D-Link DE-805TP - 10Mbps Ethernet Mini Hub User Manual download pdf (Page 33)

Modbus for Field Technicians

Page 33

Tip #2 – Connection Order

Always connect the ground reference conductor first if you are connecting a

device that is powered up or you are connecting your laptop an operating

network.

Always choose devices that have optical isolation - this almost always will

protect the RS485 transmitter / receivers.

Tip #3 – Shield

You can get away without the shield. The twisted pair used for Tx and Rx is

more effective at noise cancellation than the shield.

Tip #4 – Cable Location

Take care where you run your cables. It seems obvious not to wind your cable

around other cables or sources of electricity / magnetism. People are often

surprised to find that the worst source of induced noise are switching DC

loads. Another big culprit are Variable Frequency drives.

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D-Link DE-805TP - 10Mbps Ethernet Mini Hub User Manual Page 33