×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Why is Ethernet Faster than RS485?

Why is Ethernet Faster than RS485?

Why is Ethernet Faster than RS485?

(OP)
Hi all,

I cannot understand why ethernet would be faster than RS485.  I read somewhere that RS485 is faster than RS232 because the output voltage range is smaller and so the transition between 0 and 1 is faster.  Is it the same idea with RS485 and ethernet?

RE: Why is Ethernet Faster than RS485?

RS232 and RS485 are both asyncronous serial. In other words, the receiving end has to figure out where the bits are in a serial stream. To do this, the transmitting UART will typically add a start bit and a stop bit, and is expected to be reasonably accurate on the baud rate. The receiving UART typically oversamples the input to 'find' the bits. Crude, but reliable up to a certain point.
That certain point comes when you are dealing with Megabit speeds. It becomes less practical for a UART to oversample an already fast signal.
The solution that Ethernet provides is an embedded clock. The receiving end extracts the clock signal, and then knows precisely where the bits are.
There are other techiques used to go faster, and pack more data in increasing the throughput, but embedded clocks are the  main reason Ethernet is faster the RS485.

-Bill
CE Designer Forum
www.cedesigner.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources