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dcalderonv

CLX Processor speed

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Hello, I know scan times depend on task type and logic insida each one of them. Neverthless, I'd like to know what processor working frequency is for ControlLogix CPUs so I can compare them between different manufacturers. Doesn anyone have that information? Thanks in advance.

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My laptop has a dual-core 2.20 GHz processor... so why does it wait two seconds to show me a new Explorer window ? I agree that CPU clock rate is not an accurate comparison of controller speed or capability. The old 1756-L1 controllers ran a 20 MHz clock, while the current family of 1756-L6x controllers runs at 80 MHz. I expect the 1756-L7x controllers to be faster as well.

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Thanks Eddie that works for me. Do you have more detailed information on the processors themselves? Calderón

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No, I don't. The chips that run ControlLogix are custom silicon built by Rockwell. You can't compare them to a Pentium or an Atom.

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You can find if you dig thru the RA site manuals with the execution times for each instruction on each processor. Really Technical stuff if you need to figure stuff like that for some "Rocket Science project" or something.

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I beg to differ slightly. On the PLC-5 and SLC, this is very true and they are very predictable. However on a CLX platform, they seem to be worst case estimates if you actually do some timing measurements. Plus I think the word out about the L7x series is that they are double or triple the original clock speed. As to implementation, my suspicion with CLX is that it is either compiled code, or a byte code/threaded interpreter with some of super instruction type mechanism. I have heard various AB guys refer to Logix 5000 as a compiler though so I'm reasonably sure it's the latter. Plus it is blatantly obvious that the underlying programming language is C because the language features in Logix 5000 are such blatant C constructs. UDF's are literally C "struct"s for instance. All the atomic data types are blatantly identical to C, or how C handles them. My only real beef is why aliases are not done as pointers so that they could be repointed to a new object on the fly. Instead, they are merely symbol table entries with no layer of indirection. Fast but limited in functionality.

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