How I can calculate the power supply needs to KNS system? Also how I can added more than power supply to one KNX bus?
Each KNX device working over KNX bus, has its current consumption written on installation manual (as you can see on attached picture).
We do provide three versions (current size) of power supplies. 160, 320 and 640mA.
For example to the 640mA KNX power supply can be connected up to 64 devices with a maximum capacity of 200mW and almost identical distribution on the line. In case of devices with different value of current consumption, it has to be counted to the power supply limit (in this case 640mA)..
If the current consumption of used group of devices in the project is higher, I do recommend to use a Line Coupler, where additional power supply is placed to the divided line. Please find in attached file more details regarding KNX Line Coupler ref. MTN680204.