16
Figure 21 Spring terminal Modbus connector
After 10 seconds without receiving a valid Modbus request with the default parameters, the controller will try to detect
a Modbus request with the alternative parameters (see Table 15 to see which registers are responsible for alternative
communication parameters).
The default values of the parameters responsible for the communication between the controller and AHU are
unchangeable - only the alternative parameters are to be changed.
Note - the settings of the device delivered with the VTS AHU are prepared by the manufacturer for optimal operation
and should be changed only in justified cases.
Function code
Description
1
Read Coil Status
2
Read Input Status
3
Read Holding Registers
4
Read Input Registers
5
Force Single Coil
6
Preset Single Registers
8
Diagnostics. Sub-function 00 Only – Return Query Data (loop back)
15
Force Multiple Coils
16
Preset Multiple Registers
Table 11 Available functions
