PLC operation control
 | Available from TwinCAT 3.1 Build 4026 |
| It is your responsibility to ensure that runtime system services are activated in safe application states and deactivated only in critical ones. |
A plant or project can enter a sensitive state at runtime, where disruptive actions can endanger the entire machine or plant. However, in this state you can suppress certain commands and prevent dangerous actions. The global data type PlcAppSystemInfo is available for this purpose.
Examples of TwinCAT commands whose execution can be suppressed:
- Write values, force values
- Set a breakpoint
- Download, Online Change
If a runtime system service is requested at runtime of the project, but it is currently deactivated, you will receive a message about this in TwinCAT.
Using PlcAppSystemInfo for operation control
You can activated or deactivated operations using the _AppInfo.Flags variable of DWORD type. _AppInfo is an instance of the PlcAppSystemInfo type.
Operation | Bit of _AppInfo.Flags | Sample access |
|---|---|---|
Deactivate Write values | Bit 0 | _AppInfo.Flags.0 := TRUE; |
Deactivate Force values | Bit 1 | _AppInfo.Flags.1 := TRUE; |
Deactivate Set a breakpoint | Bit 2 | _AppInfo.Flags.2 := TRUE; |
Deactivate Download | Bit 3 | _AppInfo.Flags.3 := TRUE; |
Deactivate Online Change | Bit 4 | _AppInfo.Flags.4 := TRUE; |
See also: