Re: USB or Ethernet for controller interface?

Gary wrote:
On Apr 12, 5:32 am, "Paul E. Bennett" <p...@xxxxxxxxxxxxxxxxxx> wrote:

Gary wrote:

Working on 32-bit microcontroller design that needs to interface to
industrial PC (mini-ITX, PC104, etc.) over short 3-meter cable. It is
an industrial application and the design will be DIN rail mounted
along side PLC's, relays, etc.

Any thoughts as to whether USB or Ethernet would be best?

Cost is a concern. Since this application's cable length requirement
is short, does this make USB the obvious winner?

Or, is Ethernet more robust in an industrial environment?

Sorry if this has been debated in the past. I did a search, but
didn't find much except for posts made in 2001. Let me know if there
are articles that address this.

Thank you!

No mention of desired speed of communication, no indication of what type of
equipment the microcontroller will be attached to (from a safety point of
view) and certainly no mention of the safety requirements in the
communications link (which you should not be entirely reliant on). You also
do not mention the type of data you expect to be handled and what latency
you could tolerate. So no hope of a really sensible answer.

There is a large number of communication possibilities from physical
connection details to protocol choices (RS232, RS485, CAN, USB, Ethernet,
etc.). A bit more detail from your side and maybe you will get an answer
more appropriate to your situation.

--
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Paul E. Bennett ....................<email:/...@xxxxxxxxxxxxxxxxxx>
Forth based HIDECS Consultancy .....<http://www.amleth.demon.co.uk/>
Mob: +44 (0)7811-639972
Tel: +44 (0)1235-811095
Going Forth Safely ..... EBA.www.electric-boat-association.org.uk..
********************************************************************- Hide quoted text -

- Show quoted text -


Thank you for the feedback. Here are more details:

100Mb/s Ethernet or USB are needed for thru-put. CAN & RS232/485 have
been ruled out. Ethernet or USB data rate is needed because the
design will be transferring large amounts of buffered data. The
buffer will be large enough to handle Ethernet or USB latency and the
PC's non-deterministic nature. The PC side will be used as the human-
interface and data storage. Not for time or safety critical control.

The design will be doing basic control stuff - reading sensors &
inputs and controlling actuators. The isolation Rene mentioned is
very good feedback.


Go for Ethernet and the TCP/IP stack. You'll have problems
on the non-transparency of USB protocols. The IP protocols
on Ethernet are pretty standard, and the sheer mass of the
TCP/IP community prevents any fast drastic changes, which
is an absolute necessity in industrial applications.

(Been there - done that).

--

Tauno Voipio
tauno voipio (at) iki fi
.

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