alarm handshake bit

to all you hmi programming guru's i have a question. What is the purpose of the alarm handshake bit. I'm setting up some HMI alarms in Factorytalk studio SE and I was wondering exactly what it was and if I needed to have it. I've seen it in logic before but unsure of what it was for.

I see a lot of views but no replies...haha.

Hello,

Well it got me curious and I just did a web search and located several places that answered the question.

How the Handshake connection works

The Handshake connection is useful for triggers that use the Value data type. Program the data source to queue alarm notifications when multiple alarms are generated for the same trigger. Use the Handshake connection to notify the data source that RSView has detected the alarm notification. Then the data source can send the next alarm to RSView.​

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Good luck,

Mark
http://www.peakhmi.com/

Sorry, I saw this post yesterday, but it was non-stop here all day, and didn't get a chance to respond.

Really, the handshake bit isn't all that useful 99.5% of the time. It is basically a digital tag you can configure that gets set to a 1 (True), when the associated alarm condition is active. If you leave auto-reset off, it will stay true until the alarm is acknowledged, and the condition is cleared. If auto-reset is on, it will just mimic the actual alarm condition (HS bit is TRUE when the alarm condition exists, and goes FALSE when it clears, whether acknowledged or not).

About the only practical use I've ever found for alarm handshaking on FTView, is a situation where you can have alarms coming from multiple devices. As a for instance, imagine you have a single FTView application monitoring run conditions from multiple PLC's. Using handshake bits would allow you to set up a single alarm beacon hanging off of one PLC, that would go active any time an alarm occurs (that is handshaked). It is a handy shortcut there as opposed to messaging back and forth between PLC's.

Note that by default, even if configured, handshaking is OFF. You need to explicitly turn it on with either a parameter to the AlarmOn command (/H), or the command HandshakeOn.

Much more useful is the alarm acknowledge bit, especially if you don't automatically clear alarm conditions in PLC logic. With that one, when the alarm is acknowledged on the HMI, the PLC is informed of the acknowledgment, and can automatically unlatch an alarm. Strangely, in this case, the handshake function can be useful as a feedback to the PLC to indicate that "Yep, I've cleared the condition".

Thanks for the great explanations. I set up a few alarms on a small panelview project I imported from a ME to SE. None of the alarms import. I did set up the acknowledge bit. The alarms seem to be working fine (thanks to the help of my friends on these messgage boards), but I wasn't sure If I needed to add the handshake bit. There will be 2 computers running the SE project, plus the original panelview. No multiple PLC's, but multiple HMI's.

Ach... importing alarms from a PV+ to SE is, well, simply not going to work. The alarming systems are completely different (of course).

You will have to actually create new alarms in SE.

Another reason for a handshake is when you are sending the alarms to multiple devices. The handshake makes sure the other devices saw the alarm. Also if you have multiple alarms it makes sure one alarm does not get overwrtten by another.

rdrast said:

Ach... importing alarms from a PV+ to SE is, well, simply not going to work. The alarming systems are completely different (of course).

You will have to actually create new alarms in SE.

Click to expand...

This the only reason to use handshake.