Depending on how you're communicating with the 90-30, you might be able to use Modbus. I'm assuming Modbus is the native protocol of the Magelis line, dangerous as that assumption might be. Either of the ports on a CMM311 module can be configured as Modbus slaves as can the serial ports on a CPU351 or CPU363.
Modbus can only directly access %I, %Q, %AI, and %R memory in the 90-30. If you need to display data from other types (%M for example), you'll need to add ladder logic to copy the data to one of those four types.