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7
PROFIBUS DPV1
7.1
Physical interface
An
eNod4
device compatible version can be connected to a Profibus DPV1 network thanks to the SUBD 9-pin female
connector.
eNod4
supports baud rates between 9600 kbps and 12 Mbps with automatic detection.
For a complete description of the recommendations about
eNod4
Profibus DPV1 connection, please refer to
“
Characteristics and functioning
” documentation.
7.2
GSD file
eNod4
capabilities for Profibus communication are described in the corresponding GSD file (that can be easily read as
an ASCII
text file). Here are the main information’s contained in this file:
7.3
Cyclic exchanges
7.3.1
Cyclic inputs modules
eNod4
GSD file defines several modules that can be integrated to the Profibus DP cyclic frames. All types of
measurements processed by
eNod4
can be selected (net/gross/factory calibrated measurement). Moreover it is
possible to add the data that contain information about the measurement or the device status.
7.3.2
Cyclic inputs/outputs modules
eNod4
cyclic outputs might be used in combination with cyclic inputs so as to request specific commands to
eNod4
(like tare, calibration...) or to modify the values of some settings (for example, set point values). A simple protocol
described below allows writing or reading data by writing commands into
eNod4
cyclic outputs.
-
The module “
Reg. Command/Response
” uses the eNod4 functional command mechanism defined in
another chapter. The only difference concerns the “reset” and “restore default parameters” commands
which cannot be sent via cyclic exchanges immediately after an eNod4 reboot. To use them with this
cyclic exchange module, another command should be used before (cancel tare for example).
The
‘command/response register’
described by
eNod4
GSD
file is constituted by 2 IN/OUT bytes and is
working almost the same way. Its functioning will be detailed later in this document.
-
The
‘read/write request register’
described by
eNod4
GSD file is constituted by 6 IN/OUT bytes :
IN
OUT
Transaction status (2 bytes)
Transaction request (2 bytes)
Data read/written (4 bytes)
Data to be written (4 bytes)
the Profibus DP master can transmit a read or write request to
eNod4
by writing a specific code (see
the codes listed in the appendix) into the transaction request register.
for a write request, the 4 following OUT bytes can be used so as to enter the new value of the
accessed setting
eNod4
IN are then updated :
-
Transaction status is set to 0xFFFF in case of an error otherwise it takes the same value as the
one entered in the transaction request word.
-
For a read transaction, the value of the requested setting is copied into the four IN following
bytes.
-
For a write transaction the value of the data to be written is copied into the four IN following
bytes.
