On Mon, 2012-03-19 at 16:15 -0700, Peter C. Wallace wrote:
... snip

Thanks Matt and Peter. I thought Smart Serial might be a marketing spin
for Modbus, but it sounds like a different animal altogether.

> No, its been designed to be real time from the beginning.

Something else I'll need to learn about.

> This is not to say the the firmware in the FPGA module could not be taught to 
> speak MODBUS 

Right now I'm interested in talking to VFD's and other userlandish
devices. Most newer VFD's seem to have Modbus and could make more
features available without adding more hardware or cabling. I haven't
seen much Smart Serial milling around the Hobby CNC area, but maybe
soon?

> but its really been designed as a synchronous (the comms are 
> standard 8 bit async) realtime master slave interface where we always expect 
> a 
> reply or fault info in a very short time period

I think Modbus expects a timely response too, but it seems mostly up to
the programmer on what to do with it. Maybe more like "if your are going
to respond, you better do it within 3.5 character spaces".

> It also supports discovery which I dont think is possible with MODBUS but Im 
> not sure of this

Modbus has a Report Slave ID query which should return more than just an
ID. I thought there was a broadcast query, but now that I'm looking for
it I can't seem to find it. 


-- 
Kirk Wallace
http://www.wallacecompany.com/machine_shop/
http://www.wallacecompany.com/E45/index.html
California, USA


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