One of the issues with the Easytouch motherboards, is that J20 port has 17 volts on the red pin and the RS485 chip using pins green and yellow can only withstand 12v. Any shorts of power (red) to D+ (yellow) or D- (green) and the RS485 chip is killed. This is in addition to any lightning concerns...
Ogdento had suggested to me that the RS485 chip could be upgraded to a XR3085XID-F, RS485 chip which can withstand 18v. Since I see a lot of these motherboards, I have seen the RS485 chip fail and have replaced with the improved XR3085XID-F. Not fun since it is under the LCD display.
I believe a RS485 surge protector as close as possible to the motherboard is a good idea.
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