Siemens Simatic S7-300 CPU 31xC Series User Manual

Commissioning
8.5 Commissioning PROFIBUS DP
S7-300, CPU 31xC and CPU 31x: Installation
8-28 Operating Instructions, Edition 08/2004, A5E00105492-05
Configuration and parameter assignment message frame
STEP 7 assists you during configuration and parameter assignment of the DP CPU. Should
you require a description of the configuration and parameter assignment frame, in order to
use a bus monitor for example, you can find it on the Internet at
http://www.ad.siemens.de/csinfo under article ID 1452338.
Commissioning
Commission the DP CPU as a DP slave in the PROFIBUS subnet as follows:
1. Switch on power, but hold the CPU in STOP mode.
2. First, switch on all other DP masters/slaves.
3. Now switch the CPU to RUN mode.
Start-up of DP CPU as DP slave
When the DP-CPU is switched to RUN mode, two mutually independent operating mode
transitions are executed:
• The CPU switches from STOP to RUN mode.
• The CPU starts data exchange with the DP master via the PROFIBUS DP interface.
Recognizing the Operating State of the DP master (Event Recognition)
The table below shows how the DP CPU operating as a DP slave recognizes operating state
transitions or data exchange interruptions.
Table 8-9 Event recognition by CPUs 31x-2 DP/31xC-2 DP as DP slave
Event What happens in the DP slave?
Bus failure interrupt
(short-circuit,
connector unplugged)
• Call of OB86 with the message Station failure
(coming event; diagnostic address of the DP slave, assigned to the DP
slave)
• With I/O access: call of OB 122
(I/O access error)
DP master.
RUN → STOP
• Call of OB82 with the message Module error
(coming event; diagnostic address of the DP slave, assigned to the DP
slave; Variable OB82_MDL_STOP=1)
DP master
RUN → STOP
• Call of OB82 with the message Module OK
(outgoing event; diagnostic address of the DP slave, assigned to the DP
slave; Variable OB82_MDL_STOP=0)
Tip:
When commissioning the CPU as DP slave, always program OB82 and OB86. This helps
you to recognize and evaluate the respective operating states or data exchange errors.

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)