I don't know enough about the Mitsubishi line to be sure if we're talking about the same thing but....
My communications manual for the Quick Panel HMIs has reference to the 'Mitsubishi Melsec-A' series. I don't know if the 'A' in the Quick Panel manual refers to Mitsubishi Alpha series.
The manual states:
"The target display can communicate with a Mitsubishi processor using the AJ71C24 computer interface module in a A1CPU, A2CPU, and A3CPU. The AJ71C24 CIM can be used with the following base units: A32B, A35B, A38B, A55B, A58B, A65B, A68B."