Flashaing LED pcb needs waterproofing and should be reprogrammable.

Hello,
We have a flashing LED light PCB, which is in an enclosure which is outdoors (on top of a truck). The PCB must be coated in waterproof conformal coating, to stop it shorting, and yet we must be able to re-program it......how do we do this?...because the conformal coating, once it covers the program header, it disallows electrical contact to the programmer.

sounds like you need a wireless link for reprogramming which means adding volume for the radio link. try something like this.
https://www.ladyada.net/make/xbee/arduino.html

I have a similar product that has to be reprogrammed with aircraft ID and it sits on the leading edge of one of the wings. Believe me that's a hostile environment! (think of a truck doing 200mph through a tropical jungle)

The whole unit, except for a water-tight battery box is inside a welded plastic box so I use a cheap 433MHz receiver unit on the PCB to pick up the programming data. It has a 'secret' preamble code to stop anything but the matching transmitter from changing the codes. It might be possible to use something similar in your product. The ones I use are: https://www.rfsolutions.co.uk/acatalog/info_FM_RRFQ1_433P.html and it's matching transmitter. With a tight wound helical antenna (2.5mm dia x 20mm long) at each end they have a range of about 50 metres, if you don't need long range just use a short PCB stub as the antenna.

Brian.

Use a multiple core cable as the main cable of the LED light. Then use two cores for power supply and others for programming. Due to long cable, you may need to reduce programming speed.