Dan Blake

There is more than one solution that provides remote network access independent of the public-facing IP address given by your ISP. The product I use is an eWON Flexy. In two weeks I will be in Texas to install Flexies at two remote sites.

Hi Joe, Nice post. While generally avoided, I have used a sequence of (reset) coils connected in series. Usually the situation is when I need to clear previous operating states on power up. I will enable the rung with the first-scan contact. And you are correct, I do not like it when the logic is so complex that the rung has to fold back on itself. Often the logic can be rewritten using a couple of rungs, but sometimes it cannot be avoided. I am sorry if the comment you quoted came across as unduly harsh. I didn't mean it to apply specifically to Unitronics. In my current project I have replaced a 15" PV with a UniStream because I liked what I saw: cost, capabilities, and customer support. I was responding to another poster's post that because he didn't have intimate knowledge of how the ladder logic compiler worked, he couldn't trust how a given design would function. As programmers, it is not our job to understand the internal workings of a compiler. It is the job of the compiler designer to faithfully translate a ladder logic design into executable code. Cheers.

==> dB: Ask around and you will find that there are multiple ways of coding a valid solution. You will also run into designers who express the opinion that to not do it their way constitutes at least poor if not "extremely poor" programming . The more extreme the response, the more questionable the advice. => Ausman: Aren't you doing just that? No, I am not. I said that there are multiple valid solutions to a problem. At this point I made no comment about anyone's specific code. ==> dB: Your rung 9 example above will work just fine but looks wonky. I blame that on the software. A rung should have only a single connection to the left-hand rail, and the software should not allow more that. For that matter, it should allow only a single connection to the right-hand rail. I said C_R_PLC's code is a valid, if unorthodox, solution. I expressed my opinion that his style is not good practice and indeed should not be allowed by the software. I agreed with Flex727's solution to rewrite the rung using a single connection point with the LH rail. ==> dB: Regarding the need for SB 1 on rung 26 in Flex727's example above, I would say that is is unnecessary. If it turns out that without it the resulting logic does not perform as intended, that is a serious flaw in the software suite and if not addressed by Unitronics would cause me to look elsewhere for my PLC solutions. I am confident that that is not necessary. => Ausman: So on one hand you are saying there should only be a single connection to the LH rail allowed by the software, yet when Flex does this the most practical way you complain about it???? And you also say rung 9 will work just fine, going against your advice? Flex sugggested separating the rungs out but also offered alternatives. => Ausman: Discussion is welcomed on the forum, but nitpicking using conflicting statements within a post is not very helpful to anyone. Your welcome is appreciated, but realize that meaningful discussion necessarily involves diverse opinions. I wasn't nitpicking anything. I said contact SB 1 was unnecessary; I did not say it was wrong. This is called discussion. I suggested a different, IMO better, way to code rung 9. How is it going against my advice to acknowledge that the original method would work? I am not afraid to say that someone else's style would work. Yes, Flex offered an alternative solution., and I commented on it. More discussion. As explained above, there is no conflict in my original post. By the way, I checked with seven different PLC programming suites I have used in the past, Unitronics being the latest one. Three of them would allow a rung to make multiple connections to the left or right rail. Four of them would allow only a single contact point. I guess you know my preference. ?

Ask around and you will find that there are multiple ways of coding a valid solution. You will also run into designers who express the opinion that to not do it their way constitutes at least poor if not "extremely poor" programming . The more extreme the response, the more questionable the advice. Your rung 9 example above will work just fine but looks wonky. I blame that on the software. A rung should have only a single connection to the left-hand rail, and the software should not allow more that. For that matter, it should allow only a single connection to the right-hand rail. Regarding the need for SB 1 on rung 26 in Flex727's example above, I would say that is is unnecessary. If it turns out that without it the resulting logic does not perform as intended, that is a serious flaw in the software suite and if not addressed by Unitronics would cause me to look elsewhere for my PLC solutions. I am confident that that is not necessary.