Hi guys!
Have been reading Profibus PA network installation guide and cannot understand the following:
IEC organisation published in IEC 61158-2 maximum spur cable length by number of fieldbus devices connected to the segment:
Number of devices: Spur cable length:
1-12 120m
13-14 90m
15-18 60m
19-24 30m
25-32 1m
What is described as well by IEC is maximum current consumed by all devices (hence max devices limit) and minimum voltage available for them (after cable voltage drop) - hence maximum spur length.
Everything if fine, but what sort of calculations must have been done to create above table? Why for 24 nodes one can have 24 devices, but when wants too add only one extra device the max spur length is limited 1m?
Am I missing some important factors that link voltage drop with current capacity?
Have been reading Profibus PA network installation guide and cannot understand the following:
IEC organisation published in IEC 61158-2 maximum spur cable length by number of fieldbus devices connected to the segment:
Number of devices: Spur cable length:
1-12 120m
13-14 90m
15-18 60m
19-24 30m
25-32 1m
What is described as well by IEC is maximum current consumed by all devices (hence max devices limit) and minimum voltage available for them (after cable voltage drop) - hence maximum spur length.
Everything if fine, but what sort of calculations must have been done to create above table? Why for 24 nodes one can have 24 devices, but when wants too add only one extra device the max spur length is limited 1m?
Am I missing some important factors that link voltage drop with current capacity?