Basic Documentation

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Siemens VAV Compact Controller Modbus RTU A6V10631862_en--_e
Smart Infrastructure 2021-10-26
With AST20, all parameters can be set using the mass configuration function. The
bus parameters are included in the mass programming routine. It can be selected
that the address is automatically incremented with each programmed VAV
controller. ACS941 supports saving and loading of parameter sets.
Figure 2: Bus configuration with AST20 (left) and with ACS941 (right)
6.3.3 Workflow 2: Full or partial configuration over bus
The devices can be configured over bus if the pre-commissioning settings allow for
a connection between the Modbus master (or programming tool) and peripheral
devices (non-conflicting address and matching baudrate / transmission format).
• Full configuration over bus: If the address is unique per segment when
powered up, the device can be accessed by the Modbus master (or
programming tool) and the address and other parameters can then be set to
the definitive values.
• Partial configuration over bus: If the address is not unique per segment when
powered up, each device must get a non-conflicting address before connecting
it to the bus (e.g. using the push-button addressing method). After addressing
all devices, the remaining configuration can be done over the bus using the
default settings for baudrate (or auto-baud) and transmission mode for the
Modbus master.
• Overwriting the bus configuration over bus uses a timeout. If “1 = Load” is not
written into Register 768 within 30 seconds, all values are discarded.
The following table shows bus configuration registers before and after changing
them over bus. Attention is to be paid to register 768.
Reg.
Name
Pre-commissioning
New value (ex.)
764
Address
46
12
765
Baudrate
0 = auto
1 = 9600
766
Transmission Mode
0 = 1-8-E-1
3 = 1-8-N-2
767
Termination
0 = Off
0 = Off
768
BusConfigCmd
0 = Ready
1 = Load
Note
ENTER ↓
Example