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kseafield

Ethernet comms

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Hi guys, hopefully someone here has a logical explanation for me on this one. We ran some Cat6 cable from a HMI (Proface) to a switch about 50 meters away, that was connected to a laptop (from the dumb switch) for remote viewing. On the HMI side we terminated the cable with a normal RJ45 plug connector which went into a dumb industrial switch in the control panel. On the laptop side we done the same going into another switch. After all this, I couldn't establish any comms from the laptop to the HMI and after a whole day messing around with this, which included cable testing using two different cable testers that showed good connection statuses.....Someone in the office suggested using RJ45 socket connectors and normal pre-made patch leads from there on both sides. I wasn't convinced that this would work but was willing to try anything and done it, after we changed the connections over the comms worked immediately without issues. I've been working in the automation industry for a while now but haven't seen something like this before, does anyone have a logical explaining for me???

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Many of us have terminated Industrial Ethernet cabling before, correctly and incorrectly. It sounds like a loop tester would have come in handy to verify proper terminations. I also use WireShark, a freeware Ethernet sniffer utility. Set your PC IP address, turn off your PC wireless ports, unplug your network except for your PC and the master PLC, then sniff away. If someone re-addressed a device and fat fingered their work, WireShark should be able to sniff out the new address. For the 50m length cable, was this run in metallic raceway or near 3-phase conductors? For the long 50m cable, what is the cable manufacturer number? Did you verify the manufacturer specifications for maximum length and proper installation guidelines to manage noise immunity?

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