coupled using a FICON connection.