Modbus Rtu Mode; Fault Function On Modbus - Siemens RDF302/VB Manual

Device address
Baud rate
Parity
Note
Fault information
Priority of alarms
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3.11 Modbus RTU mode

The RDF302, RDF302/VB and RDF302.B thermostats support communication
protocol (Modbus RTU mode) as per the Modbus specification (refer to:
http://www.modbus.org).
The device address range is from 1 to 247.
The device address can be changed via parameter P81. (factory setting = 1)
The available baud rates are 4800 bps, 9600 bps, 19200bps and 38400 bps.
The baud rate can be changed via parameter P68. (factory setting = 19200 bps)
The parity can be set to none (no parity), odd or even.
The parity can be changed via parameter P70. (factory setting = even)
Any change, e.g. device address, baud rate and parity, will become effective only
after turning the power supply off then on again.

3.11.1 Fault function on Modbus

If a fault occurs (e.g. digital fault input, dew point, etc.) then a fault will be displayed
on the thermostat and the fault information can be read via Modbus.
If more than one alarms occur at the same time, the alarm with the highest priority
will be available via Modbus while the thermostat will display all active alarms
alternatively.
The table below shows the error code and default alarm texts.
Priority Fault
- No fault
1 Condensation
2 External fault
input X1 1)
3 External fault
input X2 1)
4 Clean filter
reminder
1) RDF302.B does not have inputs X1 and X2.
Default alarm texts are stored in the thermostat's non-volatile memory and can be
adjusted using the Modbus commissioning tool.
RDF302 Basic documentation
Thermostat Fault information on Modbus
Display Default fault text
--- No fault
Condensation in the room
Fault input 1
AL1
Fault input 2
AL2
Dirty filter
FIL
CE1P3079en
2022-06-17