ProSoft Technology 5204SE-MNET-PDPMV1 - Manual (Page 96)

5204SE-MNET-PDPMV1 ♦ ProLinx Gateway Reference
Modbus TCP/IP to PROFIBUS DP-V1 Pass-Through Master User Manual
Page 96 of 235
ProSoft Technology, Inc.
December 22, 2009
Variables can be stored in fixed, non-changeable memory locations within the
processor's memory. Such Variables are called located variables and may be
referenced by their variable name (symbol) or by their memory address.
However, Variables are not required to be assigned to specific, fixed memory
locations. If Variables are not assigned to specific memory addresses, they are
called unlocated variables and may be referenced only by their unique variable
names (symbols).
DDTs and Variables are then used to create Derived Function Blocks (DFBs).
These DFBs have input data, internal storage data, and output data variables
and DDTs associated with them. They use the data stored in DDTs and
Variables in process logic algorithms, which are also part of the DFBs. Unity Pro
offers several programming options to create the logic contained in the DFBs. All
logic in the DFBs created by ProSoft Configuration Builder (PCB) is in the form of
Structured Text (ST) program language sections, called Implements in Unity Pro.
The Application Communication Logic functions built into ProSoft Configuration
Builder (PCB) automatically create all the Variables, DDTs and DFBs required to
allow the processor to use its native Modbus TCP/IP communication protocol
capability and act as a PROFIBUS DP Master on a PROFIBUS network.
The following sections in this Reference chapter give brief descriptions of the
Variables, DDTs and DFBs created by PCB. Each DFB will be described and
grouped with its associated Variables and DDTs.
NOTE: Thorough understanding of all of this reference material is not required to successfully use
the gateway. This information is given for those users who wish to have a deeper understanding of
the inner workings of the system and to make it easier to troubleshoot potential communication or
programming problems.
4.2 Unity Pro Program Objects and Organizing Structures
The following sections outline basic Variables and Derived Data Types (DDTs)
that organize and centralize control of all the custom application logic created by
the Application Communication Logic functions of PCB. These variables and
structures will be the main ones used to allow the rest of the processor logic and
control application to interact with the 5204SE-MNET-PDPMV1 gateway, as well
as slaves on the PROFIBUS network. By manipulating values within these main
variables, you can perform all the actions required for effective Modbus TCP/IP
to PROFIBUS communication.
Based on the configuration options selected, PCB will export one set of files for
use with Modicon M340 Programmable Automation Controllers (PACs) and will
export a different set of files for use with Modicon Quantum PACs. There are
many similarities between these two sets of files. They have the same variable,
DDT, and Derived Function Block (DFB) names and have similar data structures.
However, Ethernet communication messages are created differently in Unity Pro
logic for the M340 and Quantum platforms. Therefore, the .XFM and .XSY
export files for M340 and Quantum configurations are mutually exclusive and not
interchangeable.