Siemens SIMATIC ET 200AL, System Manual

Page: 1798 / 2255

Functions
5.8 Direct data exchange
PROFINET with STEP 7
Function Manual, 05/2021, A5E03444486-AL
233
Properties of direct data exchange
• Always isochronous
• Support of MRPD for MRP configuration
• No acyclic data exchange via PROFINET data record mechanisms
• No PROFINET alarms
• Configuration limits:
– Maximum data length for direct data exchange 3075 bytes including user data qualifier
– Maximum data length for a transfer area: 1024 bytes without user data qualifier
– Maximum number of transfer areas of sender: 128
– Maximum number of transfer areas of receiver: 512, distributed among a maximum of
64 receivable PROFINET frames and thus up to 64 sender CPUs
Diagnostics options of the receiver
Operating state change of sender:
•
When the sender goes from RUN to STOP, the receiver behaves as follows:
– The "SYNC_PI" and "SYNC_PO" instructions return an error message in parameter
RET_VAL during synchronization of the process image.
– With direct I/O access to the input transfer areas of the direct data exchange, OB 122
"I/O access error" is called, if present.
– Incoming diagnostic message "I/O data failure in hardware component"
• When the sender goes from STOP to RUN, the receiver behaves as follows:
– Call of OB 83 "Pull/plug interrupt" for input transfer areas of the direct data exchange
– Up until the call of OB 83, OB 122 is called if present.
– Outgoing diagnostic message "User data failure of hardware component"
Station failure/station recovery of the sender:
•
When the sender fails, e.g. due to a bus interruption, the receiver behaves as follows:
– Call of OB86 "Rack failure"
– The "SYNC_PI" and "SYNC_PO" instructions return an error message in parameter
RET_VAL during synchronization of the process image.
– With direct I/O access to the input transfer areas of the direct data exchange, OB 122
"I/O access error" is called, if present.
• When the sender recovers after a station failure, e.g. because the bus connection is re-
established, the receiver behaves as follows:
– Call of OB86 "Rack failure"