Downloading In Run Mode - Siemens SIMATIC S7-1200 Manual

11.15

Downloading in RUN mode

The CPU supports "Download in RUN mode". This capability is intended to allow you to
make small changes to a user program with minimal disturbance to the process being
controlled by the program. However, implementing this capability also allows massive
program changes that could be disruptive or even dangerous.
When you download changes to the CPU in RUN mode, the changes immediately affect
process operation. Changing the program in RUN mode can result in unexpected system
operation, which could cause death or serious injury to personnel, and/or damage to
equipment.
Only authorized personnel who understand the effects of RUN mode changes on system
operation should perform a download in RUN mode.
The "Download in RUN mode" feature allows you to make changes to a program and
download them to your CPU without switching to STOP mode:
● You can make minor changes to your current process without having to shut down (for
● You can debug a program more quickly with this feature (for example, invert the logic for
You can make the following program block and tag changes and download them in RUN
mode:
● Create, overwrite, and delete Functions (FC), Function Blocks (FB), and Tag tables.
● Create and delete Data Blocks (DB); however, DB structure changes cannot be
● Overwrite Organization Blocks (OB); however, you cannot create or delete OBs.
A maximum number of ten blocks can be downloaded in RUN mode at one time. If more
than ten blocks are downloaded, the CPU must be placed into STOP mode.
If you download changes to a real process (as opposed to a simulated process, which you
might do in the course of debugging a program), it is vital to think through the possible safety
consequences to machines and machine operators before you download.
Note
If the CPU is in RUN mode and program changes have been made, the TIA Portal will
always try to download in RUN first. If you do not want this to happen, you must put the CPU
into STOP.
If the changes made are not supported in "Download in RUN", the TIA Portal will prompt the
user that the CPU must go to STOP.
Easy Book
Manual, 11/2011, A5E02486774-04
WARNING
example, change a parameter value).
a normally open or normally closed switch).
overwritten. Initial DB values can be overwritten. You cannot download a web server DB
(control or fragment) in RUN mode.
Easy to use the online tools
11.15 Downloading in RUN mode
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