v4.1 - Alarm When Exiting State

[jimg@gsp]

I am attempting to sound a "short" alarm on a state exit condition.

I have read where the short alarm is 6 seconds.

The exit condition calls another state. I have timers set in the initial state and the called state. They determine the exit condition. Both timers are set to much longer time periods than 6 seconds.

When I set the short alarm on exit, the alarm sounds continuously until I manually stop the state.

In utilization of this feature, is the alarm output (direct on/off) supposed to be to to enabled/on?

Please inform me as to where I am going wrong here.

Thanks!

[JonW]

There are two ways to do alarms. The default way is a software alarm that your computer will utilize via the speaker for the alarm sound. Depending on computer and browser, this may or may not work well.

The second way (and my preferred way) is to utilize an external alarm on one of the BCS outputs - which is what it sounds like you are doing. There are a couple of setup items that need to be done to facilitate linking your hardware alarm to the software alarm. In the "General Settings" area of the "Settings" tab, you need to check the item "Alarm To Register 10". This will assert register 10 whenever the alarm is activated. The final piece to this is to create a ladder logic trigger to control the actual output each time register 10 is asserted.

When using the hardware alarm, do not set the status of the alarm output in any of your states.

The image below shows two ladder logic rules that can be used with the alarm. The first line makes it so that when register 10 is asserted, that the BCS will turn on the output that has the alarm wired to it (in this case out15). The second line can be used if you want to have a push-button switch setup to clear the alarms.

[jimg@gsp]

Ok. My alarm output is 9.

I have set up ladder logic as shown below. The alarm in exit now functions only through the PC speaker. How do I get this alarm to sound though the hardware alarm?

Thanks, Jon.

[JonW]

You haven't completed the "circuit" in the ladder logic. You need a complete circuit from left to right for the logic to function.

You need to drop a wire "contact" on the unused boxes and drop a straight connecting "wire" in the space between the boxes. This will create a complete circuit across the line as shown in my example.

[jimg@gsp]

That worked perfectly. Thank you for your patience.

I need to learn Ladder Logic. Can you direct me to a good source?

I appreciate your time and consideration.

[JonW]

Have you read the section in the online manual?
http://docs.embeddedcc.com/ladder_logic/

[jimg@gsp]

Got it.

Thanks, Jon.

[jimg@gsp]

I now have this feature operational per your above instructions. Thanks for that.

When the Alarm When Existing State is set to Short and I set it for successive states, occasionally I get a short alarm (less than 6 seconds followed by a short delay and another short alarm.

I cannot determine what causes this, as I can run the same process without any changes at different times with varying result.

Not a huge issue, but is this avoidable?

Thanks again for your time.

[JonW]

Not clear on the issue. With the successive states, are you jumping through multiple states quickly and each has alarm on exit set?

[jimg@gsp]

I am using this in a process specifically to sound alarms at hop additions in the boil. I have (6) states that will sound an alarm at different expired times within a 90 minute boil.

To test this, I have the timer durations truncated to 20 seconds. I thought that this would be enough time after the 6 second alarm.

I will try with an increased separation for testing.