TIA Portal Program_Alarm; Alarms from multiple sources

whimsey · Oct 3, 2022

Using TIA Portal v17, SIMATIC S7-1500 PLC.

I am trying to write an alarm that will trigger for multiple sources, and output the triggering source(s) in the text.

I have this sort of worked out - all sources that should trigger the alarm do, and as long as only a single source has triggered it, the text output is correct. The problem is when multiple sources have triggered the alarm at the same time.

Each source triggers a bit in an array, which is then gathered into a word, and the value of that word is checked against a text list and the results output.

Ideally, I would be check every bit in the word and output according to the state of that bit.

I can't just throw them into the SD_ inputs, because I have 12 possible sources, and there are only 10 inputs.

I would like to avoid a text list that contains every possible permutation, but that's the only way I'm seeing out of this.

Thanks.

drbitboy · Oct 3, 2022

what text do you want to display when there is more than one alarm active at the same time?

whimsey · Oct 3, 2022

Something like "Alarm Triggered. Source 1 Source 2" would be grand.

But I'd also be okay with each source triggering a separate instance of the alarm so I would end up with:

Alarm Triggered. Source 1
Alarm Triggered. Source 2

drbitboy · Oct 4, 2022

whimsey said:
Each source triggers a bit in an array [of bits? i.e. of bools?], which is then gathered into a word, and the value of that word is checked against a text list and the results output.

Ideally, I would be check every bit in the word and output according to the state of that bit.
...I would like to avoid a text list that contains every possible permutation, but that's the only way I'm seeing out of this.

Yes, well a list of the permutation of 12 bits has 4096 elements, so that is a non-starter, unless you generate it programmatically.

Why not use the array of bits to choose which messages to append to the alarm text?

If that array is not available, can you not look at the individual bits in the word e.g. something equivalent to this



message := "Alarm(s) triggered"

IF alarm_word.%X0 THEN message := message + "; Source 0"; END_IF;

IF alarm_word.%X1 THEN message := message + "; Source 1"; END_IF;

etc.

That assumes strings can be concatenated with the [+] operator; if that is not the case, I imagine there is some other way to concatenate strings.

You could also do this with bit-wise ANDs against the alarm_word e.g. [alarm_word AND 1], [alarm_word AND 2], [alarm_word AND 4], ..., [alarm_word AND 2048]; I am pretty sure TIA also has a bit-wise AND instruction in ladder.

whimsey said:
I can't just throw them into the SD_ inputs, because I have 12 possible sources, and there are only 10 inputs.

I don't understand this; is this saying there would be a hardware solution if the PLC had 12 (SD_?) inputs?

Lare · Oct 4, 2022

Why you try to trigger only one alarm with different texts from multiple locations.
Isn't it easier to trigger seperate alarms and showing correct txt on these different alarms if there is several alarms same time?
So you code 12 different alarmbits and show texts on these if alarm is active.

It should be also possible to change txt parts to alarm on panel side.

https://www.dmcinfo.com/latest-thinking/blog/id/9268/customizing-hmi-alarm-text-in-tia-portal

mk42 · Oct 5, 2022

whimsey said:
Using TIA Portal v17, SIMATIC S7-1500 PLC.

I am trying to write an alarm that will trigger for multiple sources, and output the triggering source(s) in the text.

Is the goal to only have one summary alarm to avoid overwhelming the operator?

drbitboy said:

I think something along these lines would be a decent approach, that only gives one tag to pass into the alarm.

drbitboy said:
I don't understand this; is this saying there would be a hardware solution if the PLC had 12 (SD_?) inputs?

The Program_Alarm instruction in the S7-1500 allows you to pass the values of up to 10 tags (linked as inputs called SD_1 - SD_10) into the text of the PLC alarm. Still though, I'm not sure that helps here, because

whimsey · Oct 7, 2022

mk42 said:
Is the goal to only have one summary alarm to avoid overwhelming the operator?

Pretty much exactly this.

The way it is right now the operator gets:

Alarm triggered! See messages for more information.
Alarm information: Source 1
Alarm information: Source 2
Alarm information: Source 3

For up to twelve sources, which can be a lot to sift through.

I will see about setting up a string for it to read from, I didn't consider that as a possibility.

TIA Portal Program_Alarm; Alarms from multiple sources

whimsey

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drbitboy

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whimsey

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Lare

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whimsey

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