Siemens SIMATIC NET S7-1200 Operating Instructions Manual page 12

Application and properties
1.2 Communications services of the CM
• S7-300/400 with PROFIBUS CP (for example CP 342-5)
• SIMATIC PC stations with PROFIBUS CP
Types of communication with the CM 1243-5 in DP-V1
The following types of communication are available with DP-V1:
• Cyclic communication
The CM supports 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 instructions or
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
The CM also supports acyclic communication:
– The "RALRM" instruction is available for receiving interrupts of the DP slaves.
– The "RDREC" and "WRREC" instructions are available for transferring configuration,
Functions not supported by the CM 1243-5:
• SYNC / FREEZE
• Get_Master_Diag
Other communications services of the CM 1243-5
The CM 1243-5 supports the following additional communications services:
• S7 communication
– PUT/GET services
– PG/OP communication
12
diagnostics or I/O data.
The DP master functions as a client and server for queries from other S7 controllers or
PCs via PROFIBUS.
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.
Operating Instructions, 01/2023, C79000-G8976-C246-06
SIMATIC CM 1243-5