I recommend that you use a Redlion DA10D or DA30D Communications gateway. You can pull data from the HC900 using Modbus TCP and then pick your favorite method to talk to the A-B PLC to get the data there.
Yes, it will take some work, but Crimson 3.1 and 3.2 are so flexible, you can make it happen.
I just finished setting up a DA30D to pull points from a CompactLogiX PLC to put into a Modbus Slave block for a recorder to use (I also tested it with an HC900 for the fun of it).