Siemens SINUMERIK 840Di sl Function Manual page 147

12/2008
Description of the "Feedback to PLC" function
The function that provides feedback related to any given trigger event to the PLC
writes individual pieces of information to the PLC.
For this purpose, four bytes (DBB118, DBB119, DBB120, and DBB121) are
available in DB10 at the interface of the SINUMERIK PLC.
In the SIMATIC PLC, up to 8 bytes are available for this purpose in a freely
configurable DB at any block address. The address range must be set up in one
stretch before and after the user area, each with an extra 4 bytes in which a label is
to be stored. The label before the user addresses is 'ePS[', and the label after is
']ePS' , each in ASCII format (corresponding to a hex format of 65, 50, 53, 5B and
5D, 65, 50, 53).
If you also want to use the freely configurable data area in a SINUMERIK, the
same conditions apply as for the SIMATIC. You can select the distribution and
formatting per data byte, word, or double word.
Fig. 3-46: Feedback messages to PLC
The feedback messages can be written to the PLC once for each control monitor.
Variables are displayed for this purpose; these appear as they have been
configured for the feedback messages, and with the names they have been given
for the messages. ePS Network Services only allows variables to be written in a
configured format.
It is possible to switch directly to the settings menu from here in order to adjust and
configure the variable format.
Note
Variable format settings can only be changed if none of the control monitors are
writing to the variable in the set format. Any feedback messages being written
must be removed before the format can be changed.
The contents of the absolute variable addresses are completely overwritten with
the information specified here. Individual bits are written selectively. Individual bits
can only be written as bytes. For this purpose it is possible to determine whether a
bit is to be set to 1 or 0, or is to remain without an entry as it currently appears in
the PLC.
ePS Network Services ensures that in each case, a variable configured as an
absolute address is always written as a complete entity (i.e. not byte-by-byte or bit-
by-bit).
© Siemens AG 2008 All Rights Reserved
ePS Network Services, Function Manual (FH) - Release 12/2008
3 Setting up functions
3.4 Fault services
3-147