Serial data cannot be read properly

I am trying to get USB-to-serial communication from a Linux laptop (running Centos 6) to an RS422 device. The device passes about 1500 bytes of data in the form of three 512 byte packets every few seconds, but I have not been able to read this through Matlab.

I've used cutecom to verify that the data is in fact coming through. I have Matlab set up so that it does recognize the device when I run seriallist, and I am able to open it with:

s = serial('/dev/ttyUSB0','BaudRate',400000,'Timeout',5,'InputBufferSize',1024);
fopen(s);

This is code that has been confirmed to work on another computer, and the baudrate has been confirmed to be 400k. When I try using:

temp = fread(s,s.InputBufferSize,'uint8');

I get randomly sized data with seemingly random values. Does anyone have any recommendations on how I should proceed from here?