MVP 2021 Ausman Posted March 12, 2013 MVP 2021 Report Share Posted March 12, 2013 Hi all, A new forum member but have used small Unitronics gear on and off over the years. Question is a bit involved but please bear with me. I normally only work with standalone controllers, but I have a situation where I am going to be using two controllers and IOs that I already possess and may as well use…a V230 and a 120. I have an Ethernet card for the 230. Both PLCs are going to be using analogue IOs as well as digital. Having two controllers is best from a redundancy aspect in that the two main plant rooms will have a controller in each. The setup is controlling a small but complex pump, valve and power system. The issue I have is that I have to work around existing cable limitations tying in to the lack of Ethernet port for the 120. Both plcs have to be able to be accessed via remote. I have looked up programming examples a bit, but perhaps the easiest solution is if I pose my situation to the forum where hopefully someone can give me quick answers that won’t take too much of their time. The cable problem is that I only have 2 free cat5 runs between where the 2 controllers have to go. 1 end is near the router that will provide remote access. The other end is 80m away, which tests fine on Ethernet and also using the cat5 as 485. Owing to very full and awkwardly placed conduits, I simply cannot run any new cable between the endpoints, so Canbus on dedicated cabling is not possible although it would have saved me having to post this!! I only need to be transferring around 6 words of data b/n the two controllers in both directions, and speed isn’t essential. It is just so that some info can be seen and perhaps acted on at either end. So what will be the best layout? It’s a bit of a conundrum! I have the following ideas: 1). The 230 or 120 at either end, with the 230 on Ethernet and the 120 connecting by a serial to Ethernet/wifi adapter, but can communication between the two happen over this style of link? As in Ethernet talking to an essentially much slower serial conversion that is still ethernet? I could possibly use some spare pairs in the unused cat5 line to do digital signals b/n the two controllers to say a particular communication was happening/should happen etc. 2). The 120 at the far end, linked to the 230 by 485 with the 230 on Ethernet for remote access. However, my understanding is that I cannot remote access via Ethernet any controller linked by 485, although I can set up transfer of data b/n the two on 485. 3). Perhaps a variation of no. 1 where the controllers are linked by 485 for intercommunication, and I also have the serial to Ethernet adapter on the 120 to let me get into it remotely as well as the 230 by its native port. This one seems the most likely to me. 4). Somehow run canbus on the cat5, although everything I’ve read says this is not possible. 5). Put your suggestion here!! Trusting that you can see my puzzle! But don’t let me take too much of your time! This is not an urgent job and I will likely only check the forum/post once a day, so please don't be offended if I don't answer immediately. Cheers, Quote Link to comment Share on other sites More sharing options...
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