Re: Serial port connectivity issues
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There are some other variables that can play into
computer reliability when doing wired inter-device communications. This is
regardless of whether the communications involves USB, serial, Ethernet,
Firewire, Thunderbolt, PCI, SATA, EIDE or
whatever.
* 16 and 32-bit drivers installed on a 64-bit OS.
This almost always results in tears and corrupted registries. A good
registry repair and cleaner app usually helps. For some people,
scrubbing the drive and re-installing the OS was the only thing that worked 100%
of the time.
* Registry corruption caused by installing certain
non-64-bit apps. Messy problem to solve once created. A good
registry repair and cleaner app usually helps.
* ESD. Never plug a communications cable into a
device/PC and then let the other end lay on a carpet or floor in a cold/dry
environment. Just the act of walking past the loose end of the cable can
cause enough static electricity buildup to destroy interface
electronics.
* Ground loops. These aren't all that
common but when they exist, they can destroy or lock-up electronics or create
crazy noise problems for cameras.
* Legacy apps that are designed to synchronize with
certain smartphones, GPS's and PDA's. They often grab or
regularly-poll serial or USB ports, looking for a device to sync
with. That can prevent or disrupt communications with other
devices.
* Poor or
incomplete 16550 UART emulation. This is specific to USB-to-Serial
adapters. The 16550 UART (Universal Asynchronous Receiver/Transmitter) is
the standard serial interface chip found in computers with regular serial
interfaces. It is descended from the 16450 and the even-older 8250
UART chips. The 8250 UART was first used in the IBM-PC (and others), many,
many years ago. At any rate, the 16550 has a lot of communication
features and some very-specific physical attributes, like fixed-size data
buffers, hardware handshake management, parity bit management, baud-rate
range/control, etc. However most simple devices with serial interfaces
these days only need a couple of basic speeds and XON/XOFF software
handshaking. Consequently most-all of the no-name generic USB-Serial
adapters/drivers out there only support some of the basic 16550 functions.
This means they work with simple serial devices but maybe not more-sophisticated
serial devices and programs that need and expect more of the features and
functions of the 16550. Most of the 16550 emulation is done in the driver
code and not in the actual converter's electronics. This means that
SOMETIMES, a driver update can solve certain communications
problems.
* Black-market clones of popular chips and other electronic
components. This has caused a lot of problems for a lot of electronics
manufacturers. Prolific has been hit-hard by a rash of counterfeit chips
with their name stamped on top. A few years back, Panasonic and Toshiba
both had major incidents with exploding laptops caused by poor-quality LiIon
batteries that somehow managed to sneak into their supply chains. HP had a
rash of desktop computer failures caused by counterfeit capacitors and resistors
that came from a reputable electronics wholesaler. So far this has
not happened to FTDI and they have taken a number of steps to make sure that
each of their chips is certified and can be traced directly back to their
factory.
I hope this
helps.
Christopher
Erickson
Consulting Engineer Summit Kinetics Waikoloa, HI 96738 www.summitkinetics.com
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