Hi Snarf,
It's correct that you don't need the rt_io_comm, but "rt_io_comm -m" can give you a hint about if the otherio methods are correctly built and available also for the plc.
Note also that from V5.2 rack objects (like the GPIO) should not be placed directly under the $Node object, there should be a $NodeHier named "IO" in between.
/Claes