fast alarms between plc and hmi

How can we make an hmi operator panel detect fast alarms? The scan cycle of the hmi is at least 100 ms, while the scan cycle of the plc is between 10 and 20 ms. So any alarm happening in less than 100 ms will not be detected by the hmi. We have thousands of alarm messages, many of them are fast…

If these alarms are so quick, then no one is going to be present to see them. So latch them in the PLC.

I agree with Saffa. For alarms, you are going to want to keep them active until an action is taken for them. A human being could not respond fast enough even with 100 ms to do anything about it if you don't latch them.

i did latch them, but how and when should i unlatch them? we are talking about hundreds of alarms, it is not practical that the operator does it one by one...

hi latch the alarm with itself...and a n/c contact of a reset button

maybe,

reset PB Blue (word) for normal alarm

reset PB Yellow (word) for fast alarm

Re-evaluate your alarms

If there are too many alarms for the operator to address then they really aren't doing any good. An alarm is intended to communicate to the operator that something is wrong and it needs to be handled. It would seem to me that you need to re-evaluate what you consider alarms and categorize them differently.

There can be alerts or flags that just get recorded but not addressed by the operator. These should not be alarms.

You could use a 2-3 second off-delay timer that keeps the alarm/event bit active long enough to give the HMI enough time to register it. It works well to capture blips.

Kataeb,

maybe you can adapt what we did to your app.
we had a machine with several hundred possible faults.
slc 500 plc.
we created a fault bit file with 20 words.
we created fault logic that turned on each bit in these words.
we used a pv 550 terminal with a messaging display to show the faults.
a subroutine scanned each word and bit for the faults.
if the word was equal to zero, next word.
if the bits was equal to zero, next bit.
when the bit equals 1, display the message for a specified time using a timer.

the fault reset logic was a single pb to reset the words at the top of the fault logic. as faults were fixed, the fault logic was cleared and the reset pb reset the bits.

we implemented this on a dozen machines and it quickly became our standard way of detecting faults.

hope this helps,
james