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Communicating with the KFC15/KFCD15 Module
5–3
Publication 17706.5.20 - June 1997
•
allows only one host processor or field device to transmit at any
one time
•
provides a less effective usage of resources than full duplex, but
is easier to implement
Half-duplex protocol can be used on a point-to-point link, but more
commonly it operates on a link with all nodes interfaced through
half-duplex modems. There can be from 0 to 63 decimal nodes
simultaneously connected to a single link.
With half duplex protocol, you can use a:
two-circuit system—the master sends and slaves receive on one
circuit, slaves send and master receives on the other
one-circuit system—master and slaves send and receive on the same
circuit
11030
PLC Computer
or
Other Hosts
Modem
Modem
Modem
Modem
RS-232C Link
Multidrop Network
Nodes
RS-232C Link
ControlNet
RS-232C Link
T
T
T
T
N
N
N
Nodes
ControlNet
T
T
T
T
N
N
N
KFC15/KFCD15
Nodes
ControlNet
T
T
T
T
N
N
N
KFC15/KFCD15
KFC15/KFCD15