Techie Q: Lighting protection for 9-pin serial port?

Factual Questions
1

I have a client who operates a self-storage yard with a card-controlled electric gate, which connects to a PC in the office with a 9-pin serial cable. Over the weekend, they had lighting in the area that took out the PCI serial port board. I believe a surge was induced in the serial cable running from the outdoor gate to the indoor PC. Fortunately, the board took the brunt of the surge, and can be replaced.

Is there any way to isolate a 9-pin serial connection to prevent this damage in the future? The problem is this gate dates back to the old AT days, and I don’t think they want to upgrade the whole gate mechanism, which must work with the card recognition database software in the office.

2

They make serial port surge protectors. They also make serial port optical isolators. Google turns up tons of each. for around $30.

3

We use optical isolators in industrial plants all the time. They work fairly well, although a close enough lightning strike is going to toast pretty much anything that you can come up with. If possible, ground the shield of the RS-232 line where it comes inside the building instead of letting it ground through the serial card.

4

Incandescent or fluorescent? :wink:

5

Arc light, I’m pretty sure!