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 converter, after 15 years replaced by converter RS232toMBus-XL45 from

Communication line configuration

  • Communication line category: Serial (both converters), 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
  • The station address is a decimal number within the range of 1..250 (or a hexadecimal number with a hash at the beginning, e.g. #0A) – it is a 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 the 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

KeywordFull nameMeaningUnitDefault value
Retry CountMaximum count of request retries. If no response returns after a request had been sent, the station's status will change to a communication error.-2
Retry TimeoutTimeout before resending a request if no response has been received.ms100 ms
Wait TimeoutThe delay between the response readings.ms500 ms
Wait First TimeoutThe delay after sending the request and before reading the response.ms800 ms
Max Wait RetryThe maximum number of retries of the response reading.-40
WakeUp LengthLength (given in characters) of a so-called wake-up message sent before each request.-20
WakeUp DelayThe delay between wake-up message and a request. It is recommended to enable the option WaitTxEMPTY in the line mode configuration.ms400

A string containing the protocol parameters is being defined as follows:

Keyword=value;Keyword=value; ...



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

I/O tag configuration

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

Address: A number from the following table must be entered (as a decimal number or as a hexadecimal number with a hash at the beginning, e.g. #0A):

Table 2

1Measuring device ID.Ci-
2Access number (measurement number incremented by 1 for each data reading).Ci-
3Status number, bit descriptions see the table 3, individual bits are sent to the value attributes.Ci-
4Heat quantity.AiMJ,GJ,kWh,MWh
5Heat rate.AiW,kW,MW
6Volume overflow.Ail,m3
7Volume flow.Ail/h,m3/h
8Forward temperature.AiºC
9Return temperature.AiºC
10Measuring device date+time.TiA-
11Heat quantity on the 1st date.AiMJ,GJ,kWh,MWh
12Heat quantity on the 2nd date.AiMJ,GJ,kWh,MWh
13Volume overflow on the 1st date.Ail,m3
14Volume overflow on the 2nd date.Ail,m3
151st date of data.TiA-
162nd date of data.TiA-

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

Meaning of status word bits (Ci address - 3)

Table 3

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