PLC Programming Riddle. How does the ONS work?
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- čas přidán 19. 11. 2023
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Regarding the second example (blind /see), I have seen code on quite a few old machines that use this style instead of a ONS.
Was this at one point the standard way? Or was that just a programming choice made by that particular person.
I'm not sure, the older I get, the more I appreciate the 2nd method because it is universal across brands.
Damn i was close! I called out the ons but not for right reason
There will be more...I'm not sure if there will be this Friday with Thanksgiving.
The one shot is a TTL trigger. Like on a D flip flop. Maybe JK flop
Would it help to show the IL or mnemonics to help people understand there is an actual step of low level instructions, vs. actual "power flow" emulation of an actual relay circuit. This is one of the reasons I like to use SET and RESET coils vs. latching input logic like you have (but I understand the latch input pattern, but as you described, behavior is not obvious). The one thing I do like about the input logic based latches is that you also program the "reset" logic in the same rung. This latch/reset rung pattern has been around for decades, but it still requires explanation of the "input contact" behavior of the "latching coil". The SET and RESET coil pattern typically is across multiple rungs (with "reverse logic" on the RESET rung - good application of DeMorgan's Law!)
What does "IL" stand for? I struggle with the acronyms 😁
@@TimWilborne Instruction List I think is what they are referring to, I believe.
@@TimWilborneSorry I did not respond sooner. One of the languages in IEC-61131 used to be Instruction List (aka IL), basically mnemonics. The standard has dropped IL since it was more tightly coupled to the implementation of the other languages, hence not really great for a "standard" (e.g. all microprocessors/vendors had to have the same assembly mnemonic instructions). Hence IL was dropped.
Rung 0 doesn't do anything since I (XIC) switch's it on or off with no other conditions. Not a good example of a one shot. Sorry.
Rung 0 certainly does something, in fact it works exactly the same as rung 1. Doesn't sound like you watched the full video.