COBRA is a little unique compared to other firing systems as individual cues are connected to the module ground and are switched to connect to a shared set of positive pins. If you are designing a custom integration, this is no problem, however, the polarity may be reversed from what you are used to. In firework display scenarios since igniters are not sensitive to polarity, this type of wiring is not an issue.
The pin-outs on the 18S DB25 port are:
Pins 1-9 are cues 1-9 (ground)
Pins 14-22 are cues 10-18 (ground)
Pins 10-13 and 23-25 are shared positive
