Communication With The Cpu - Siemens S7-1200 Operating Instructions Manual

Configuration and operation
4.15 STEP 7 configuration of individual parameters
4.15.5

Communication with the CPU

The parameter group is displayed as soon as telecontrol communication is enabled.
Communication with the CPU
● Frame memory size
Here, you set the size of the send buffer for events.
A maximum of 64000 events divided up equally among the communications partners can
be buffered.
You will find a description of the send buffer and the functions involved in the section
Process image, type of transmission, event classes, triggers (Page 51).
CP diagnostics
In the parameter group "CP diagnostics", you have the option of reading out advanced
diagnostics data from the CP using PLC tags.
● Diagnostics trigger tag
If you want to use advanced CP diagnostics, you need to configure the "Diagnostics
trigger tag".
If the user program of the CPU sets the PLC tag "Diagnostics trigger tag" (BOOL) to 1,
the CP updates the values of the configured PLC tags for advanced diagnostics. After
writing the current values to the PLC tags for advanced diagnostics, the CP sets the
"Diagnostics trigger tag" to 0 signaling the CPU that the updated values can be read from
the PLC tags.
Reading out the following diagnostics data can be enabled selectively:
● Send buffer overflow
PLC tag (data type byte) for the send buffer overflow pre-warning. Bit 0 is set to 1 when
80% of the fill level of the send buffer is reached.
● Send buffer level
PLC tag (data type DWord) for the occupation of the send buffer. The number of saved
frames is displayed.
● Current IP address
PLC tag (data type String) for the current IP address of the CP.
● Mobile wireless signal quality (LED)
PLC tag (data type UInt) for the signal quality of the local mobile wireless network as this
is displayed by the "SIGNAL QUALITY" LED.
● Mobile wireless signal quality (dBm)
PLC tag (data type INT) for the signal quality of the local mobile wireless network as a
dBm value.
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Operating Instructions, 01/2015, C79000-G8976-C381-01
CP 1243-7 LTE