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Premex CALMEX II communication protocol

Supported device types and versions 
Communication line configuration
Communication station configuration
I/O tag configuration
Changes and modifications
Document revisions

Supported device types and versions

The protocol allows reading data from multifunctional calorimetric counters of the VKP and VKPs CALMEX II types by means of the M-Bus bus (originally used RS232/M-Bus Premex RS-M convertor, after 15 years replaced by converter RS232toMBus-XL45 from

Communication line configuration

  • Communication line category: Serial (both convertors), SerialOverUDP Device Redundant (RS232toMBus-XL45 only).
  • Mode 1: Baud rate 300, 8 bit, 1 stop bit, even parity, RTS=1, DTR=1 (RTS and DTR signals are not used by RS232toMBus-XL45).

Communication station configuration

  • Communication protocol: Premex CALMEX II
  • Station address is a decimal number within the range of 1..250 – it is VKP address. By default, the address is set by the manufacturer according to the serial number (identification number) of the measuring device as the last three digits. If last three digits are greater than 250, the higher digit of them is not taken into account. If the serial number is one of the numbers of 000, 300, 400, 500, 600, 700, 800, 900 then must be changed.
  • Recommended polling parameters: Delay at least 1 minute.

Station protocol parameters

The following station protocol parameters can be defined:

Table 1

Keyword Full name Meaning Unit Default value
RC Retry Count Poll repetition count in case of a communication error. - 2 seconds
RT Retry Timeout Delay between poll repetition in case of a communication error. ms 100 ms
WT Wait Timeout Delay between response readings till its finalization. ms 500 ms
WFT Wait First Timeout First waiting for response after sending the poll. ms 800 ms
MWR Max Wait Retry Repetition count of response readings till its finalization. - 40
WUL WakeUp Length Length (given in characters) of so-called wake-up message sent before each poll. - 20
WUD WakeUp Delay Delay between wake-up message and poll. It is recommended to enable the option WaitTxEMPTY in the line mode configuration. ms 400

String containing the protocol parameters is being defined as follows:

Keyword=value;Keyword=value; ...



If there is used a keyword with an invalid value in the initialization string, there will be used corresponding default value according the table 1.

I/O tag configuration

Possible I/O tag types: Ai, Ci, TiA

Address: It requires to enter one number, listed in the following table:

Table 2

Address Meaning Type Units
1 Measuring device ID. Ci -
2 Access number (measurement number incremented by 1 for each data reading). Ci -
3 Status number, bit descriptions see the table 3, individual bits are sent to the value attributes. Ci -
4 Heat quantity. Ai MJ,GJ,kWh,MWh
5 Heat rate. Ai W,kW,MW
6 Volume overflow. Ai l,m3
7 Volume flow. Ai l/h,m3/h
8 Forward temperature. Ai ºC
9 Return temperature. Ai ºC
10 Measuring device date+time. TiA -
11 Heat quantity on the 1st date. Ai MJ,GJ,kWh,MWh
12 Heat quantity on the 2nd date. Ai MJ,GJ,kWh,MWh
13 Volume overflow on the 1st date. Ai l,m3
14 Volume overflow on the 2nd date. Ai l,m3
15 1st date of data. TiA -
16 2nd date of data. TiA -

Values saved on 1st date or 2nd date are sent to the D2000 system with the save time. Measuring unit of individual parameters depends on the measuring device type.

Meaning of status word bits (Ci address - 3)

Table 3

Bit number Meaning Value attribute
0 Always 0. A
1 0 - current value, 1 - stored value. B
2 Low input power. C
3 Constant error. D
4 Temporary error. E
5 Water-meter error. F
6 Temperature pickups error. G
7 Always 0. H



Changes and modifications


Document revisions

  • Ver. 1.0 - March 13th 2001 – document creation.
  • Ver. 1.1 - 7. september 2016 – support for SerialOverUDP Device Redundant line, information about RS232toMBus-XL45 convertor.
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