Access to the safety-oriented data channel
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TR - ECE - TI - DGB - 0292 - 01
09/20/2016
6 Access to the safety-oriented data channel
The safety-oriented data channel in the module
CD_75_-EPN I/O safety_1
is
accessed via the process image, as with a standard periphery. However, direct access
is not permitted. The safety-oriented data channel of the measuring system may only
be accessed from the generated F-runtime group.
The actual communication between F-CPU (process image) and measuring system
for updating the process image takes place hidden in the background, by means of the
PROFIsafe protocol.
The measuring system occupies a larger area in the process image in the
CD_75_-
EPN I/O safety_1
module, due to the PROFIsafe protocol, than is required for the
measuring system function. The
F-Parameter Block
contained in the process
image is not included in the useful data. When accessing the process image in the
safety program, only access to the pure useful data is permitted!
6.1 Output of passivated data (substitute values) in case of error
The safety function requires that for passivation in the safety-oriented channel in the
CD_75_-EPN I/O safety_1
module, the substitute values (0) are used in the
following cases instead of the cyclically output values. This status is indicated via the
F-Periphery-DB
with
PASS_OUT
= 1, see below.
● at start-up of the F-System
● in the case of errors in the safety-oriented communication between F-CPU and
measuring system via the PROFIsafe protocol
● if the value set for the
window increments
under the
iParameters
is
exceeded and/or the internally calculated PROFIsafe telegram is defective
● if the permissible ambient temperature range specified under the corresponding
article number is not reached or is exceeded
● If the measuring system is supplied with >36 V DC for longer than 200 ms
6.2 F-Periphery-DB
For each F-Periphery and each measuring system an
F-IO data block
is
generated automatically during configuration in
TIA Portal V13
. With reference to
the generated safety program, see chapter "Safety Program Creation - Configuration
Example", this is block
F00000_CD_75_-EPNI/Osafety_1 [DB30002]
for the
measuring system. The F-IO data block contains tags which can be analyzed in the
safety program and can or must be written. An exception is the tag
DIAG
, which may
only be analyzed in the standard user program. Modification of the initial/current
values of the tags directly in the F-IO data block is not possible, as the F-IO data block
know-how-protected
.
The tags of the measuring system F-IO data block must be accessed in the following
cases:
● user acknowledgment of the measuring system after communication errors or
after the start-up phase
● during execution of the preset adjustment function
● when analyzing whether passivated or cyclical data are output
● if the cyclical data of the
CD_75_-EPN I/O safety_1
module are to be
passivated depending on defined states of the safety program, e.g. group
passivation
