Displaying Alarms

Hi all,
I am trying to come up with a standard way to handle alarms and display them in a HMI message display The HMI could be Wonderware ,Panelview, Infilink,or through Kepware OPC
Example:
Alarm 1 = Water Tank Level High B3:0/0
Alarm 2 = Oven Temperature High B3:0/1
Alarm 3 = Low oil Pressure B3:0/2

Using RSlogix500 the above alarms are handled by setting the corresponding Bit address.With this method how does the HMI display the alarm descriptions?

I have thought about replacing the bit address with a String word (ST) for each alarm then the HMI display would read the String word, but each string is 42 words and some applications have more than 50 alarms.

Another idea is to move the alarm number to an integer file then in the HMI there would be a script to decode the alarm.
Example In HMI : IF N7:0 = 1 THEN Display “WaterTank Level High” OR
IF N7:1 = 2 THEN Display “Oven Temperature High”
This would only work with HMI’s that have a scripting function.
Any other thoughts on how to display the alarm descriptions in a HMI ?

Most modern HMIs allow you to attach a text message to a discrete bit read in order to display alarms. Many likewise allow a text message to be attached to analog alarms that may be triggered internally in the HMI. It appears to me that you are seeking a solution to a problem that doesn't exist.

Thanks Bit_Bucket,
For each alarm bit would there have to be a HMI tag created?

Ray,

If you take the Panelview+ as an example - it allows you to create an array to display individual alarm messages (e.g N20:0 14 would create 14 words of alarm bits starting at N20:0/0). In the 'Alarm Setup' you then define your Alarm Trigger and each trigger BIT contains its own Message Text...

There are several examples on here of this method. If you can't track a few down, i can post screen shots.

This applies to the FTView/Panelview+ platform - other vendors have similar approaches.

Hope this helps,

Rob

Ray S said:

Thanks Bit_Bucket,
For each alarm bit would there have to be a HMI tag created?

Click to expand...

Yes. That would be the typical scenario.

There is another way for example first up alarm, most HMI's have multiple text lists based on a value in a register.
so an integer tag driving a text list would be
0 Blank (or no alarm)
1 Alarm 1
2 Alarm 2 and so on
Then you could iterate through a real alarm list (or part of if broken down into areas) so test each alarm bit in turn & increment the integer, when you arrive at a true jump over the iteration so for example if alarm bit 23 was on the count would equal 23 then skip the rest so the value stored in the integer will be 23 and this will display Alarm 23 on the HMI.
Still keep the alarms page but if you categorize the alarms in areas for example production vessel 1 then display this text list on the display for that vessel it will give the operator the first alarm that caused the problem rather than look at an alarm page that may have a number of alarms probably from some other process as well.
I have used this many times and have created standard software in a number of plc types.

Thanks for all the replys.
From Parky's reply i found using a File bit Compare (FBC)instruction works well for this method returning a position value when its finds a true alarm bit.In the HMI a multi text list displays the alarm corresponding to the position value.

Glad to help, as a matter of interest if using this method try to arrange the alarm bits in order of priority that way the highest priority alarm will be the first.
I still use an contiguous area for alarm bits but arrange them in blocks for different areas, then prioritize them in order so you still have alarms to be displayed on an alarm page but in the case where more than one alarm may be active only the highest priority alarm message is displayed on the relevant page but all alarms will show on the alarm page.