HEMSA-T-029 industrial PCI-E multi-port serial adaptor is compatible with RS-485/422 standard. It converts PCI-E signal to balanced differential RS-485/422 signal. With built-in photoelectronic isolator and transient voltage suppression protector, RS-485/422 ports are designed to be protected. This series adopts advanced TVS (TRANSIENT VOLTAGE SUPPERSSOR). In normal situation, TVS tube is in high impedance state. When both ends of TVS tube are impacted by high power instantly, it lowers the impedance with super high speed, and soaks high current, so as to limit the voltage from both ends in a pre-determined value, and protect the circuit components from damage by high voltage impact. This protector provides lightning and ESD protection. It can offer 600W lightning surge protection for each wire, and surge voltage and transient over-voltage protection on circuit which could be caused by all reasons. The tiny inter-electrode capacitance ensures high speed transmission for RS-485/422 ports.