Siemens SIMATIC NET S7-300 - E Linking to Other Systems with FETCH;WRITE

A-306
S7-CPs for Industrial Ethernet Configuring and Commissioning
Release 01/2007
C79000-G8976-C182-07
E Linking to Other Systems with FETCH/WRITE
The FETCH and WRITE modes supported on ISO transport connections, TCP,
and ISO-on-TCP connections can be used with any other device to access the S7
system memory areas.
To be able to use this type of access, for example for PC applications, you need to
know the PDU structure of the jobs. The required S7 or S5 header for request and
response frames are 16 bytes long and their structure is described in this chapter.