Reading and processing measured values
6.4 Read measured value from a measured value data record
Analog input module AI Energy Meter 480VAC ST (6ES7134-6PA20-0BD0)
42 Manual, 12/2015, A5E36061895-AA
Read measured value from a measured value data record
Introduction
To read measured values of a measured value data record, use the RDREC instruction. The
read values are stored in a PLC variable with user-defined data type (UDT).
You can find more information on this in the STEP 7 documentation, under the keyword
"RDREC".
● STEP 7 is open.
● AI Energy Meter 480VAC ST is configured.
1. In STEP 7 create a user-defined data type with the structure of the data record to be
read.
2. Insert the number of structural elements, which corresponds to the number of entries
contained in the measured value data record.
3. Insert the RDREC instruction in the user program.
4. Configure the RDREC instruction as follows:
– ID: Hardware identifier or start address of the Energy Meter (depending on the CPU
used).
– INDEX: Number of measured value data record whose entries are read.
– MLEN: Length of the measured value data record in bytes. "0" if all the entries are to
be read.
– RECORD: Target range for the read data record Length depends on MLEN.
5. Call the RDREC instruction with REQ = 1.
The values from the measured value data record were transferred into the target data area.
Basics for reading measured values (Page 35)
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