Bms Communication - Lennox BAC020SNM Installation, Operating And Maintenance

CLIMATIC 50 – ROOFTOP – VERSION 23
Warning:
The power 24Vac of boards BM50 should not be connected to the earth

BMS Communication

The communication bus is connected to Climatic™ Serial Card daughter board on the BM50.
A star connection is not recommended, for an optimum operation it is advised to connect a maximum of two cables per unit.
In case of RS485bus, a resistance of 120Ω 1/4W can be connected on the last unit between the terminals + and -.
Connection must be carried out by the following cable:

Cable length up to 300m: AWG22 (0.34 mm ²), 2 pairs crossed with screen.

Cable length up to 1000m: LiYCY-P (0.34 mm ²), 2 pairs with general shield.
The cable length should not exceed 1000m.
For a better electromagnetic protection, Lennox recommends the use of LiYCY-P cable
BALTIC R410A-IOM-0708-E Page 97