Spectrum Controls 1769sc-IF4IH User Manual page 122

8-6
Compact IO™ Isolated HART Analog Input Module
Section 8.2
MicroLogix 1500
User' s Manual 0300215-03 Rev. A
The following ladder samples provide a working HART solution for the MicroLogix
1500 when used with the IF4IH module. The following table briefly describes each
routine in the project file.
It is recommended that a 1764-LRP series C processor with firmware version
!
5 or higher be used. The LRP processor supports floating point files, which
is required to read floating point data from the IF4IH.
Attention
Table 8-1 (Routine Description)
Routine
MAIN
PACKETS
MSG_TO_MOD
SRC_CHECK
DEST_CHECKSUM
HART_MSG
WORD_BYTE
HART_CHECK
BYTE_WORD
Description
The main routine is the starting point for the ladder
program.
The "packets" routine is used to demultiplex the HART
data from the input file to individual integer files, so that
the data can be viewed or used within the ladder program.
This routine is called from the MAIN routine.
This routine is used to send and receive messages to and
from the module. Refer to Chapter 7 for more details
regarding sending and receiving messages. This routine is
called from the HART_MSG routine.
Calculates the checksum for a message sent to the module
one page at a time. This routine is called from the
MSG_TO_MOD routine.
This routine calculates the checksum for a message
received from the module one page at a time. This routine
is called from the MSG_TO_MOD routine.
This routine composes HART messages that will be sent to
the module/field transmitter. This routine is called from
the MAIN routine.
Converts word data to its byte equivalent. This routine is
called from the HART_MSG routine.
Calculates the checksum for the HART message being sent
to the module/field device. This routine is called from the
HART_MSG routine.
Converts byte data to its word equivalent. This routine is
called by the HART_MSG routine.