Does not work over ethernet with the P50ib/10l

[tLybeck]

When attempting to use the driver with the P50 on any computer connected to the network via Ethernet, it crashes after 1-3 movements. This was tested with 2 separate computers, 2 separate switches, and a TP-Link router used as a switch. It does not crash on either reading position registers or setting the speed, so it seems to be something with the movement commands.