TP1 lines can be extended into TP1 areas. Maximum 15 TP1 lines can be combined into one TP1 area. The base for a TP1 area is its main line. A TP1 area main line is limited to one TP1 line segment, which shall NOT be extended by means of TP1/TP1 couplers. In order to connect a TP1 line to a TP1 area main line, a TP1/TP1 coupler is to be used. The TP1 area main line is to be connected to the primary side of this TP1/TP1 coupler. The TP1 lines that are connected to the secondary sides of the TP1/TP1 coupler are not limited to one TP1 line segment.
In order the calculate the area capacity for devices, the capacity taken by couplers and repeaters needs to be taken into account and the proportion of TP1-256 device and TP1-64 devices per segment and/or per line also needs to be taken into account.
Example: A TP1 area with only TP1-64 devices
Area capacity = [capacity main line] + [capacity line] x 15
- the capacity taken by the 15 TP1/TP1 couplers from the main line (primary side) is 15 x 1 = 15 devices
- per TP line:
- the capacity taken by the TP1/TP1 coupler for the connection with the main line (secondary side) is 1 device
- the capacity taken by the 3 TP1/TP1 couplers from the line (primary side + secondary side) is 3 x 2 = 6 devices
This brings the total capacity of an TP1 area to: [ 64 - 15 ] + [ (4 x 64) - 1 - 6 ] x 15 = 3784 devices.