How many devices can be connected to SN3/DSN3?

Owned by ahsan Chaudary
Last updated: Dec 23, 2020
1 min read

When reading the below information please understand the following important points:

*The number of connected devices does not negate any of the standard OR requirements about sensor separation for detection or communication. The distance constraint for Infrared communication between sensor nodes is 3 meters.
*If a large number of devices (>5) is connected - then there will be a noticeable delay in the Sensor node boot time while the devices are addressed initially on bootup.

Devices on DALI bus in OR SN3/DSN3 is limited by;

  1. Max allowed 12 which can be any combination of drivers & emergency devices.
  2. The power available through power over DALI driver to be able to support 40mA (for sensor node) + 2mA (for each additional DALI driver)

Examples:

If using a PSU with 60 mA capacity, then spare mA available are:

  • (60-40) =20mA.
  • The maximum number of supported devices would be 10 (20mA/2 while assuming 2mA for each additional DALI device)

If using a PSU with 100 mA e.g., OSRAM 100 LI PSU then spare mA available are:

  • (100-40) = 60mA
  • In this case, even though we have DALI supply to support 30 devices in total in addition to sensor node, the total number of device would be limited to 12 as the maximum allowed limit.