FactoryTalktotheHand
Member
Had an interesting phone call today with a fellow controls engineer who claimed that Continuous tasks are bad for the processor and cause it to "overload." What had happened was they were having issues getting online and their program consists of 5 tasks, all of which are Periodic, with update times ranging from 2ms to 1000ms. I added a Continuous Task with five rungs, do to some simple Counting. They're claiming it's my addition that is causing the trouble going online.
I was a bit taken aback by this for several reasons. I've never heard such a thing for one. Also, if Continuous tasks were universally bad for processors, why would Rockwell even allow you to program it that way? Third, isn't it the case that ALL A-B processors up until the Logix era ran EXCLUSIVELY as Continuous Tasks? Why would the Logix platform--a more powerful processor family--not be able to handle it when "lesser" processors could? Additionally, I've programmed quite a few Logix-family processors and have used almost exclusively Continuous Tasks. I've never had an issue with scan times or timing. Finally, how would this prevent one from going online with the processor? I've been online with this particular processor many times without issue. As a side note, their program was at least in part a conversion from a SLC program (they left all their tag names as N[7] and B[3] type tags), so I know for a fact that their program at one time DID run exclusively as a continuous task, on less powerful hardware with less memory.
Am I missing something here? Could my five rungs really have caused such a huge problem? I doubt it, and personally I think they were grasping at straws due to not being able to figure out the problem, but I'm willing to be enlightened.
I was a bit taken aback by this for several reasons. I've never heard such a thing for one. Also, if Continuous tasks were universally bad for processors, why would Rockwell even allow you to program it that way? Third, isn't it the case that ALL A-B processors up until the Logix era ran EXCLUSIVELY as Continuous Tasks? Why would the Logix platform--a more powerful processor family--not be able to handle it when "lesser" processors could? Additionally, I've programmed quite a few Logix-family processors and have used almost exclusively Continuous Tasks. I've never had an issue with scan times or timing. Finally, how would this prevent one from going online with the processor? I've been online with this particular processor many times without issue. As a side note, their program was at least in part a conversion from a SLC program (they left all their tag names as N[7] and B[3] type tags), so I know for a fact that their program at one time DID run exclusively as a continuous task, on less powerful hardware with less memory.
Am I missing something here? Could my five rungs really have caused such a huge problem? I doubt it, and personally I think they were grasping at straws due to not being able to figure out the problem, but I'm willing to be enlightened.