Can you connect multiple expansion boxes?
No.
You can connect a maximum of one. It can be either an EXPANSION-6 or an EXPANSION-14.
Module outputs can be connected to expansion boxes to expand their load
capacity though. For example: An FD-1-14 or FD-2-7 FanDrive connected
to a VDC-4 output, or a VLX-20 connected
to a VAC-1 output.