[Ed in SoDak]

Is the OLD RS232 a command for the HDX modification? I don't know anything about that upgrade. Normally on a standard RS232 you have OPEN, INPUT and PRINT commands with additional details required for it to work properly. That is described in detail in the TI manuals.

I know for some cards, you must specify a proper CRU address. Sometimes it must be a specific address, maybe other times it can changed to another valid address that does not conflict with another card at the same CRU address. You may need to do an online search to find copies of the manuals for your CC cards to learn these restrictions, or perhaps someone who is familiar with them can offer better help than I am able to provide.
-Ed