User Manual

Easy to communicate between devices
7.6 PROFIBUS
Easy Book
144 Manual, 03/2014, A5E02486774-AF
7.6.1
Communications services of the PROFIBUS CMs
The PROFIBUS CMs use the PROFIBUS DP-V1 protocol.
Types of communication with DP-V1
The following types of communication are available with DP-V1:
● Cyclic communication (CM 1242-5 and CM 1243-5)
Both PROFIBUS modules support cyclic communication for the transfer of process data
between DP slave and DP master.
Cyclic communication is handled by the operating system of the CPU. No software blocks
are required for this. The I/O data is read or written directly from/to the process image of
the CPU.
● Acyclic communication (CM 1243-5 only)
The DP master module also supports acyclic communication using software blocks:
– The "RALRM" instruction is available for interrupt handling.
– The "RDREC" and "WRREC" instructions are available for transferring configuration
and diagnostics data.
Functions not supported by the CM 1243-5: SYNC/FREEZE and Get_Master_Diag
Other communications services of the CM 1243-5
The CM 1243-5 DP master module supports the following additional communications
services:
● S7 communication
– PUT/GET services
The DP master functions as a client and server for queries from other S7 controllers or
PCs via PROFIBUS.
– PG/OP communication
The PG functions allow the downloading of configuration data and user programs from
a PG and the transfer of diagnostics data to a PG.
Possible communications partners for OP communication are HMI panels, SIMATIC
panel PCs with WinCC flexible or SCADA systems that support S7 communication.