Rockwell Automation 1770-HT8 SMART TRANSMITTER - Manual (Page 100)

Chapter 4
C Communicating with the Smart
Transmitter Interface
4-35
Full Duplex
Full duplex protocol:
is a direct link that allows simultaneous two-way transmission
requires a system programmer to use interrupts and multi-tasking
techniques
is intended for high performance applications where maximum data
throughput is necessary
gives faster data throughput than half duplex, but is more difficult to
implement
Figure 4.11
Full Duplex Network
90036
Programmable
Controller or
Host Computer
Smart Transmitter Interface
Hart Field Devices
RSĆ232C Link
Half Duplex
Half duplex protocol:
is a protocol for one host processor and one or more field devices. (You
must use modems if there is more than one Smart Transmitter Interface).
allows only one host processor or field device to transmit at any one
time
provides a less effective utilization of resources than full duplex, but is
easier to implement