Specifications

2 S7-1200/1500 Innovations
2.12 Internal reference ID for controller and HMI tags
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
24
Copyright
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Siemens AG 2014 All rights reserved
1. System constants of a controller can be found in the “PLC tags –
Default tag table” folder.
2. The system constants are in a separate tab in the “Default tag table”.
3. In this example the symbolic name “Robot_arm_left” was assigned for a DI
module.
You can also find the module under this name in the system constant tab.
In the user program “Robot_arm_left” is interconnected with the “GET_DIAG”
diagnostic block.
Note
You will find further information in the following entry:
What meaning do the system constants have for the S7-1200/1500 in STEP 7
(TIA Portal)?
http://support.automation.siemens.com/WW/view/en/78782836
2.12 Internal reference ID for controller and HMI tags
STEP 7, WinCC, Startdrive, Safety and others integrate into the joint data base of
the TIA Portal engineering framework. Changes of data are automatically accepted
in all the locations in the user program, independent from whether this happens in
a controller, a panel or a drive. Therefore no data inconsistencies can occur.
If you create a tag, the TIA Portal automatically creates a unique reference ID. The
reference ID cannot be viewed or programmed by you. This procedure is internal
referencing. When changing tags (address), the reference ID remains unchanged.
In the figure below the internal reference to the data is displayed schematically.
Figure 2-16: Internal reference ID for PLC and HMI
PLC_1
Internal HMI
reference ID
HMI Symbol
name
Access
mode
Connection
with PLC
009876 Motor_1 <symbolic
access>
PLC_1
000578 Valve_2 <symbolic
access>
PLC_1
PLC Symbol
name
Absolute
address
Internal PLC
reference ID
Motor_1 I0.0 000123
Valve_2 Q0.3 000138
HMI_1
NOTE
The ID will be invalid if …
 name is changed.
 type is changed.
 tag is deleted.