Citect Alarms

Hi everybody,

I'm working on a project where i am trying to use local variables to activate alarms but i cant get it to work, so any help would be great.

i am using citect scada 2016 with the tab style HD template. i have created a local variable and added it to the advanced alarms and made a button that sets or resets that local variable.
i have tried both advanced alarms and digital alarms. In the expression field i have only put the local variable name in.

i cant work it out its driving me mad.

eddolls said:

Hi everybody,

I'm working on a project where i am trying to use local variables to activate alarms but i cant get it to work, so any help would be great.

i am using citect scada 2016 with the tab style HD template. i have created a local variable and added it to the advanced alarms and made a button that sets or resets that local variable.
i have tried both advanced alarms and digital alarms. In the expression field i have only put the local variable name in.

i cant work it out its driving me mad.

Click to expand...

Local variables don't work very well in some circumstances and this is one of them, they don't retain state or memory when the system is restarted.

Best way to do what you describe is to create a disk PLC device.

Thank you for your reply I will give that a go tomorrow. Do you know if local variables used to work in previous versions because we have a system that does use local variables but I believe it is citect 7.11. Also will using disc plc io increase my tag count?

eddolls said:

Thank you for your reply I will give that a go tomorrow. Do you know if local variables used to work in previous versions because we have a system that does use local variables but I believe it is citect 7.11. Also will using disc plc io increase my tag count?

Click to expand...

They have always worked the same, i am not sure why you are doing what you are doing anyway, seems a bit strange triggering and alarm from a push button, as i stated, if the machine is shut down the state will not be held.

Only Physical I/O will increase your point count.

Thank you for your advice, it all works brilliantly. The reason I was trying to use local variables was to reduce tag count by converting integers to 16 local variables. I have now done this by using the method you suggested. this has dramatically reduced my tag count.

Just tested on Citect2018, it appears that local variables will not trigger alarms, but disk tags will.

DrWarm said:

Just tested on Citect2018, it appears that local variables will not trigger alarms, but disk tags will.

Click to expand...

Yet another undocumented "feature" of 2018 that's bound to trip somebody up, we have found few little gotchas going to 2018 from older versions

Just to clarify how local variables work. Each runtime process has it's own copy of a local variable, so if the I/O server changes the value of the Local variable it will be for that process only. The alarm, report etc Local variable (same name)will maintain whatever value it has.

When eddolls mentioned it was working for a Citect version 7.1 i'm going to guess that it is running in single process mode and not multi process. That is about the only way it will work like that besides using ServerRPC() and MsgRPC() functions.