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Entry type: FAQ Entry ID: 22411008, Entry date: 01/03/2006

How can you evaluate the ACK key on a touch operator panel?

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You cannot assign any fixed function to the ACK key on touch operator panels.
In order to determine whether the ACK key has been activated on a touch operator panel you must evaluate the variable for the "Alarm Ack. OP" area pointer via the controller.
Via this area pointer the operator panel informs the controller which error messages have been acknowledged on the operator panel.

If an operator acknowledges a bit message, then a specific bit is set in the variable for the "Alarm Ack. OP" area pointer. This change in the variable is evaluated by the "Exclusive OR word" operation.
Via this evaluation you can then trigger other functions such as an error alarm acknowledgment via the PLC, for example.

Fig. 01

Program description:

The ACK key is to used for acknowledging error messages via the controller. There are several touch operator panels on which the identical error message is displayed in the event of an error. It should be possible to acknowledge all error messages at once on any one of these operator panels.

Program contents:
The program contains the S7 controller program and an MP370 Touch and a TP270 Touch configuration.
If one or more messages are triggered and subsequently the ACK key on one of the operator panels is pressed, then the error messages are acknowledge at the same time on both operator panels (MP370/TP270) via the controller program.
You can change the program at will to meet your specific requirements.
Evaluation of the ACK key always follows the same pattern (evaluation of the acknowledge bit).

The sample program attached contains the evaluation of a total of 48 error messages.

Fig. 02

The attached download contains the functions described above. You can change the project to suit your requirements.

Ack_quit.exe ( 785 KB )  

Copy the file into a separate folder and then start the file with a double-click. The project is then unpacked automatically. You can then open and process the extracted project.

Runnability and test environment:
The example can be used on all the CPU types of SIMATIC S7-300 and S7-400.
The following table lists the components that have been used to create this entry and verify the functions described.

Component Product and version
PC operating system Microsoft Windows XP V5.1 SP1
Standard Tools STEP 7 V5.3 SP1
Engineering Tools -
HMI Software ProTool/Pro V6.0 SP3
HMI devices 1. MP370 Touch
2. TP270 Touch
Controllers S7 CPU 316-2DP
Table 1: Creation environment of the download attached