Spectrum Controls 1769sc-HART Modules - Manual (Page 116)

Compact IO™ Isolated HART Analog Output Module
User’s Manual 0300217-03 Rev. A
8-6
Section 8.2
MicroLogix 1500
The following ladder samples provide a working HART solution for the MicroLogix
1500 when used with the OF4IH 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 OF4IH.
Table 8-1 (Routine Description)
Routine Description
MAIN
The main routine is the starting point for the ladder
program.
PACKETS
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.
MSG_TO_MOD
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.
SRC_CHECK
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.
DEST_CHECKSUM
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.
HART_MSG
This routine composes HART messages that will be sent to
the module/field transmitter. This routine is called from
the MAIN routine.
WORD_BYTE
Converts word data to its byte equivalent. This routine is
called from the HART_MSG routine.
HART_CHECK
Calculates the checksum for the HART message being sent
to the module/field device. This routine is called from the
HART_MSG routine.
BYTE_WORD
Converts byte data to its word equivalent. This routine is
called by the HART_MSG routine.
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Attention