ProSoft Technology MVI94-MCM-MHI - Manual (Page 25)

MVI94-MCM ♦ Flex I/O Platform Configuration
Serial Communications Modbus Communication Module User Manual
ProSoft Technology, Inc. Page 25 of 109
March 29, 2011
3.5 Floating-Point Data Handling (Modbus Master)
In many applications, it is necessary to read or write floating-point data to the
device. The sample program only provides an INT array for the ReadData and
Write Data array (16-bit signed integer value). In order to read/write floating-point
data to and from the device, you must add additional ladder logic to handle the
conversion of the data to a REAL data type within the FLEX processor. This is
very easy to accomplish.
The following topics show how to read or write data to a device. These topics
also show when to use the Float Flag and Float Start parameters within the
module configuration. For all applications, floating-point data can be read from a
device without any changes to the Float Flag and Float Start parameters. You
only need to configure these parameters to issue a Write command to a device
that uses a single Modbus address, such as 47001, to represent a single floating-
point value.
The MVI94-MCM module can be used with many different processors. The
following describes using the module with a ControlLogix processor.
3.5.1 Floating-Point Data Handling (Modbus Master)
In many applications, it is necessary to read or write floating-point data to the
Slave device. The sample program only provides an INT array for the ReadData
and Write Data array (16-bit signed integer value). In order to read/write floating-
point data to and from the Slave device, you must add additional ladder to handle
the conversion of the data to a REAL data type within the ControlLogix
processor. This is very easy to accomplish.
The following topics show how to read or write data to a Slave device. These
topics also show when to use the Float Flag and Float Start parameters within
the module configuration. For all applications, floating-point data can be read
from a device without any changes to the Float Flag and Float Start parameters.
You only need to configure these parameters to issue a Write command to a
device that uses a single Modbus address, such as 47001, to represent a single
floating-point value.