Hello,
This is not a known issue with our product with our Linux drivers and the IC and driver is widely used.
There is no difference in the behaviour of the 4 ports (COM1 to COM4 ) regarding USB communications.
The nature of USB communication has to be taken into account.
The communication with USB devices depends on multiple factors such as other USB devices on the bus, USB Host scheduling, USB latency, OS processing, etc.
You attached your setup. Is this all inclusive on custom hardware or are the elements separate?
Is your COM2 operating much differently from the other COM Ports? For example, is there more traffic?
What is each of the FT4232H ports connected to externally and what is the expected throughput of each?
Are you using flow control on all the FT4232H ports?
Could there be issues with the Linux board running out of CPU resources to access more than one device concurrently?
You could perform tests with our known good hardware and maybe connect that to a different Linux system to see what the results are like:
USB-COM485-PLUS4USB-COM422-PLUS4USB-COM232-PLUS4FT4232H-56 Mini-ModuleFT4232H Mini-ModuleFT-MOD-4232HUBThe FT-MOD-4232HUB might be useful as the ST60 2230-PU Wifi+ Bluetooth device can be connected to one of the ports.
Can you also test with our
D2XX Drivers (rather than VCP drivers) to see if the results are the same? See the
Linux Driver Installation Guide and
D2XX Programmer’s Guide for more information.
Maybe there are other FTDI Community users who can help you further.
Best Regards,
FTDI Community