ABB SensyMaster FMT430 Operating Instructions Manual page 71

SensyMaster FMT430, FMT450 THERMAL MASS FLOWMETER | OI/FMT430/450-EN REV. B
Limits and rules when using ABB fieldbus accessories
Figure 64: Bus cable length depends on the transmission rate
Pro PROFIBUS Line
(Line = Starts at DP Master and goes to last DP/PA Slave)
• Approximately 4 to 8 DP segments through the repeater
(see repeater data sheets)
• Recommended DP transfer rate 500 to 1500 kBit/s
• The slowest DP node determines the transfer rate of the DP
line
• Number of PROFIBUS DP and PA nodes ≤ 126 (addresses
0 to 125)
Per PROFIBUS DP segment
• Number of DP nodes ≤ 32
(Node = Devices with / without PROFIBUS address)
• Bus termination required at the beginning and end of each
DP segment!
• Trunk cable length (L ) see diagram
T
(length dependent on transfer rate)
• Cable length of at least 1 m between two DP nodes at
≥ 1500 kBit/s!
• Spur cable length (L ), at ≤ 1500 kBit/s: LS ≤ 0.25 m,
S
at > 1500 kBit/s: LS = 0.00 m!
• At 1500 kBit/s and ABB DP cable type A:
– Sum of all spur cable lengths (L
length (L ) > 6.60 m,
T
total length = L + (Σ L
T
maximum 22 DP nodes
(= 6.60 m / (0.25 m + 0.05 m spare))
) ≤ 6.60 m, trunk cable
S
) ≤ 200 m,
S
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