The MS/TP bus is subject to a number of physical factors that can affect performance. Consider the following common physical attributes:
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Check wires.
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Verify proper wire gauge, connections, polarity, and lengths.
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Look for opens and shorts.
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Check terminations.
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Verify that EOL terminations are only at the ends of daisy chains.
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Check addresses.
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Check for duplicate addresses.
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Verify that the address range is sequential.
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Check for and eliminate T-Taps (wire configurations that create a T shape) and star configurations.
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Check for consistent baud rates.
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Check for sources of interference.
Note: Use the Field
Inspection Tool (MS-FIT100-0) to test and troubleshoot the MS/TP bus that connects
supervisory controllers and field controllers to field point interfaces.