Sound for critical alarms

Andreas_Wallevik · December 16, 2024, 1:00pm

Hello,

Quick question in regards to the Audio component in Perspective.

I wish to have a sound play when a critical alarm is triggered.

What would be the best way to achieve this?

Anyone have any experience with this?

pturmel · December 16, 2024, 1:05pm

You cannot rely on the browser your Perspective client is using to allow auto-play of your sound, nor be sure the sound on that PC is even on. You cannot even rely on there being an open Perspective client to play the sound.

Critical audible alerts must be wired to the system, not to any client. Preferably directly to the system's PLC, but possibly to the Ignition gateway (where a gateway event can use system.util.playSoundClip() to play through the gateway's sound card).

jlandwerlen · December 16, 2024, 2:22pm

If Ignition handles defining alarm priority, what is considered best practice for the alerts to be wired to a PLC? I've always wanted to ask others what they do on this. I know I could hard code in the PLC, but then that opens up discrepancies between what the HMI shows as an alarm priority and the PLC.

I usually setup an alarm listener and then send this data to the PLC by a gateway event. The alarm listener opens up the possibility to handle different priorities or even other alarm properties.

pturmel · December 16, 2024, 2:56pm

If a PLC is going to sound or flash the alarm (literally), I don't make the logic rely on the gateway. That's the point of having the PLC do it.

jlandwerlen · December 16, 2024, 3:04pm

Right, so how do you correlate the two (HMI <--> PLC)? We usually wire horns/lights to the PLC simply because that's easier to do, not because it's a "critical" function. Just curious on what others do on this, not meaning to hijack a thread or get in a needless debate.

pturmel · December 16, 2024, 3:08pm

When there is an HMI independent of Ignition (I prefer Vision on machines...), I don't see how the priority coordination can be anything other than custom.

When Ignition is also the HMI, I prefer that the PLC simply generate the alarms, with Ignition following the PLC's lead for critical alarms, and Ignition setting the priority for anything else. And Ignition handling all acknowledgements, if any.

jlandwerlen · December 16, 2024, 3:09pm

Ok, custom is all I could think of as well.

Andreas_Wallevik · December 17, 2024, 10:38am

Thanks for the feedback!

Here's how i solved it.

Views/AlarmView

Created an Audio Component
Created a Custom Property on the View

Name: playAlarm
Type: Boolean (automatically set to False upon creation).

Expression Binding on playAlarm
I set up an Expression Binding using runScript() to check for active alarms:

runScript("len(system.alarm.queryStatus(priority=['Critical'], state=['ActiveUnacked'])) > 0", 2500)

This checks every 2.5 seconds if there are any alarms with the following criteria:
- Priority: Critical
- State: ActiveUnacked (Active and Unacknowledged).
The result (True/False) updates the playAlarm property.

Binding playAlarm to Audio Component's props.play

I linked the play property of the Audio Component directly to the playAlarm property.

Audio Component's props.source

Added a test sound with the URL:

https://www2.cs.uic.edu/~i101/SoundFiles/taunt.wav

Test Tag

Created a test tag with a Critical setpoint to verify the alarm functionality.

Behavior

This configuration will allow the alarm sound to play only on this specific view (Views/AlarmView).

Global Playback Configuration

To enable sound playback globally, on any view or through a main view, i:

Used Session Properties for the playAlarm value.
Placed the Audio Component on a persistent view, /headerview in this case.

Testing

I tested the alarm by setting the value of the test tag to 100 (Critical setpoint), and the sound triggered successfully in the client.

michael.flagler · December 17, 2024, 2:51pm

You really should not be running that expression binding on a view like that. You're going to cause yourself a lot of headaches if/when you have lots of clients connected all running that query every 2.5 seconds.

Instead, run a timer script on the gateway that runs your script and just writes the either the count of alarms or a boolean value to a tag. Then you can use your binding off of that tag instead of a runScript expression. This guarantees it to be up to date and only running once every 2.5 seconds no matter how many clients you have.

Andreas_Wallevik · December 17, 2024, 3:16pm

Thank you so much, man.

I'm going to revise this and update the solution accordingly.

Andreas_Wallevik · December 18, 2024, 3:13pm

Current solution:

Any feedback is greatly appreciated

This still doesn't solve all problems, specifically in regards to issues pturmel mentioned. But hopefully this is somewhat more efficient.

Gateway timer script

I created a gateway timer script to monitor active critical alarms and update a memory tag named CriticalAlarmCount.

results = system.alarm.queryStatus(priority=["Critical"], state=["ActiveUnacked"])
critical_alarms = len(results)
system.tag.writeBlocking(["[TagProvider]TagFolder/CriticalAlarmCount"], [critical_alarms])

Session property

I added a custom session property named playAlarm with this expression binding:

try({[TagProvider]TagFolder/CriticalAlarmCount} > 0, false)

..triggering True when any critical alarm is active.

View Property change script

On the View where the Audio Component is located, I created a property change script for playAlarm.

def valueChanged(self, previousValue, currentValue, origin, missedEvents):
    if currentValue.value == True:
        self.getChild("root").getChild("Audio").props.play = True

...sets Audio.props.play to True when playAlarm becomes True.

Audio component

Source: URL of the audio file.
Play: Controlled via the playAlarm logic.

If i were to use the gateway and system.util.playSoundClip for this - does anyone have any resources or tips for how to set that up?

Andreas_Wallevik · December 19, 2024, 10:05am

Using system.util.playSoundClip("/sound/alarm.wav", 1.0, False) to trigger sound from GW (file is mounted to docker volume)

Getting an error that the file format is not supported by javax.sound.sampled API requirments

As far as i can see from the error, the requirements are these:

Sample rate: 22050 Hz
Bit depth: 16-bit
Channels: Mono
Encoding: PCM_SIGNED

Error message:

Caused by: org.python.core.PyException: java.lang.IllegalArgumentException: java.lang.IllegalArgumentException: No line matching interface Clip supporting format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian, and buffers of 128020 to 128020 bytes is supported.

... 26 common frames omitted

Caused by: java.lang.IllegalArgumentException: No line matching interface Clip supporting format PCM_SIGNED 44100.0 Hz, 16 bit, mono, 2 bytes/frame, little-endian, and buffers of 128020 to 128020 bytes is supported.

at java.desktop/javax.sound.sampled.AudioSystem.getLine(Unknown Source)

at com.inductiveautomation.ignition.common.script.builtin.SystemUtilities.playSoundClip(SystemUtilities.java:288)

I'm using a wav file with a bitrate of 705 kbps, which is a uncompressed 16-bit PCM WAV file

From what i can see, this audio file should work. Anyone have any thoughts?

michael.flagler · December 19, 2024, 12:25pm

Your sampling rate is too high if those requirements are strict.

pturmel · December 19, 2024, 1:06pm

I would not expect a docker container to emulate sound hardware, and if it did, where would the sound go?

Gateway sound generation presumes gateway hardware with a sound card.

Andreas_Wallevik · December 19, 2024, 1:43pm

Okay. It seems you're right. I am still new to this and was not aware of this. But thanks for pointing that out.

pturmel · December 19, 2024, 1:47pm

Consider using a VM instead of docker. Many hypervisors do provide sound card emulation that routes to the hypervisor's hardware.