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Step 4: If all of the previous steps have been satisfied, then examine the “LINK” light on
the Ethernet module. It should not be red. If it is, then first make sure that the Ethernet
cable is hooked up at both ends. Remember that you must use straight through
standard CAT5 cables when going between the blender and a hub or switch. If you are
trying to go directly from the blender to a PC without using a hub or switch, then you
need to use a Crossed Ethernet cable. At this point you more than likely have a cable
problem and should test this. To test purchase a standard CAT5 cable that already has
the ends connected and a standard hub or switch (this can be purchased from Best
Buy, Circuit City, CompUSA, or Radio Shack). At the blender, power up the hub and
connect the blender using the new cable to one of the middle ports on the hub (say port
3 on a 4-port hub). Examine the LINK light and if it is now clear, then the problem is
definitely in your original cabling. This same test can be performed on the PC and PC
cable. All PC Ethernet cards have a LINK light as well. Establish the LINK light on all
devices before proceeding.
Step 6: If you have LINK lights on all units (including the PC) and no fault link lights on
the PLCs, but you still cannot establish communications, then we need to check the
PC’s network properties. If this computer resides on your plant network and was set up
by your IT department, then you will need to involve them for further assistance with
your problem. Instruct your IT department that the blenders must have a fixed IP, but
the PC can have a dynamic IP. All subnet masks for the PC and the blenders need to
be 255.255.255.0. They might not have the startup script correct for your PC. If the
blenders and PC all reside on a separate network that has nothing to do with your
plants LAN then we need to check the PC’s network properties (see “Chapter1
Networking instructions for the Sterling SGB Blender” for step-by-step).