Using The S7-200 Explorer; Features Of The S7-200 - Siemens SIMATIC S7-200 System Manual

Using the S7-200 Explorer

The S7-200 Explorer is an extension to
the Windows Explorer application that
provides access to S7-200 PLCs and
allows the contents of each connected
PLC to be explored. The different blocks
that may reside in either the PLC or the
memory cartridge can be determined.
Properties are available for each block.
Since the S7-200 Explorer is an
extension to the Windows Explorer extension to the Windows Explorer
application, standard Windows
navigation and behaviors are supported.
The S7-200 Explorer is the mechanism used to read data log data stored within the memory
cartridge. Refer to Chapter 14 for more information about data logs.
The S7-200 Explorer can also be used to read or write user files to the memory cartridge. These
can be any type of files, Word documents, bitmap files, jpeg files, or STEP 7--Micro/WIN projects.

Features of the S7-200

The S7-200 provides several special features that allow you to customize how the S7-200
functions to better fit your application.
The S7-200 Allows Your Program to Immediately Read or Write the I/O
The S7-200 instruction set provides instructions that immediately read from or write to the physical
I/O. These immediate I/O instructions allow direct access to the actual input or output point, even
though the image registers are normally used as either the source or the destination for I/O
accesses.
The corresponding process-image input register location is not modified when you use an
immediate instruction to access an input point. The corresponding process-image output register
location is updated simultaneously when you use an immediate instruction to access an output
point.
Tip
The S7-200 handles reads of analog inputs as immediate data, unless you enable analog input
filtering. When you write a value to an analog output, the output is updated immediately.
It is usually advantageous to use the process-image register rather than to directly access inputs
or outputs during the execution of your program. There are three reasons for using the image
registers:
The sampling of all inputs at the start of the scan synchronizes and freezes the values of
-
the inputs for the program execution phase of the scan cycle. The outputs are updated from
the image register after the execution of the program is complete. This provides a stabilizing
effect on the system.
Your program can access the image register much more quickly than it can access I/O
-
points, allowing faster execution of the program.
I/O points are bit entities and must be accessed as bits or bytes, but you can access the
-
image register as bits, bytes, words, or double words. Thus, the image registers provide
additional flexibility.
PLC Concepts
Figure 4-18 S7-200 Explorer
Chapter 4
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