Abstract: An interface between a network communication card and an industrial controller allows rapid asynchronous buffering using two buffers and two associated registers for each data direction. A reading of the buffers is proceeded by an attempt to copy from the write designation register to the read designation register checking the equality of the register values and then reading from the buffer designated by their common value. Conclusion of the reading sets the write destination register to zero. Writing of the buffers is proceeded by a checking of the read designation register for zero value and then writing to other than the last buffer indicated by the write designation register. If the read designation register is non-zero, then the writing occurs to the opposite buffer of that in the read designation register. The write designation register is then updated to indicate the buffer written to.