Alarm Horn Manual Silence, Auto Reset.

Nova5

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May 2013
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Looking to silence an alarm from a HMI Button. Right now the HMI button command is set to Pulse the binary bit.

Will the attached logic work to silence the alarm but allow the light to remain on?

When the program starts no alarms should be present (supposing the system is properly primed) Temps will be in range, HH's will not be in alarm state. As the Start permissives require that to be correct.

Any Alarm going High in logic will set the Alarm Light+Horn to True.

So the Alarm Light Output should be TRUE on the NC switch(due to false in the referenced input), ONS sees the False/True transition, allowing the rung to go true, Latching Alarm Horn Silence Logic Bit. which will allow alarms to trigger the horn.

Next when/if the Alarm Horn Silence HMI button is pressed that run goes true and unlatchs the Alarm Horn Silence Logic Bit, silencing the alarm.

The button on the HMI is only visible and usable when an alarm has triggered the Alarm Light/Horn.

When the alarm(s) clear, the light goes false and the corresponding NC contact on line 2 goes true, latching the horn logic bit for the next alarm to successfully call for the horn.

I'm a little new at this so my explanation may be a little rough. The attachment is just from a clean program So i could look at it without affecting my actual program.

Alarms.jpg
 
do you need to use latching relays?
I am assuming you are a student - sorry if I am wrong
write a truth table for the actual control.
Normally we would reffer to this as a 'MUTE' cct
so
1. b3:0/2 is off ONS - B3:0/5 latches on
2. toggle ON b3:0/1 'ON'
3. b3:0/2 turns on
4. b3:0/5 is on b3:0/3 turns on
5. b3:0/4 is toggled ON - b3:0/5 turns off
6. system now waits for a status change
what is b3:0/1 and b3:0/4
 
try this:

XIC B3:0/1 BST OTE B3:0/2 NXB XIO B3:0/5 OTE B3:0/3 BND
BST XIC B3:0/4 NXB XIC B3:0/5 BND XIC B3:0/2 OTE B3:0/5
 
not sure if this is what you're looking for – but there are some ideas for basic alarms in the attached file ... it was written for an SLC-500 platform – but should be easily modified for anything else ...

basic ideas:

each field signal gets three separate timers ...

(1) you get to tweak the first timer to determine how long each signal can be "out of tolerance" before you consider the field input signal to be in an "alarm state" ...

(2) you get to tweak the second timer to determine how long each signal must be back "within tolerance" before you consider the "alarm state" to be cleared ...

(3) you get to tweak the third timer to determine how long an alarm state may be silenced before the horn turns back on again to remind (nag) the operator that an "alarm state" still exists ...

so ...

whenever a "new" alarm state is declared, a horn sounds – and a beacon lights up – to alert the operator that an alarm condition exists ...

the operator can press the "silence" button in order to concentrate on correcting the condition – so the horn turns off – but the beacon stays on ...

if the condition doesn't get corrected in a timely manner, the horn sounds again to remind the operator that something still needs to be done ...

naturally some field conditions require very prompt attention ... others can go quite awhile before things get serious ... and some operators might just press the silence button repeatedly and go right back to sleep ... the basic ideas in this program give a lot of flexibility in how different types of "alarms" are handled ...

.
 
try this:

XIC B3:0/1 BST OTE B3:0/2 NXB XIO B3:0/5 OTE B3:0/3 BND
BST XIC B3:0/4 NXB XIC B3:0/5 BND XIC B3:0/2 OTE B3:0/5

That should work just fine. simple change to my logic that I should have spotted, latched plenty of outputs that way in the program.. ahh mental vaporlock...
 
Last edited:
not sure if this is what you're looking for – but there are some ideas for basic alarms in the attached file ... it was written for an SLC-500 platform – but should be easily modified for anything else ...

basic ideas:

each field signal gets three separate timers ...

(1) you get to tweak the first timer to determine how long each signal can be "out of tolerance" before you consider the field input signal to be in an "alarm state" ...

(2) you get to tweak the second timer to determine how long each signal must be back "within tolerance" before you consider the "alarm state" to be cleared ...

(3) you get to tweak the third timer to determine how long an alarm state may be silenced before the horn turns back on again to remind (nag) the operator that an "alarm state" still exists ...

so ...

whenever a "new" alarm state is declared, a horn sounds – and a beacon lights up – to alert the operator that an alarm condition exists ...

the operator can press the "silence" button in order to concentrate on correcting the condition – so the horn turns off – but the beacon stays on ...

if the condition doesn't get corrected in a timely manner, the horn sounds again to remind the operator that something still needs to be done ...

naturally some field conditions require very prompt attention ... others can go quite awhile before things get serious ... and some operators might just press the silence button repeatedly and go right back to sleep ... the basic ideas in this program give a lot of flexibility in how different types of "alarms" are handled ...

.

Immediate attention alarms bring the system to a halt and alarm for attention. Others just alarm for attention.
 
Immediate attention alarms bring the system to a halt and alarm for attention. Others just alarm for attention.

certainly - and once the basic "alarm" bits are latched on, you could then do whatever is necessary to stop the system – or just to call for attention – or to do anything else required ...

the part that most people miss when setting up alarms is that SOME conditions need immediate attention – but other conditions can easily "wait awhile" before considering the situation to be an "alarm" in the first place ...

many alarm programs just lump every type of condition into one basket – with no easy way to accommodate various degrees of seriousness ... having the separate timers allows a lot of flexibility that some other alarm programs don't offer ...

it's just a suggestion ... if your system doesn't require this degree of control then feel free to ignore the suggestion ...
 
Small process skid. Doesn't need any complex alarming methodology. My statement was more how I have it configured vs anything else.


HMI will display active alarms.
 

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