ben84

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About ben84

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  1. FX3U 0V interference

    Thank you, I understand. It is certainly food for thought. I will think of a way I can easily isolate each machine from each other. I am probably leaning towards the dry contacts/SSR's to provide that separation.
  2. FX3U 0V interference

    Thanks for the advice. Only the 0V from each machine is connected to one another on the terminal blocks before being connected to the PLC, the 24V signals are wired directly from each machine to separate inputs, so will never technically cross over.
  3. FX3U 0V interference

    Thanks for your reply. I see what you are saying, but I think in effect I have done what you are suggesting. The cabinet has a 0V rail and a 24V rail, and I've taken a wire from the 0V to the power input of the PLC, then taken a wire from this to the S/S terminal. So both the 0V and S/S are connected to the common 0V in the cabinet along with a 0V from each machine. I will double check they all lead to the common 0V, but thank you for answering that question. Now I know for sure they should all be connected to the same rail for referencing.
  4. FX3U 0V interference

    Good evening all, I have an issue with an FX3U PLC that is driving me up the wall, but have a feeling it's something that may seem daft to an experienced user. I would be extremely grateful for any help. Basically, I have one PLC taking 24VDC inputs from 3 separate machines but I'm experiencing interference with what I believe to be the 0V. I have wired a bank of 3 similar machines to another PLC without issue, but this one seems to keep presenting problems. When one machine is totally switched off, the PLC LED indicators of the inputs from it dimly flicker and then pop on in time with a machine that is still operational. Could someone please enlighten me how I should be wiring these up? Each machine is sending out its own 24VDC inputs to the PLC, which I have connected directly to the relevant inputs. I have a 24VDC power supply that I have connected to two banks of DIN rail terminals (24VDC and 0v) with a common bar on each bank to give me several connection points. From these terminals I have connected the PLC for its power source, plus taken a 0V from each machine and connected these to the same 0V DIN rail terminals. The S/S terminal on the PLC is connected to the 0V of the PLC. I'm certain this is where I've gone wrong (even though I have a carbon copy of this that works with the other 3 machines). Do I need to take 0V from each machine to use as a reference for the inputs? If so am I creating problems by having them joined to the same DIN terminal as the PSU I'm using for the PLC? Again, I realise I may be making myself sound silly but I am learning as I go along. Thanks for any help in advance