User's Manual

7ML19985LT01 SITRANS LR560 (PROFIBUS PA) – OPERATING INSTRUCTIONS Page 131
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F: Communications PA
Configuring a device
See Configuring a new device on page 40.
Configuring PROFIBUS PA with an S7-300/ 400 PLC
1) If SITRANS LR560 is not listed in the STEP 7 device catalog, you can download the
GSD file from the Siemens Web site and import it into Step 7. Go to
www.siemens.com/LR560
and click Downloads.
2) Add the SITRANS LR560 "rack": click and drag the SITRANS LR560 folder from the
hardware catalog.
3) Fill the rack with desired modules, by dragging and dropping them from the
hardware catalog.
4) After configuring PROFIBUS PA in steps 2 and 3, download it to the PLC.
5) Add code to the PLC program to read data consistently using the SFC14.
Cyclic versus Acyclic Data
When you request data from a device via PROFIBUS PA, you have two choices. Cyclic
data is provided at every bus scan: acyclic data is requested and provided as needed.
Input information is always requested at every bus scan and is set up as cyclic data.
Configuration information is only needed periodically and is set up as acyclic data.
Cyclic Data
When you configure SITRANS LR560 on the PROFIBUS PA bus, there are two slots
available for modules.
Slot 0 always transmits AIFB1 information
1)
; slot 1 defaults to Free Place, but can be
changed to AIFB2 information. If you do not wish to have data transmitted, then you must
use a Free Place module in that slot.
Each of the two Analog Input Function Blocks can be set up to return Level, or Distance.
Within the function blocks, the values are scaled according to the user requirements
(please see
AIFB (simulation, mode and status) on page 127 for details).
(continued on next page)
Note: Each of the slots has to have a module defined in it.
1)
For more information, please see AIFB (simulation, mode and status) on page
127.