Using an optically isolated serial device alleviates the problem caused by ground loops, floating grounds, or small surges. Sealevel offers a variety of optically isolated serial products including the following interfaces:

USB
2103 – 1-Port RS-232 DB25
2104 – 1-Port RS-422/485 DB25
2113 – 1-Port RS-232/422/485 DB9 (DIN Rail or Table Mount)
2213 – 2-Port RS-232/422/485 DB9 (DIN Rail or Table Mount)

Ethernet
4103 – 1-Port RS-232/422/485 DB9 (with Opto-isolated input and Reed relay)

PCI
7108 – 1-Port RS-232/422/485 DB25 (Low Profile and Full Height available)
7203 – 2-Port RS-232/422/485 DB9 (Full Height)

Compact PCI
7903 – 2-Port RS-232/422/485 DB9 (3U)

Interface Converters
1103 – 1-Port RS-232 to RS-422/485 DB25
1105 – 1-Port RS-232 to RS-422/485 Screw Terminals (DIN Rail Mount)

ISA
3189 – 2-Port RS-422/485 DB9