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larry818

FX3GE / modbus

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Hi, I have a couple of questions that seem to have stumped the MEAU guys... 1) Can I use the ethernet port on the FX3GE for modbus TCP? 2) If so, can I use it for modbus and programming simultaneously? 3) If not, can I add the FX3U-ENET (I know you can have only one enet card, I suspect the onboard one counts) 4) Did MEAU lift the port 502 restriction on the FX3GE? (Why did they disallow the standard port? Why do they sell a FX3U-ENET-P502 to fix this, and why only in the EU?) Ok, more than a couple of questions, and one compound question... Thanks! Larry

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1.) NO ONLY FX3U-ENET-P502

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To go into more depth: 1. No 2. If you use the ENET-P502, then yes you can do both 3. Yes you can, the onboard doesn't count 4. No, don't know why this idiotic decision, but it is what it is. I guess it is from older days, where ports below appr. 1000 are pre-defined ports handed out to various purposes, but why they haven't removed it now is pretty strange...
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Thanks Crossbow! I knew you'd know all the answers. So, when you say I have to use the -P502 to do both, I'm reading this to mean that I can't do both on the plain ENET module, even if I use another port?

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Funny, I just checked with the IANA list of ports, and port 502 is officially the "modbus tcp" port.

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I'm kaare_t but thanks! You need the P502 to use the 502 port. You can do Modbus on a different ports without problems, Modbus will work on any port, however the problem is the oposite device which most likely requires to use 502. If you use the ENET module you can use any higher port, on the ENET-P502 module you can in addition use port 502. IANA's list is correct as I stated below. I guess I explained myself a bit fuzzy - Low ports are still pre-defined for various purposes as you say by IANA. E.g. are web - port 80, DNS - port 23 and many more. Today, IANA also has a lot of higher ports pre-defined but I guess that this is something from the "Old days" of Mitsubishi where they decided that w.g. web ports could not be accessed in the module by custom protocols...

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