Configuration and operation
5.4 Configuring data points and messages
Configuring data points and messages
Data point-related communication with the CPU
No program blocks need to be programmed for the CP to transfer user data between the
station and communications partner. The data areas in the memory of the CPU intended for
communication with the partner are configured data point-related on the CP. Each data point
is linked to a PLC tag or a data block on the CPU.
Requirement: Created PLC tags and/or data blocks (DBs)
PLC tags or DBs must first be created in the CPU program to allow configuration of the data
The PLC tags for data point configuration can be created in the standard tag table or in a
user-defined tag table. All PLC tags intended to be used for data point configuration must
have the attribute "Visible in HMI".
Address areas of the PLC tags are input, output or bit memory areas on the CPU.
Number of PLC tags
Remember the maximum possible number of PLC tags the can be used for data point
configuration in the section Configuration limits and performance data (Page 13).
The formats and S7 data types of the PLC tags that are compatible with the protocol-specific
data point types of the CP can be found in the section Datapoint types (Page 33).
Access to the memory areas of the CPU
The values of the PLC tags or DBs referenced by the data points are read and transferred to
the communications partner by the CP.
Data received from the communications partner is written by the CP to the CPU via the PLC
tags or DBs.
Operating Instructions, 02/2015, C79000-G8976-C384-01
CP 1243-1 PCC