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Problem with MCT drivers
Authored by: _merlin on Oct 13, '03 08:32:26PM

MCT chipsets are quite common. They are also used in the Dolphin Fast USB-RS232, and the no-name USB to serial interfaces sold at Jaycar in Australia. I have one myself, and it's been quite reliable.

There is a problem with the drivers, though. They do not support disabling of RTS-CTS handshaking. The software may think it has disabled handshaking, but the chipset will refuse to send data until the device it is attached to asserts the CTS line.

This is fine with most devices, as those that don't support handshaking often hold this line high permanently. However, it has been a problem with some embedded control systems that I have to program, and with my HP49G graphing calculator, as these devices have no physical CTS line.

I have two work-arounds for the problem. The first is to disable the OS X driver (physically unplug it, then use kextunload, plug it in again), and access it from Classic. Then enable the OS X driver when I want it in OS X again (unplug it, use kextload, plug it in again). The second is to make a cable with the RTS and CTS lines connected together to fool the thing.

I actually contacted MCT, and it seems they paid an independant developer to write the driver. They don't seem to have any intention of fixing it soon.



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