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WIRELESSMBUSEK

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20
Wireless M-Bus-EK
Rev. 0.1 7
8. PC Application
After installation, the Wireless M-Bus PC application is located in the following default directory:
C:\SiLabs\MCU\Wireless_Meter_Bus\Software\MBusDemo.exe
The initial screen is shown in Figure 6.
Figure 6. Wireless M-Bus Demo PC Application
If the M-Bus demo hardware is connected to the PC and the USBXpress driver has been installed, the demo board
serial number should be displayed in the Device drop-down menu. If the serial number is not displayed, perform
the following steps:
1. Check that the USBXpress driver has been installed.
2. Check that the shorting block configuration is set up according to the hardware setup.
3. Check the USB connection to your PC.
4. Check that the LCD displays are active.
If the LCD displays are not active, this indicates that the board is not powered.
Wireless M-Bus-EK
8 Rev. 0.1
The power consumption of the meter depends on the parameter settings. The PC application allows the following
parameters to be set:
Transmit Period
Data Field Length
M-Bus Mode
Transceiver Mode
Data Select
Pulse Frequency
Encryption
LCD Enabled
8.1. Transmit Period
The transmit period can be set for 1 second to 3600 seconds (5 minutes). The C8051F930 MCU will sleep for this
period with the Si4431 EZRadioPRO in shut-down. Then, it will wake up, take a measurement, and send the data.
The Transmit period has a large effect on the power consumption. A long transmit period is necessary to achieve
multi-year battery life.
8.2. Data Field Length
The data field length sets the length of the application payload in the M-Bus packet. The minimum length is 2,
including the required CI byte. The maximum is 100 bytes. If AES encryption is enabled, this field must be a
multiple of 16.
8.3. M-Bus Mode
The following menus can be used to select the M-Bus mode:
Mode S: 32,768 cps Manchester encoding
Mode SL: same as above with a very long preamble
Mode T: 100 kcps, three-out-of-six encoding
Mode R: 4800 cps, Manchester encoding
Mode T provides the highest data rate and gives the lowest power consumption. The current consumption of Mode
SL with the long preamble is slightly higher than Mode S. The long preamble is not necessary for the Si4431
EZRadioPRO. Power consumption is the highest using Mode R. Sending a long packet using Mode R may take
hundreds of milliseconds. Mode T2, Mode S2, and Mode R2 may be selected by choosing TX and RX in the
Transceiver mode menu. According to the specification, Mode R should always use TX and RX. For additional
information about M-Bus modes, refer to “AN451: Wireless M-Bus Software Implementation” and EN 13757-4.
8.4. Transceiver Mode
The Wireless M-Bus demo PC application provides two transceiver modes:
TX
TX and RX
If the TX only mode is selected, the meter will sleep for the transmit period, wake up, and transmit its data. If the TX
and RX mode is selected, the meter will wake up and send an access demand message. If the access demand
message is acknowledged, the meter will send its data to the other device.
When a meter reader (Other) device is present, the current consumption of the two-way communication is highest.
Because there is overhead associated with the two-way data transfer. If the meter reader (Other) is not present, the
two-way meter only needs to send the access demand message and wait for the response time. Still, the response
time is long compared to the message length; so, the one-way communication usually provides the lowest power
consumption.
Wireless M-Bus-EK
Rev. 0.1 9
8.5. Data Select
The options for the Data Select menu are:
Pulse
Temperature
None
The selected data is displayed on the LCD and transmitted in the data payload.
The Pulse option provides a pulse counter. The C8051F342 acts as a virtual water or gas meter. The C8051F930
will wake up on each rising and falling edge and count the number of pulses. The pulse rate is programmable.
The Temperature sensor uses the onboard temperature sensor on the C8051F930.
The power consumption will be higher using the pulse counter. This is because the MCU must wake up often to
count the number of pulses. Using the temperature sensor, the current consumption is less because the
temperature is only measured before each transmission.
8.6. Pulse Frequency
When pulse data is selected, the pulse frequency is programmable from 0.1 to 10 Hz. The 0.1 Hz provides one
pulse every ten seconds.
8.7. Encryption
The AES encryption option will encrypt the data before sending. The demo uses the AES 128 block cipher.
Ecrypting the data takes some extra time and results in higher power consumption. The encryption time will be
higher for longer data lengths.
Since the demo uses the basic AES128 block cypher, the data size must be a multiple of 16. The transmission data
should be padded with zeros. Other encryption modes might accommodate an arbitrary length.
8.8. LCD enabled
The LCD display takes power to operate and update. The three-pin header, J9, may be configured to exclude the
LCD current from the measurement. However, the C8051F930 is still updating the LCD display. Disabling the LCD
turns off the Meter display, and the MCU will not have to update the display. This decreases the time that the
C8051F930 has to be awake and lowers power consumption.
Normally, the CP2400 is powered from the same voltage supply as the C8051F930. However, the LCD current is
so low that the CP2400 may be powered from an I/O pin of the C8051F930. The LCD current may be further
decreased by configuring J13 with a shorting block on Pins 1 and 2. This powers the CP2400 from an C8051F930
I/O pin and further lowers the power consumption when the LCD is disabled.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P18P19-P20

WIRELESSMBUSEK

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Manufacturer:
Silicon Labs
Description:
Power Management IC Development Tools Wireless M-Bus Demonstration Kit
Lifecycle:
New from this manufacturer.
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