JTAG test equipment arranged to establish an asynchronous data transmission connection with a JTAG-compatible device under test for the transmission of test data between test access ports (TAP) in the test equipment and device under test. The test data is synchronized at reception before the test access ports (TAP). The test equipment includes a computer program for adapting a test data sequence arriving in the format defined by the test access port for transmission on an asynchronous transmission path, and a transceiver (TR1) for adapting the test data sequence and transmitting it through the asynchronous data transmission connection to the device under test.
