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User Guide
Chapter 4
GFK-3019G
Oct 2019
Modbus RTU Machine Adapter
18
—
bitBaseAddress
is an optional parameter whose value is either “0“ (the
default) or “1”. This controls the whether the Machine Adapter uses zero or
one-based addressing for bit offsets within a register.
—
defaultModbusByteOrder is an optional parameter whose value is either
“true” (the default) or “false”. This controls whether the byte order is
interpreted as the default Modbus byte ordering (big endian) or the Intel
byte ordering (little endian).
—
first16BitLow is an optional parameter whose value is either “true” (the
de
fault) or “false”. This controls whether the Machine Adapter interprets
the first 16 bits of a 32-bit data type to be the low or high word of the 32-bit
value.
—
first32BitLow is an optional parameter whose value is either “true” (the
default) or “false”. Th
is controls whether the Machine Adapter interprets
the first 32 bits of a 64-bit data type to be the low or high double word of
the 64-bit value.
—
mostSigBit is an optional parameter whose value is either “true” or “false”
(the default). This controls whether the Machine Adapter should use
Modicon bit ordering which reverses the bit order.
•
Each unit element corresponds to one Modbus RTU Slave device.
—
The id attribute must be set to the Modbus Slave Device ID.
—
Each register element corresponds to one Modbus register.
▪
The name attribute must be set to the tag name that is desired to be
associated with the given Modbus register. This is the name that will
appear in the Predix Time Series Database, for example. It must have
a unique name relative to other tags in the same Predix Time Series
Database.
▪
The dataType attribute must be set to the data type of the Modbus
register. Possible values include “BOOLEAN”, “BYTE”, “SHORT” (2
-
byte integer), “INTEGER” (4
-
byte integer), “LONG” (8
-byte integer),
“FLOAT” (4
-
byte real), “DOUBLE” (8
-
byte real), and “STRING”.
▪
The address attribute must be set to the reference address of the
Modbus register in the Modbus Slave.
▪
The registerType attribute must be set to the Modbus register type.
Possible values include “HOLDING”, “INPUT”, “DISCRETE”, and
“COIL”.
▪
The description attribute is optional and can be set to any text
description that gives a human-
readable summary of the register’s
purpose.
▪
The count attribute is only valid for STRING data types, and indicates
the number of registers used to hold the string.