HEMSA-T-020 PCI-E to 2-port RS-232 multi-serial card is capable of converting single-ended PCI-E signals to RS-232 signals with a fast transient voltage suppressor protector, which is designed to protect RS-232 interfaces with today's advanced TVS. Under normal circumstances, the TVS tube is in a high resistance state. When the TVS tube is subjected to an instantaneous high-energy shock, it can reduce the impedance at both ends at a very high speed and absorb a large current. Therefore, the voltage across the two ends is clamped to a predetermined value, and the subsequent circuit elements are protected from damage due to transient high voltage shocks. This protector can effectively suppress lightning and ESD, provide 600W lightning surge protection for signal wires, as well as surges and transient over-voltage generated on the wires due to various causes. The extremely small inter-electrode capacitance ensures RS-232 high-speed transmission.