The Simplex4 boundary scan parallel input/output (I/O) Carrier4 creates fixtures for JTAG tests. These would be related to the low-to-midrange complexity electronic boards. It controls up to 312 independent I/Os. Carrier4 with BSPIO modules allow TTL digital connections and interfaces. This would be with different electrical levels such as RS232, RS485, LVDS and a discrete high voltage (15-28V).