Reading And Writing Data - Siemens SIMATIC NET CP 343-1 ERPC Manual

● In the CPU, apart from the logical trigger, you can also see the variables that define the
The "ILS Workbench" for configuring the ERPC application and "STEP 7" for configuring the
SIMATIC station are shown among the configuration tools.
6.2.3

Reading and writing data

Types of read/write jobs
To allow the ERPC application to read or write data, the following options are available:
● Reading from the CPU
● Writing to the CPU
Sequence of read and write jobs
If it is problem free, a read/write job from the ERP application is executed in the following
steps:
1. The ERPC application initiates a cyclic read/write job.
2. The CP starts the read/write service with which the values are written to the CPU or read
3. Once the read jobs have been completed and the data of the read task is complete, the
4. If the ERP subscriber is unreachable, the data frame is stored on the CP.
If an error occurs, and error identified is returned and a diagnostic message is entered in the
diagnostic buffer of the CP.
CP 343-1 ERPC
Manual, 03/2010, C79000-G8976-C239-02
readable/writable data areas in the form of configurable ERPC symbols. No resources
are required on the CPU for read and write jobs from the application.
– Cyclic reading from the CPU
Following a read job, data is read cyclically from the CPU by the CP and sent to the
ERP subscriber.
– Spontaneous reading from the CPU
Following a single read job from the ERP application, data is read once from the CPU
by the CP and sent to the ERP subscriber.
– Spontaneous writing to the CPU
The data from the ERP subscriber is written to the CPU once a following a write job.
If data is requested from a logical trigger by the ERP subscriber, this is written to the
CPU using a write job.
For test purposes, the ERPC application on the CP can also accept a spontaneous
read/write job from the ILS Workbench.
from the CPU and sent to the CP.
Depending on the size of the data, one or more read/write jobs are sent. With a read task
for which more than one read job is necessary, the CP waits until the last read job is
completed.
ERPC application sends the requested data frame to the ERP subscriber.
6.2 ERPC services and communication
ERPC functions
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