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12.5.3 Spur lines
The trunk line on the PA module can have up to 32 spur lines with the following lengths:
Table 10 - Spur lines
Number of
Length of the spur
spur lines
25 to 32
Max 1 meter
19 to 24
15 to 18
13 to 14
1 to 12
The PROFIBUS PA specification allows up to 3 devices on a spur. Please refer to paragraph 12.5.1 for an
explanation on how to connect the PA trunk to the PA module.
12.5.4 Current consumption calculations
The PA module provides a maximum of 500mA to the PA trunk. The total current consumption of all slaves on
this trunk cannot exceed 500mA. The PA module consumes 10mA. At least one FDE (Fault Disconnection
Electronics, stated in the manual of the PA device) should also be calculated . The calculation for the current
consumption is as follows:
I
= I
+ I
+ .. + I
+ I
SEG
B0
B1
BN
I
= Total current in a segment
SEG
I
= Basic current of devices
BN
I
= Current of the Fault Disconnection Electronics
FDE
See Fig. 88 for an example.
ComBricks User Manual v6.4.0 | January 18| © PROCENTEC
(Non-Ex)
30 meter
60 meter
90 meter
120 meter
FDE
133/219
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