Rockwell Automation 1770, D17706.5.16 Ref Mnl DF1 Protocol Command - Manual (Page 33)

2–4 Understanding DF1 Protocol
Publication 1770Ć6.5.16 - October 1996
FullĆduplex Protocol
Use full-duplex protocol:
•
over a point-to-point link that allows two-way simultaneous
transmission
•
over a multidrop link where interface modules are able to
arbitrate transmission on the link
•
for high performance applications where it is necessary to get the
highest possible throughput from the available medium
If you connect an interface module to another Allen-Bradley
communication interface module, the modules automatically handle
the link arbitration. (For a list of modules that automatically handle
link arbitration, refer to page
4–1 .)
Full-duplex dial-up modems
Full-duplex dial-up modems can be used as long as a carrier is
detected before the carrier timeout (about 10 seconds). If a carrier is
not sensed before the timeout, the module drops DTR to trigger the
modem to hang up the phone. A carrier must be sensed at least
every 10 seconds to maintain the connection.
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