Owner manual

Chapter 3
Using The Smart Transmitter Toolkit
3-13
In this example, the primary variable is read continuously from two HART
field devices that are wired to separate 1770-HT1s. Communication with
multiple 1770-HT1s can occur asynchronously when calling the STT
subroutine.
PLC5 Processor
HART
Field
Device
4-20 mA Loop
1770HT1
1770HT16
Smart Transmitter Interface
RIO
HART
Field
Device
1770HT1
1770HT16
Smart Transmitter Interface
4-20 mA Loop
RIO
In the course of operation, if the field device does not respond, we reissue
HART command 0 to get the HART address. This example assumes that
each device data area is setup with the standard inputs for HART command
0 prior to the execution of this logic.
Device 1 uses N10 and F11
Device 2 uses N12 and F13
F15 contains both primary variable values
Programming Example 3:
Multiple HART Devices W ith
Multiple 1770HT1s