Yes, I believe you can use the ELM327 to get DTCs from controllers other than "the" PCM (engine controller, as opposed to the transmission controller, etc.), if the those other modules are designed to respond to OBD requests for DTCs, which is another matter.
If an OBD DTC request is issued to 0x07df (a functional address), then any controller designed to respond *may* do so (e.g. transmission controller, etc.). The ELM327 seems to issue OBD requests (at least the initial "discovery" request) to 0x07df which is a kind of "global" functional address. But I'm not sure how it handles responses from modules other than the ECU at address 0x07e0.
Maybe if you set the CAN header as such "AT SH 7df" (which appears to be its default setting for 11-bit CAN) it will show responses from any responding controller?