Re: SERIAL PORTS (was: cannot connect gto CP3 to the SKy 6)

Christopher Erickson

"Roland, are your new mounts going to stick with the old serial port
standard? I hope not."

Careful what you wish for...

Points to consider:

* For better or worse, RS-232 Serial has been the defacto-standard universal
denominator for decades and will likely continue to be so for decades to
come. With hardly an exception, very microcontroller made in the world
today has an RS-232 serial port cast right in its silicon. Whether you can
see them or not, RS-232 serial ports are EVERYWHERE. In fact all modern
"smart" refrigerators have hidden RS-232 serial ports that exist for the
service technicians armed with smart diagnostic tools. Even your car's
OBD-II or CANbus diagnostic interface has embedded RS-232-style serial
communications. Serial can be converted to just about anything (USB,
Ethernet, TCP/IP, Bluetooth, fiber-optic, Xbee wireless, etc.) USB can't be
converted to anything without an intervening pair of computers and the right
software on both ends, which usually doesn't exist. Not to mention the
expenses involved.

* RS-232 Serial can be run great distances (even thousands of kilometers)
using a great number of inexpensive media types and converters. USB can
barely make it across the average room without brain-splitting problems.

* Probably 90% of all problems with USB-Serial adapters are driver-software
related. Just about everything coming out of China has Chinese-written
drivers and these have always been incomplete and highly-problematic. In my
experience, the best and most trouble-free adapters use FTDI chips.
Prolific is a distant second place and everything else is almost complete
junk for any but the most basic of applications.

* For years, iOptron has offered GOTO mounts with USB interfaces instead of
serial interfaces and the unending grief experienced by their users related
to USB problems is infamous. In fact iOptron's most recent GOTO mounts have
gone back to serial interfaces! Good news for people with iOptron mounts
with USB interfaces is that all iOptron did was incorporate a Chinese
USB-to-Serial chip into the mount and the iOptron microcontroller has a
serial interface on it! Cutting two traces and installing a connector has
allowed users to bypass iOptron's junky serial-to-USB adapter chip and it's
horrible drivers.

* Having a serial interface on my mounts means I can easily control them
with a PC, wired/wireless smartphone or tablet computer. If it only had
USB, that usually eliminates the smartphone and tablet computer. SkyFi has
a wireless USB adapter (expensive) coming out that may work with some
USB-only iOptron mounts but they are already warning people that it is a
"work in progress."

* USB 1 is obsolete. USB 2 is officially obsolete. USB 3 is current but
USB 4 is right around the corner. Most USB 3 ports these days don't support
USB 1 peripherals. USB 4 ports are unlikely to support USB 1 or 2
peripherals. Why would I want to spend $10-20,000 for a premium mount with
an interface that will be obsolete and unsupported in about five years?

Like I said, be careful what you wish for.

Christopher Erickson
Consulting Engineer
Summit Kinetics
Waikoloa, HI 96738

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