Sorry for the delayed response. They are models CS500 and RS500. APC says they don't have cables in stock but will contact me when they do. This is the same routine I went through with them several months ago.
And they refuse to reveal the pinout of these cables because if people make their own they might short a signal or whatever.
I can put a breakout box on it and see if there's any activity, but I'd probably miss some required detail like a null connection, so I'll have to wait.
Reply in group, but if emailing add another
zero, and remove the last word.