USB ACM device problem

I am having problems porting a Linux C++ program to the Beaglebone Black (BBB) Debian platform (uname -r shows 3.8.13-bone47) from an old Linux Intel laptop running Debian (uname -r shows 3.16.0-4-686-pae). The program polls a custom analog to digital conversion board over a USB CDC data link, moving about 230K bytes per second. The custom board provides an interface via a PIC CDC RS-232 emulator (Microchip Technology). The C++ program uses simple Linux open(2), read(2), and write(2) for data retrieval. The custom board shows up as in dmesg as “ttyACM0: USB ACM device” on both the BBB and the old Debian laptop.

The program runs very well on the old Debian laptop. But, just a few hundred bytes trickle in before a .3 second timeout from the BBB after a very slow start. It acts as it there is an interrupt problem.

I am early in the troubleshooting process and want to see if anyone has ideas about where I should look first. I have duplicated the problem on several BBBs. I have spend some time on web searches and see similar problems with solutions, but have found nothing that helps so far.

I am new to Linux, the BBB platform, and have never posted a request for help before, so please don’t underestimate my ignorance.