Honeywell SmartVFD HVAC2 Applications Manual page 175

Modbus RTU
SmartVFD HVAC2 has a built-in Modbus RTU bus
interface. The signal level of the interface is in
accordance with the RS-485 standard.
The built-in Modbus connection of SmartVFD
HVAC2 supports the following function codes:
Table 56. Modbus RTU
Function Function
code name
03 Read
Holding
Registers
04 Read Input
Registers
06 Write Single
Registers
16 Write
multiple
registers
Broadcast
Address messages
All ID No
numbers
All ID No
numbers
All ID Yes
numbers
All ID Yes
numbers
Termination resistor
The RS-485 bus is terminated with termination
resistors of 120 ohms in both ends. SmartVFD
HVAC2 has a built-in termination resistor which is
switched off as a default (presented below). The
termination resistor can be switched on and off
with the right hand dip switch located above IO-
terminals in the front of the drive (see below).
AI2 GND DO- DI4 DI5 DI6 AO DO+
4 5 13 14
1 2 3
+10VAI1 GND 24V DI-C DI1 DI2 DI3
J500
Fig. 68. SmartVFD HVAC2 I/O
175
R13 R14
22
15 16 18 20
6 7 8 9 10
A
ON
OFF
* R24
23 26
25 24
B R21 R22
31-00108—07