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USB to RS232 adapter

IMPORTANT: the FTDI type USB to RS232 adapter is recommended INSTEAD OF THIS ! - mostly because it has more stable windows driver. This item is only kept for those who are good at downloading and installing OS drivers (trying other driver versions if necessary, disabling driver signing, whatever it takes: recommended to get 4 or more of the same type working/tested at the same batch to have clear view of their operation - the FTDI has well <1% chance of early HW problem, these types reach 1%).
>0.6m or longer cable (depending on version) that provides an RS232 port (standard, appr. -/+ 7V voltage levels, compatible with genboard v3.x) on computers with USB port (most notebooks nowadays lack builtin RS232 port).
Depending on supply shipment, one of 3 types is in inventory:

  • prolific pl2303 : the blue stlab
  • prolific pl2303 : other type eg. "best-connectivity" (overmoulded grey, and comes with a DSUB9-25 adapter, also pl2303)
  • or ch340/341 chip nice-blue semi-transparent with transparent grey cable (ch340 type only recommended for windows, might not be fully compatible with linux modprobe ch341 even with 1 line removed from ch341.c).

Driver available for all windows. But the driver from the CD (might be included if >6 pieces purchased in same order) might not be the best breed (eg. might cause mysterious communication problem apparently working with some apps under some circumstances and not with others, due to buffering problems in the windows driver: in that case another driver is needed, your windows milage may vary).
If more than one driver can be found, it's the installer's task to identify, download, install, reboot, test, ... (windows tamagochi). Some drivers may be downloadable from Unfortunately prolific has flooded the market with bad windows drivers. Prolific drivers sometimes fail even with just Brayterm, but more likely to fail with more traffic.
Sometimes even takes the whole windows with it with blue death (a driver should never, do that ! If that happens, under any circumstances, that driver is crap. After 2012 this became rare though) Even worst with lotsof traffic (as in VemsTune) especially in a noisy environment (where the adapter chip sometimes resets). We are working on workarounds to get best possible effect out of the crappy driver.
Options are
  • pl2303: using linux live-USB (which goes around the windows-prolific crap altogether). Likely the only proper solution given that the windows driver sometimes even crashes before the application could open the port (the only cure for that is a good driver or a good OS).
  • trying patterns that tend to avoid triggering the driver bugs (eg. if the flow of bytes is continuous, the windows driver dies less frequently than if the flow sometimes stops, than starts again - which is otherwise a perfectly normal flow-pattern for any serial port)
  • getting Prolific release a nonfreezing driver for contemporary windows XP, 7, etc... versions working with their sold 10+ million pl2303 chips. This seems hard. When we requested, we did not even get a reply from them. The situation got worse around 2005-2006 and after that sometimes got better (almost seemed OK at a point), sometimes worse. You need luck and patience (likely 2nd or 3d driver) to find a driver that works for your XP (or newer windows).

Pl2303 works very well on linux operating systems (driver included in kernel or modprobe pl2303) - since PL2303 is the most common USB-serial chip, most likely other OS-es too.

For the curious, the cable is powered from the host's USB port and contains

  • USB chip: Prolific PL2303 this is a powerful chip that's HW-wise outperforms most of it's competitors (eg. in max bitrate). The ch340 can usually operate up to 460800 baud (the 19200-115200 baud should not be a problem for the cable lengths used in cars, if the cable+shield is otherwise good.).
  • max232 for voltage conversion
  • more info about the broken prolific windows-XP drivers here

For more information, please visit this products webpage.
This product was added to our catalog on Monday 08 November, 2004.
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