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5.2.4 Modbus connection - Connection to a BMS
In the case of a connection to a BMS, the Modbus connection, present in standard, allows:
• KUBAIR
®
F400 ECOWATT
®
Single phase or 3-phase - Control of the VAV variable flow rate:
-
On / Off
-
Speed adjustment
-
reading of registers (state of the casing).
• KUBAIR
®
F400 ECOWATT
®
Single phase or 3-phase - Adjustment to CAV constant flow rate:
-
On / Off
-
adjustment of the flow rate set point,
-
reading of registers (state of the casing).
• KUBAIR
®
F400 ECOWATT
®
Single or 3-phase - Adjustment to COP constant pressure:
-
On / Off
-
adjustment of the pressure set point,
• reading of registers (state of the casing).
Recommendation for ModBus connection.
The protocol used is ModBus RTU 485. It is imperative to respect the rules of the art of a ModBus
network for reliable communication.
You can connect up to 32 controllers on the same segment.
We recommend using twisted shielded cable with the following features :
• Max speed : 10 Mbps,
• Max : 6 dB,
•
Impedance : 120Ω (at 100 kHz),
• Capacity between conductors : 52.2 pF/m,
• Section 24 AWG / 0.22 mm².
The maximum recommended length is 1000 m for a segment for a speed of 19200 baud.
Derivations must be at most 40 m. The ModBus communication cable must be separated from the power
cable.
The shielding of the cable must be positioned in the wire rope clamp present in the controllers.
Terminations are required at each end of segment (120Ω + 1 nF).
Cabling example:
Convertisseur USB - RS485
RX / TX +
RX / TX -
Compacto 1
Compacto 2
Compacto 3
Terminaison 120Ω 1 nF
20 21 22 23
20 21 22 23
20 21 22 23
Segment
Dérivation
A1
B1
A2
B2
A1
B1
A2
B2
A1
B1
A2
B2
