Does the ISY994i execute programs 1 program at a time or can/does it execute multiple programs at the same time? The programs in question do not have waits or repeats and the conditions may turn true at the same time.

 

Thanks,

Tim

It does not execute Program 1 to completion before executing Program 2 if that answers the question.

 

Multiple Programs are logically executing at the same time although not physically simultaneously. The processor can execute only one physical instruction at a time.

So it sounds like if I have 2 programs both of which are doing math functions and are sharing 1 integer variable as a place holder the data may get corrupt if they both run at the same time, esp. if one starts before the other but the other finishes first. So I will need a placeholder for each program.

 

Thanks Lee,

Tim

That is exactly right. Programs that can execute concurrently should not be updating the same resource. It would require an Enqueue/Dequeue function to serialize access to the resource which does not exist in the ISY.

Thanks Lee,

Once again you saved the day!