1. Messages
  2. SERIAL PORTS

Re: SERIAL PORTS

Christopher Erickson
 

Ethernet and USB have considerably-higher program code and component
overhead than RS-232 and most all microcontrollers already have an RS-232
port cast in their silicon that literally comes for free.

The cable listed in the message below is a Cisco serial console cable and
isn't useful for anything else.

Here are a few of a number of devices that will convert serial RS-232 to
Ethernet:

http://www.netburner.com/products/serial_to_ethernet/sbl2e.html

These modules could give your mount an Ethernet interface, as well as it's
own web status and control interface:

http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/P
roductID/710/List/1/Default.aspx?SortField=UnitCost,ProductName

http://www.netburner.com/pink/

Serious programming would be required for either module, as well as on the
far end computer.

A box with multiple serial ports on one side (often up to 32) and a single
Ethernet connector upstream is commonly called a Terminal Server. We use
them quite frequently in the big observatories to connect a multitude of
specialized-task microcontrollers to a control PC on the observatory
network.

http://en.wikipedia.org/wiki/Terminal_server

I hope this helps.

Christopher Erickson
Consulting Engineer
Summit Kinetics
Waikoloa, HI 96738
www.summitkinetics.com

-----Original Message-----
From: ap-gto@... [mailto:ap-gto@...] On Behalf Of
tucstargzr
Sent: Thursday, October 18, 2012 8:18 PM
To: ap-gto@...
Subject: [ap-gto] Re: SERIAL PORTS


http://www.amazon.com/HDE-9-Pin-Serial-Ethernet-Adapter/sim/B004F72A9I/2

Disclaimer: I have not used any of these.

Tom
--- In ap-gto@..., "toristorii" <toris@...> wrote:

If AP were to introduce a GTOCP4 with an ethernet port instead of or in
addition to the serial ports, I would happily order two.

--- In ap-gto@..., Pete Su <pete.su@> wrote:

I could get behind Ethernet.

I find the fascination with RS232 in astronomy circles to be puzzling.
While there are certainly reasons that embedded industrial control
applications still use them (super simple device interfaces) this is
not what we are doing with telescope mounts. Telescope mounts (and
cameras, and all the other devices) use the serial line to send
commands to the mount controller which are then translated into lower
level signal to the motors or whatnot. The only rational reason I can
see to prefer RS232 for this above anything else is cable length, but
even that's a red herring IMHO. Ethernet cable runs can be just as
long and what "everyone" ends up doing anyway is to remote control the
mount using a second computer and TCP/IP, which doesn't even need a
wire.

So yeah, ethernet. It's almost as old as RS-232 anyway (invented in
the 70s, vs. the 60s).

Pete



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