With the ACR9000 there are a total of six communication channels (or streams) available on the ACR9000 that can be simultaneously opened to send and receive data. They are as follows:
COM1: Serial RS-232 or RS-485
STREAM1: USB
STREAM2: Ethernet
STREAM3: Ethernet
STREAM4: Ethernet
STREAM5: Ethernet
Example: With the command of DIM STREAM1 (10000) issued in the SYS prompt of the terminal emulator, this will allocate 10000 bytes of memory for stream1 buffer.
When the resizing of a Stream1 buffer is complete, the controller then sets the "Re-dimensioned" flag (Bit Index 13 of parameter 4152) in the Stream Flags.
This can also be verified in the Terminal Emulator window with the SYS prompt, and issue a DIM command. This should return how much memory has been allocated to communication channels and programs.
Another way to verify this value has been dimension is through the numeric status in the FIFO Stream Parameters under Miscellaneous Parameters. The value for FIFO Free Character Space (P6978) should reflect the value you have dimension.
Note: One consideration must be taken when the stream is open, the Parameter P6978 will not update to show how much space is still available.