Siemens S7/TIA v18: Using a button press to Write to a DataLog...

[Mas01]

Context: PLC= S7-1212C, HMI=KTP1200 Basic.

Hi,

The operator has reported that, from time-to-time, when he presses the "Generate Report" button on the HMI (for button properties, see pic), the datalog (CSV file) is not being updated with a new row of data. Most of the times it does work, but occasionally not.

At the moment, DataLogWrite is called when "TA_DB.Report_Button_Pressed" is TRUE (Network 45, see pic).

My question is: Is there a better way than the Normally-Open contact, to trigger the REQ input of the DataLogWrite?

e.g. Is it better to use the button's rising-edge signal for REQ?

Happy to expand on any of the above.

Any suggestions most welcome.

Thanks in advance.

 

[Manglemender]

Just a thought. Your button is configured to set a bit when pressed and reset when released; the problem with this approach is that if you press teh button and then slide your finger off the button, the "Reset Bit" is omitted. You would be better off using the "on Click" event to set the request to log and then have the PLC code reset the bit when the task is done.

Nick

 

[Mas01]

Just a thought. Your button is configured to set a bit when pressed and reset when released; the problem with this approach is that if you press teh button and then slide your finger off the button, the "Reset Bit" is omitted. You would be better off using the "on Click" event to set the request to log and then have the PLC code reset the bit when the task is done.

Nick

Cheers - yes, you're right about the bit being Set when pressed & Reset when released (see pic of RELEASE properties attached).

I assumed that "on Click" was something to do with a mouse button click, so I didn't use that feature. I'll look into doing something like you suggested, thanks.

 

[JesperMP]

Agree with Manglemender.
I would set a bit by the HMI.
In the PLC, when the HMI bit is set, increment a counter, set the REQ bit high, and reset the HMI bit (*).
Reset the REQ bit upon DONE or ERROR.
Display the counter on the HMI, and include the counter in the values to be logged.

*: This causes the REQ to be set by the rising edge of the HMI bit.

 

[Manglemender]

I assumed that "on Click" was something to do with a mouse button click, so I didn't use that feature.

A Click event is a press and a release.

The other potential problem with your original approach is that the button may pressed and released so fast that the PLC is not updated and that is the other reason to set a request bit and have the PLC deal with it. @Jespers suggestion of a count is also a great addition.

Nick

 

[Mas01]

UPDATE: That worked a treat, so cheers @Manglemender & @JesperMP.