Siemens SIMATIC ET 200SP Manual page 15

Calling instructions for distributed I/O
Multiple calls are required for the instructions of the distributed I/O.
The duration of the call processing is dependent on the load, bus cycle time and
transmission rate. Timeouts may occur if these instructions are called in a loop within a
cycle.
Exceptions:
● Only one call is necessary for the RALRM instruction "Receive interrupt".
Program blocks for DPV1 (according to PNO standard)
● "Read data record from a DP slave" RDREC instruction is functionally equivalent to
SFC59 (write record)
● "Write data record to a DP slave" WRREC instruction is functionally equivalent to SFC58
(read record)
● "Read interrupt information from a DP slave" RALRM instruction call is made within an
interrupt OB
PNO: PROFIBUS user organization
1)
Communication module CM DP (6ES7545-5DA00-0AB0)
Manual, 12/2014, A5E33619758-AB
:
1)
Programming
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