Appendix H: Communication via
PROFIBUS PA
SITRANS LR 460 is a Class B, Profile Version 3.01, PA device. It supports Class 1 Master for cyclic and acyclic data exchange, and Class 2 for acyclic services. The full range of SITRANS LR 460 functions is available only over a PROFIBUS PA network.
PROFIBUS PA is an open industrial protocol. Full details about PROFIBUS PA can be obtained from PROFIBUS International at www.profibus.com.
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 LR 460 on the PROFIBUS PA bus, there are two slots available for modules.
Note: Each of the slots has to have a module defined in it.
Slot 0 always transmits AIFB1 information1; 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 (see Analog Input Function Blocks 1 and 2 on page 102 for details).
1.See Analog Input Function Blocks 1 and 2 on page 102 for more information.
7ML19985JM01 SITRANS LR 460 (PROFIBUS PA) – INSTRUCTION MANUAL | Page |
