Patent ID: 8155897

Claim:
A test apparatus that tests a device under test, comprising: a test unit that is electrically connected to the device under test and tests the device under test; a control section that controls the test unit; and a serial transmitting section that transmits transmission data back and forth between the control section and the test unit, wherein the serial transmitting section includes: a data sending section, provided on a transmission side, that sends a plurality of pieces of the transmission data in a predetermined order; a reception notifying section that, when a piece of the transmission data is received on a reception side, attaches identification data to an acknowledgement frame indicating that the piece of transmission data has been received, and sends the acknowledgement frame to the transmission side; a resending control section that, when a reception order of pieces of transmission data as indicated by the acknowledgement frames differs from the predetermined order, attaches resend count information, indicating whether a piece of the transmission data is resent data, to the pieces of transmission data beginning with the piece of transmission data that is received in the reception order differing from the predetermined order, and resends the pieces of transmission data to the reception side; and an expected acknowledgement ID storage section that stores an expected acknowledgement ID indicating the identification data that is expected to be attached to the acknowledgement frame received on the transmission side, the reception notifying section attaches, to the acknowledgement frame to be sent in response to the received piece of transmission data, the resend count information of the piece of transmission data, and sends the acknowledgement frame to the transmission side, and when the reception order of a piece of transmission data as indicated by the acknowledgment signal differs from the predetermined order, the resending control section does not resend the piece of transmission data if (i) the resend count information indicates that the piece of transmission data is resent data and (ii) the identification data attached to the acknowledgment signal is the same as the expected acknowledgement ID.