Configuration
Scanning
The ZHM-2x node scans for devices at Baud Rate 2400 starting at address 1 and proceeding to address 250. If
none are found, it tries all addresses again at Baud 9600 and finally Baud 300. The process restarts and
continues until a slave device is found.
Preset Settings
The ZHM-21 can be pre-configured through the Gateway if either the Baud or Address of the M-Bus device are
known. If one parameter is provided, the other will be scanned - so if a Baud Rate is provided, the 250 addresses
will be scanned at that baud rate only, or if the address is provided it will be scanned across baud rates 2400,
9600 and 300. When both are provided, no scanning is done.
Valid Baud Rates
When preconfiguring the settings on the ZHM-21, the following Baud Rates can be configured; 300, 600, 1200,
2400, 4800 and 9600. Of these, only 300, 2400 and 9600 are listed as recommended.
PARITY is always EVEN and STOP BITS are always 1 for M-Bus communication.
Connection
The connection to the M-Bus slave is done using a 2-core cable. T
he bus interfaces of the slaves are polarity
independent: that is, the two bus lines can be interchanged without affecting the operation of the slaves.
Besides protection aspects, this also results in simplified installation of the bus system.
Reading Data
The ZHM requests data from the Slave device using the M-Bus REQ_UD2 (Request for Class 2 Data). When the
RSP_UD (Data Transfer from Slave to Master after Request) has been received is it parsed by the ZHM which
then maps particular M-Bus “Value Information Fields” to EpiSensor Sensor IDs. It also converts from value
specific data types to EpiSensor data types.
The mapping is as follows;
M-Bus VIF
Description
Sensor ID Description
E000 0nnn
Energy, 10(nnn-3) Wh, 0.001Wh to 10000Wh
370
Energy (KWH)
E010 1nnn
Power, 10(nnn-3) W, 0.001W to 10000W
376
Power (W)
E011 1nnn
Volume Flow, 10(nnn-6) m
3
/h, 0.001l/h to
10000l/h
377
Volume Flow (Litres per Hour)
E101 10nn
Flow Temperature, 10(nn-3)
o
C, 0.001
o
C to 1
o
C
371
Heat Celsius Out (C)
E101 11nn
Return Temperature, 10(nn-3)
o
C, 0.001
o
C to 1
o
C 372
Heat Celsius In (C)
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