<4. Explanation of Basic Item>
4-1
IM 12A01A02-72E
3rd Edition : Oct. 01, 2015-00
4.
Explanation of Basic Item
4.1
Reading cyclic parameters
In general, slave devices exchange data cyclically with the master (class 1, e.g. PLC). The
FLXA21 (slave) gets the data from the sensor, makes some calculations and makes the outcome
available through analog input blocks. The controller device (Master) requests for these process
values, makes some calculation (PID, ratio) and sends the result to an actuator. The FLXA21
contains three analog input blocks and therefore three Process values for cyclic data transfer.
The master class 1 device gets the information (of the FLXA21) by consulting the GSD file. A
device specific GSD file should be available for each device and should have an unique identifier.
All information necessary for cyclic data transfer is described in the GSD file. Refer to the manual
of the Master Class 1 device for these folders. With these files, the Master Class 1 devices are
able to start cyclic data transfer.
4.2
Integration of GSD file and IDENT Number
The GSD file and IDENT Number are necessary for PROFIBUS PA communication. Before
starting communication, the device must be specified by the GSD file in the host system and the
IDENT Number of the device.
The PROFIBUS PA device has a profile IDENT Number and a device-specific IDENT Number.
There are GSD files which correspond to each number. The profile GSD file is a general-purpose
file which is defined by the kind and number of function blocks of the device. This file helps
improve the compatibility among devices.
By setting the PROFIBUS PA IDENT Number (IDENT_NUMBER_SELECTOR) parameter of the
physical block, the IDENT Number will be linked with the corresponding GSD file.
Table 4.1 Device specific ID GSD file
Model Name
Device specific IDENT Number Device specific GSD file
FLXA21-PH
0x45D0
YEC45D0.gsd
FLXA21-SC
0x45D1
YEC45D1.gsd
Table 4.2 Profile ID GSD file
Profile ID
Profile IDENT Number
Profile GSD file
Analyzer
0x9750
pa139750.gsd
Beforehand one must configure which information will be exchanged.
There are two kinds of configurations possible. The Identifier byte (or short identifier) and the
Extended Identifier Format (or long identifier). The FLXA21 supports both kinds of configurations.
The user can choose either “Analog Input (short)” or “Analog Input (long)” and will end up with the
same result.
The function blocks of the FLXA21 are in a specific order. The configuration of the cyclic data
should be done in the same order.
For the FLXA21. The process values are mapped as follows on default.
FLXA21-PH
FLXA21-SC
slot (1)
“AI1”
pH
Conductivity
slot (2)
“AI2”
Temperature
Temperature
slot (3)
“AI3”
Empty
Empty