Generally, the device has three separate interfaces:
- M-bus master interface for up to 64 or 128 devices
- ModBus RTU (RS-485) interface for connecting to PLC, PC, etc.
- ModBus TCP (Ethernet 10/100) interface for connecting to PLC, PC, etc.
Since ModBus has wide usage and m-bus is a special protocol
mainly for heat- and water meters, this device aims to connect
heat-, water- and electricity meters in a building to the
main SCADA. Selected m-bus devices can be activated in MMCR
memory. Then, with programmed period, every m-bus device
is read and information for it is updated in dedicated ModBus
registers. This interval can be from 1 minute to 12 hours.
That normally gives speed to the whole system, because there is no delay for the Main PLC through
modbus RTU. Data is transffered immediately (not wasting time to 'read' mbus) and can be at full
speed of 115200 bps.
For every device there is 28 register blocks (24 up to version v2.10), in which are
saved all m-bus parameters:
- main counter value
- m-bus primary address
- m-bus secondary address
- medium measured
- unit and constant
- tariff information (for pulse counter with tariffs –
like MBSS-xx)
- additional inputs information
- manufacturer of m-bus device
- status, flags and additional info
All m-bus details are important and we keep them updated.
Devices in ModBus memory can be activated or deactivated.
For Heat meters there are some more parameters that are saved -
Volume, Power, Temperature Inlet and outlet, etc.
Automatic search and activate for m-bus is available. In
ModBus memory devices are activated consequentially up to
64/128 devices, but primary m-bus addresses may not be from
1 to 64 (128) – this does not matter. In which data record which
m-bus device stands can be read through special registers
(see ModBus map). Readout intervals are settable and some
other things, which are described further.
Gineers offer software for setting MMCR-64. This software
has two main TABs:
- setting main parameters
- reading m-bus, activating ModBus devices
Main parameters for setting are:
- read general status – number of activated devices, m-bus
details, version
- read activated addresses
- set important m-bus details – using 0x5B or 0x7B when
REQ_UD, stop m-bus for one hour, sort m-bus devices in
ModBus memory, use SND_NKE initialization when m-bus commands,
etc
- set readout/update time
- set timeout between two m-bus readings
- set date and time of MMCR
- set ModBus address of MMCR-64
- set ModBus serial port details – speed and parity
- set TCP parameters – DHCP on/off, IP, Gateway, Mask (if DHCP is Off)
- set m-bus serial port details – speed and parity
Software options for working with m-bus devices are:
- searching m-bus network by primary address
- searching m-bus network by secondary address
- changing primary address of a device
- changing medium of m-bus devices
- changing main value (if device supports m-bus standard command)
- activating particular device in ModBus memory
- de-activate particular device in ModBus memory
- de-activate ALL devices
- read all active devices from ModBus side
- set automatic SEARCH AND ACTIVATE option – easy and
quick way to set all with one click
Of course, all described can be accomplished with other
software using ModBus map of the device. But it is good
to have quick-start and to see capabilities of the device
before starting to write your own code.
More info about configuration software you can find here:
MMCR Configuration
software
МMCR-64 starts to operate immediately after connecting
the supply voltage to it. The algorithm of work is as follows:
Starting initialization mode (0.2-0.3 s)
For about 0.2-0.3 s the device is busy with initialization
of important parameters. During initialization the output
is forbidden and the output voltage is 0 V. Leds ‘on’ and
‘prot’ (protection) are active. the output becomes active,
the unit then measures current consumption of the connected
slaves. Led ‘prot’ is turned off, led ‘out’ (allowed output)
become active. If short circuit, the m-bus output is held
forbidden and after a few second a new check is done, while
led ‘prot’ becomes active, led ‘out’ is turned off.
Normal operation mode
From the m-bus side device continuously measures current
consumption of the connected m-bus slaves. If the consumed
current becomes higher than 140 mA, the led 'over' is turned
on. If the consumed current becomes higher than 150mA, the
m-bus output is forbidden and turned off.
From modbus side device waits for commands to perform -
read/write of input or holding registers. Two interfaces
are completely independent from each other. Device tracks
programmed readout time period and if period has elapsed
- full readout of entire m-bus network is made automatically.
Then corresponding modbus registers are updated with readed
data.