Re: [uCsimm] 125 micro second latency - REALTIME?

From: Hartmut Mueller (hartmut@wendolene.ping.de)
Date: Tue Apr 18 2000 - 11:11:41 EDT


> However, you have to keep in Mind, that Ethernet itself it not an
> deterministic network. This means that you don't actually _know_ wheter you
> will be able to send every 125 uS. The Medium could be in use - and if there
> is a collision at the first attempt to send a packet, then you have to wait
> a _RANDOM_ time - but I don't know in which range this backoff-time lays.

This is not the complete truth. There is one approach to fulfill the
need for a deterministic Ethernet (which is called Industrial Ethernet).
They use switches to eleminate collisions, one switch port per device.
It makes sense to use the uCsimm in automatisation, fabs or HVAC to
reduce the costs for reengeneering every time a new controller chip is
involved.

Yours, Hartmut
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